Shelford Tutorials

LINE BY LINE EXPLANATION OF NCERT, CLASS 7 - SCIENCE, CHAPTER 1: NUTRITION IN PLANTS

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Line by line explanation of OUR LIVING WORLD, Science book, CLASS 6: CHAPTER 2: FOOD: DAV GROUPS/SCHOOLS

2021-06-14T20:10:00.000+05:30

ORDER HEMIPTERA

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The hemiptera are a large frequently encountered order, members of which are extremely diverse in size shape and colour. They include insects commonly known as bugs, leafhoppers, cicadas, aphids, lerps and scale insects. The most distinctive feature of hemipterans is their sharply pointed, tube-like mouthparts (proboscis or rostrum) that are used for piercing or sucking. Hemipterans usually have two paier of wings, however some groups may be wingless and others have only forewings. They feed on juices of plants or animals.

The Order Hemiptera is divided into four Suborders

1. Heteroptera (true bugs)

The term heteroptera, derived from greek, hetero-different; ptera-wings; The forewings are hardened at the base, membranous at the tips, and sitting flat over abdomen, hiding the membranous hind wings; the head and proboscis can flex forward and some predatory species have raptorial forelegs.

Wings lie flat on the back at rest, forming an ‘X’

Figure 1: Heteroptera: Leptocorisa

2. Auchenorrhyncha (cicadas, spittlebugs, leafhoppers, planthoppers and tree hoppers)

They have forewings uniform in texture and held like a tent over the abdomen; the head and proboscis are directed down and back and many have hind legs adapted for jumping.

Figure 2: Auchenorrhyncha: Nilaparvata lugens

3. Sternorrhyncha (psyllids, whiteflies, aphids, mealy bugs)

They are usually small, soft bodied and generally wingless; the head and proboscis are directed down and back, and in some the legs are vestigial or absent. Many species cover themselves with wax to prevent their soft bodies from dessicating.

Figure 3: Sternorrhyncha: Cereal aphid

4. Coleorrhyncha (moss bugs)

They are small, rarely seen, group of flattened, mostly flightless bugs that are found amongst mosses and liverworts.

Blood Sucking Bugs (Order Hemiptera; Suborder Heteroptera)

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BLOOD SUCKING BUGS

FAMILY CIMICIDAE (BED BUGS)

The Cimicidae form a well-defined family of blood sucking bugs. They are oval flattened insects without functional wings, although the forewings remain present as two small pads on the dorsal surface of the thorax.

There are 91 recognized species of Cimicidae.

· Most are associated with birds and/or bats but two species Cimex lectularius and Cimex hemipterus are the familiar bedbugs commonly associated with man.

· Both species lay their eggs in cracks and crevices of houses and outbuildings.

· Each female bedbug lays about 200 eggs, which hatch about after 10 days at 20 degree Celsius.

· The nymphs and adults usually feed at night when their hosts are sleeping, although they will feed during the day if conditions are favourable.

· Feeding behaviour, and hence development, is critically dependent on temperature and humidity.

· Bedbugs do not feed at temperatures less than 13 degree Celsius.

· Experimental evidences show that bedbugs can be infected with a range of human parasites and pathogens, including hepatitis-B, HIV and Trypanosoma cruzi.

· Bedbugs will feed daily if given the opportunity and their high numbers can contribute to chronic iron-deficiency anaemia, especially in infants.

FAMILY POLYCTENIDAE (BAT BUGS)

The family polyctenidae comprises 32 species grouped in five genera. They are small ectoparasites of bats, with no known medical importance. They lack eyes and ocelli and are always flightless with forewings reduced to small flaps. The bugs are parthenogenetic. Bat bug Hesperoctenes.

FAMILY REDUVIIDAE & AND SUBFAMILY TRIATOMINAE (KISSING BUGS)

Most reduviidae are predators on insects and other invertebrates. They are predominantly tropical, occupying a very wide range of terrestrial habitats and displaying a variety of hunting strategies and pre preferences. Over 6000 species are known, which are grouped into 23 subfamilies. In many predatory reduviids, the fore legs are adapted to hold prey. Often the fore legs (sometimes mid legs) are strongly raptorial, equipped with spines, adhesive organs and/or glands secreting a glue-like substance.

Subfamily Triatominae (Kissing bugs)

There are 118 species of Triatominae recognized on the basis of morphological characters. They range from 5mm to 45 mm in length.

All species of triatominae are obligate bloodsuckers and over half have been shown naturally or experimentally to be susceptible to infection with Trypanosoma cruzi.

Epidemiologically only about a dozen species have become sufficiently closely associated with man to represent a public health problem; of these the most important vector species are Triatoma infestans, Panstrongylus megistus, Rhodnius prolixus, Triatoma brasiliensis and Triatoma dimidiata.

Other species are mainly associated with nest-building birds and small mammals, and occasionally reptiles.

References

· Medical Insects and Arachnids Edited by Richard P. Lane and Roger W. Crosskey. Published in 1993 by Chapman & Hall ISBN 0 412 400006

DIGESTIVE SYSTEM: INTRODUCTION AND GENERAL PLAN OF ALIMENTARY CANAL

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UNIT 1 – DIGESTION AND ABSORPTION OF FOOD

SL – STRUCTURE AND FUNCTION OF DIGESTIVE GLANDS[i]

NERVOUS SYSTEM

The nervous system is divided into

1. Central nervous system (CNS)

2. Peripheral nervous system (PNS)

2.1. Somatic nervous system (SoNS)

2.2. Autonomic nervous system (ANS)

2.2.1. Sympathetic nervous system (SNS)

2.2.2. Parasympathetic nervous system (PsNS)

1. Central nervous system (CNS) - it comprises of the brain and spinal cord – also called as the body’s master control unit

2. Peripheral nervous system (PNS) – it includes all the nerves arising out and going to the central nervous system – also called the body’s link to the outside world

2.1. Somatic nervous system (SoNS): cerebrospinal- it is a part of the peripheral nervous system, is associated with the voluntary control of body movements via skeletal muscles. The somatic nervous system consists of (afferent nerves) sensory nerves and (efferent nerves) motor nerves. The somatic nervous system controls all voluntary muscular systems within the body, and the process of voluntary (somatic) reflex arcs.[1]

2.2. Autonomic nervous system (ANS): visceral

2.2.1. Sympathetic nervous system (SNS) – the action of most of the organs is accelerated by the SNS

2.2.2. Parasympathetic nervous system (PsNS) – the activity of most of the organs are inhibited by PsNS

It must by however noted that, all the nervous activities are always controlled by the central nervous system; the peripheral nervous system are merely carriers of the information.

Only a small part of the body activities are under the willful (coluntary) control of the body. The centers for the control of voluntary activities are present in the thalamus and cerebral cortex of the brain. These are therefore called as the conscious areas of the brain. Most of the organs of the body are controlled by an automatic feedback circuit in which no conscious thinking is required. Such activities are termed as involuntary and are controlled by autonomic nervous system. The centers for involuntary actions are present in the medulla oblongata, pons and midbrain.

The SNS regulates actions that require quick action and PsNS calms down the actions of SNS.

The PsNS regulates the actions that do not require quick responsiveness.

1. Motor functions

2. Sensory functions

DIGESTIVE SYSTEM

Digestion is the mechanical and chemical breakdown of foods into forms that the cell membranes can absorb.

Mechanical digestion breaks large pieces into smaller ones without altering their chemical composition

Chemical digestion breaks food into simpler chemicals.

The digestive system carries out ingestion, propulsion, digestion, absorption and defecation.

The digestive system consists of the alimentary canal, extending from the mouth to the anus, and several accessory organs, which release secretions into the canal.

The alimentary canals includes the mouth, pharynx, oesophagus, stomach, small intestine, large intestine, and anal canal.

The accessory organs include the salivary glands, liver, gall bladder and pancreas.

The digestive system originates from the inner layer (endoderm) of the embryo, which folds to form the tube of the alimentary canal. The accessory organs develop as the buds from the tube.

DIGESTIVE SYSTEM

The digestive system consists of the alimentary canal, extending from the mouth to the anus, and several accessory organs, which release secretions into the canal. The alimentary canal includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine and anal canal. The accessory organs include the salivary glands, liver, gall bladder and pancreas. The digestive system originates from the inner layer (endoderm) of embryo, which folds to form tube of alimentary canal. The accessory organs develop as buds from the tube.

The mouth is followed by a muscular tube (Pharynx). The pharynx leads to a spacious chamber – stomach, through a narrow tube – oesophagus. The passage from the oesophagus to the stomach is guarded by a valve known as cardiac spinchter. The stomach is followed by small intestine which can be divided into three parts – duodenum, jejunum, ileum.

The distal end of the stomach opens through pyloric spinchter into the duodenum. The middle part is jejunum and the last part is ileum.

The small intestine (ileum) opens into the large intestine (colon) through ileo-colic valve.

A vermiform appendix is present at the site of ileo-colic valve which is vestigial in human beings.

The colon leads into the last part of intestine – rectum. The rectum opens outside the body, the rectal opening is guarded by anal spinchter.

[2]

[3]

[4]

[5]

GENERAL PLAN OF THE ALIMENTARY CANAL

The alimentary canal is a muscular tube about 8 meters long that passess through the thoracic and abdominopelvic cavities. The structure of its walls, function and innervations are similar throughout its length with slight modifications at places.

Structure of the wall

The wall of alimentary canal consists of four distinct layers that are developed to different degrees from region to region. The four distinct layers persists throughout the alimentary canal, but certain regions are specialized for particular functions. Beginning with innermost tissues, the layers are as follows.

1. Mucosa layer

This layer is formed of surface epithelium, underlying connective tissue (lamina propria), and a small amount of smooth muscles (muscularis mucosa). In some regions the mucosa is folded with tiny projections towards lumen. This increases the absorptive surface area.

The mucosa has tubular invaginations, which are lined by cells that secrete mucus and digestive enzymes.

2. Submucosa layer

Next to the mucosa layer is the submucosa layer. It contains considerable loose connective tissue as well as glands, blood vessels, lymphatic vessels, and nerves. Its blood vessels nourish the surrounding tissues and carry away absorbed materials.

3. Muscular layer

This layer, which provides movement of the tube, consists of two layers of smooth muscle tissues. The outer is the layer of longitudinal muscle. The inner is the layer of circular muscle. The contraction of circular muscle fibers reduces the diameter of lumen of the alimentary canal; the contraction of longitudinal muscle layers shortens the length of the tube.

4. Serosa

The serosa layer is the outer covering of the tube; it is composed of the visceral peritoneum, which is formed of epithelium on the outside and connective tissue beneath. The cells of serosa protect the underlying tissue and secrete serous fluid, which moistens and lubricates the tubes outer surface so that the organs (which are lined by parietal peritoneum) slide freely inside the body cavity and against one another.

5. Gut associated lymphoid tissues (GALT) – Peyer’s patches

Innervation [6]of the tube

Branches of the sympathetic and parasympathetic divisions of autonomic nervous system extensively innervates the alimentary canal. These nerve fibers, mainly associated with tube’s muscular layer, maintain muscle and regulate the strength, rate and velocity of muscular contractions.

Many of the postganglionic fibers are organized into a nerve plexus [7]within the wall of the canal.

The submucosal (Meissner’s plexus) plexus is important in controlling secretions of gastrointestinal tract.

The myenteric plexus of the muscular layer controls the gastrointestinal motility

The nerve plexus of the gastrointestinal tract are so extensive, that it is some times said to have a ‘second brain’.

** a great advance in our knowledge of gastric digestion, particularly in man, was made through the observations of Beaumont on his patient, Alexis St. Martin who in 1822, following a gunshot wound was left with an opening from the stomach through the abdominal wall to the exterior. Through this fistula, Beaumont found it possible to follow the course of gastric digestion of different food under varying conditions of health and obtained pure gastric juice for digestion experiments outside body

Movements of the tube

The motor functions of the alimentary canal are of two basic types – mixing movements and propelling movements

Mixing occurs when smooth muscles in particular segments of tube contract and relax rhythmically. For example – when the stomach is full, waves of the muscular contractions move along its wall from one end to the other. These waves occur every twenty seconds of so. They mix the digestive juices secreted by the mucosa with food.

Propelling movements include a wavelike motion called – peristalsis. During peristalsis a ring of contraction appears in the wall of the tube. At the same time the the muscular wall just ahead of the ring relaxes – a phenomena called as receptive relaxation.

Law of gut: when a segment of the intestinal tract is excited by distention and thereby initiates peristalsis (peristaltic reflex), the contractile ring causing the peristalsis normally begins on the orad [8]side of the distended segment and moves towards the distended segment, pushing the intestinal contents in the anal direction for 5 – 10 centimeters before dying out. At the same time the gut relaxes several centimeters downstream toward the anus (receptive relaxation), thus allowing the food to be propelled easily towards the anus.

This complex movement occurs only in the presence of the myenteric plexus. Therefore the movement is called the myenteric reflex or peristaltic reflex.

The peristaltic reflex and the movement of peristalsis towards anus is called the “law of gut”

[1] There are two types of reflex arcs; the autonomic reflex arc – affecting inner organs and the somatic (voluntary) reflex arc – affecting skeletal muscles.

[2] https://www.newhealthguide.org/Pyloric-Sphincter-Function.html

[3] https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcR09b3hIlAQsXZmPGhKUKzlHCgt4sKEX3DSz8Fe0bL6bs6P6IUB

[4] https://thumbs.dreamstime.com/z/gallbladder-duct-anatomy-pancreas-liver-duodenum-s-stomach-detailed-description-86699426.jpg

[5] https://i.pinimg.com/originals/b8/b7/39/b8b739c5b9e4618fe9bbb7ec7e0013e8.jpg

[6] Supply nerves to; to put the nerves into

[7] network

[8] Towards the mouth; oral direction

[i] Guyton, Hall, Textbook of Medical Physiology, 11^th Edition, Elsevier

Shier D, Butler J, Lewis R – Hole’s Human anatomy and Physiology, 11^th Edition

Agarwal, Srivastava, Kumar – Animal Physiology and Biochemistry, 5^th Edition, 2013, S. Chand & Company Ltd

Verma, Tyagi, Agarwal – Animal Physiology, 2015, S. Chand & Company Ltd

Asim Kumar Datta – Functional Histology, 1^st Edition, Current Books International

ORIGIN & EVOLUTION OF REPTILES

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ORIGIN & EVOLUTION OF REPTILES

Reptiles evolved from amphibians of Carboniferous period[1], which depended on water bodies for laying eggs and development of larval stages and hence could not exploit arid/terristrial habitats far away from water bodies.

They developed a large yolk-laden [2]shelled egg that could be laid on land and in which an amniotic[3] sac contained fluid in which embryo could develop to an advanced stage, capable of fending for itself when hatched. The following anatomical changes transformed the ancestral amphibians into land adapted reptiles:

Body developed a covering of epidermal scales to prevent loss of body moisture, and skin became cornified and devoid of glands.
Skull became monocondylic[4] for better movement and flexibility. Atlas and axis vertebrae together permitted skull movement in all directions.
Limb bones and girdles became stronger but limbs were attached on the sides of body, and belly touched the ground during creeping mode of locomotion.
Sacral region involved two strong and fused vertebrae to support the body weight on hind legs.
Pentadactyle limbs developed claws that helped in climbing on rocks and trees.
Respiration through lungs became more efficient to use the oxygen available in the air.
As a water conservation strategy, metanephric kidneys excreted uric acid which did not require water for excretion.
Reptiles continued to be ectothermal since ventricle was not completely partitioned[5] by a septum and blood mixed in heart.
Internal fertilization evolved as a large cleioid[6] shelled egg was laid on land.
Embryonic membranes amnion, allantois and yolk sac evolved to enable embryonic development in arid conditions.

ANCESTORS OF REPTILES

1. THE ANAPSIDS (THE COTYLOSAURS)

They were the most primitive stem reptiles that evolved from the labyrithodont amphibians (Embolomeri) in Carboniferous period.

Seymoria was a lizard-like animal, with pentadactyle limbs and a short tail. It had homodont labyrinthine teeth on the jaw bones as well as on vomer and palatine bones. Presence of lateral line indicates its amphibious habits. Skull was monocondylic for better movement of head. Seymoria indicates gradual transition from labyrinthodont amphibians to reptiles. Another 5 foot long cotylosaur fossil, Limnoscelis was found in Mexico that had large premaxillary teeth and long tail.

2. THE PARAPSIDS

They possessed superior temporal vacuity in the skull and were adapted for aquatic mode of life.

Plesiosaurus was marine long-necked, fish-eating animal with 15 metre long fusiform body, short tail and paddle-like limbs modified for swimming. The skull was euryapsid type with a superior temporal vacuity. The fossils are from lower Jurassic (about 180 million years) and they are believed to have become extinct in end-Cretaceous mass extinction.

Ichthyosaurus had fish-like body with fore limbs modified into paddle-like fins and hind limbs disappeared. There was a fleshy dorsal fin too. Caudal fin was large and bilobed. Jaws projected into an elongated snout and teeth were homodont, an adaptation for fish-catching. Skull was parapsid type with additional postfrontal and supratemporal bones behind the eye orbit. Vertebral column became secondarily simplified with amphicoelous vertebrae.

3. THE SYNAPSIDS

Synapsids split off from the primitive reptilian stock very early in evolution, perhaps in the middle carboniferous period. Synapsids had started developing mammalian characteristics that enabled them to be fleet-footed and active predators. Their legs commenced to move under the body. Heterodont dentition and false palate started developing in pelycosaurs and had been completely formed in therapsids. Two types of synapsids occurred from carboniferous to Permian, namely, the primitive Pelycosaurs and advanced therapsids.

Pelycosaurs are represented by Dimetrodon whose fossils were discovered from North America and Russia from the late Carboniferous to Permian periods. They were primitive reptile-like animals in which limbs had moved under the body but not completely and each limb had 5 digits with claws. Neural spines on the back were excessively long stretching highly vascularized skin between them that formed a fin-like or sail-like structure. They had heterodont dentition with incisors, canines and molars clearly defined but the false palate had not been completely formed.

Therapsids were more advanced and active synapsids which were perhaps endothermic animals with high rate of metabolism. Heterodont dentition with false palate allowed these animals to chew and grind food for quick digestion in the gut so that high metabolic demand of the body could be fulfilled. Jaw muscles were attached to zygomatic arch to make chewing effective. Carnivore therapsids were called Cynodonts (ex. Cynognathus) and herbivores were Dicynodonts.

4. THE THECODONTS

They evolved from the sauropsid Archosauria, a group of insignificant lizard-like reptiles that survived the Triassic mass extinction. They evolved into bipedal and highly agile predators.

Euperkeria and Ornithosuchus fossils were unearthed from South Africa and Europe. They were about 2 ft long bipedal lizard-like animals with small head but very long tail for balancing while they chased flying insects by rapid running. Endothermy must have evolved in thecodonts to meet the extraordinary energy demands of their predatory life style.

5. THE SAURISCHIANS

They were dinosaurs with lizard-like pelvic girdle in which ischium and pubis bones radiated away from each other. They were both bipedal and quadrupedal and carnivores as well as herbivores.

6. THE ORNITHISCHIANS

They were dinosaurs with bird-like pelvic girdle in which ischium and pubis bones were directed towards posterior as found in modern birds. These were also highly diversified carnivores as well as herbivores and both bipedal and quadruped.

7. THE PTEROSAURIA

They were flying or gliding dinosaurs of Mesozoic that varied in size from sparrow-sized to some species, like Pteranodon, having a wing span of 8 meters. They had pneumatic bones. Last digit of the fore limb was extraordinarily long and served to attach the membranous patagium between fore limb, hind limb and the body. Hind limbs were used for clinging on to the rocks and cliffs and 3 digits of fore limbs also had curved claws, an adaptation for clinging. Their jaws were modified into beak that possessed homodont dentition but Pteranodon did not have teeth

[1] The carboniferous period is famous for its vast swamp forests. The swamps produced coal from which the term carboniferous is derived. It lasted from about 359.2 to 299 million years ago.

[2] The eggs of reptiles are macrolecithal, they contain large amount of yolk for development of embryo into miniature adults which can feed and defend themselves.

[3] The amniotic egg of reptiles and birds is surrounded by a tough outer shell that protects the egg from predators, pathogens, damage and from drying. Oxygen passes through tiny pores in the shell, so embryo doesn’t suffocate. Inside the shell are four sac. The first sac inside the shell is chorion, which carries oxygen from the shell to the embryo and waste carbon dioxide from the embryo to the shell. Within the chorion is amnion, the membrane for which the amniotic egg is named. The amnion keeps the embryo from drying out, so it’s critical to living on land. A third sac, the allantois, stores wastes from the embryo and also fuses with the chorion to form the chorioallantoic membrane, ehich carries oxygen and carbon dioxide to and from the embryo, just like lungs. A fourth membrane, the yolk sac, holds and digests nutritious yolk for the developing embryo.

[4] Monocondylic skull has one occipital condyle in skull, it provides high degree of movement.

[5] Two atria and one ventricle. The two atria and one partially divided ventricle. There is a mixing of oxygenated and de-oxygenated blood because the ventricle is not split completely.

[6] Birds lay hard-shelled eggs, but most reptiles lay soft-shelled eggs. Bird’s eggs are incubated by body heat, but reptile eggs are incubated by natural heat. The reptiles eggs are hidden, thus are all white. The birds eggs are incubated in nests and are exposed thus show colouring and camouflage. * amniotic egg

GENERAL INFO ON HAZARDS

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1. What is hazard?[i]

A hazard is an object, situation or behaviour that has the potential to cause harm in terms of injury, ill health or damage to property. Hazards can appear in many working circumstances. Some hazards pose an immediate danger, while others take a longer time to materialize.

Hazards can be classified as –

Physical hazard (temperature, ionizing/non ionizing radiation, excessive noise, electrical exposure etc.)

Mechanical hazard: created by machinery, moving parts etc.

Chemical hazards: exposure to chemicals in workplace or elsewhere.

Biological hazards: due to viruses, bacteria, fungus etc.

When we refer to hazards in relation to occupational safety and health the most commonly used definition is - a hazard is a potential source of harm of adverse health effect on a person or persons.

The term hazard and risk are often used interchangeably but there is great difference between hazard and risk

Example: if there is an open manhole, then the manhole would present a hazard where a person may fall and get hurt. If access to that area is prevented by a physical barricading then the risk of any one falling in manhole and getting hurt is minimised, but the open manhole – which is a hazard, is still there.

What is a risk?

The commonly used definition is - a risk is the likelihood that a person may be harmed or suffers adverse effects if exposed to a hazard.

2. What is environment?[ii]

Environment is everything that is around us. It can be living or non-living things. It includes physical, chemical and other natural forces. Living things live in their environment. They constantly interact with it and adapt themselves to conditions in their environment.

3. An environmental hazard is a substance, state or event which has the potential to threaten the surrounding and natural environment and/or adversely affect people’s health, including pollution and natural disasters such as storms and earthquakes.

ENVIRONMENTAL HAZARD EVENT[iii]

Environmental events become hazards once they threaten to affect society and/or the environment adversely. A physical even, such as volcanic eruption, that does not affect human beings is a natural phenomenon, but not a natural hazard. A natural phenomenon that occurs in a populated area is hazardous event. In areas where there are no human interests, natural phenomena do not constitute hazards nor do they result in disasters.

MULTIPLE HAZARDS

When more than one hazard event impacts the same area, there arise a multiple hazard situation. These different hazard events may occur at the same time or may be spaced out in time.

RETURN PERIOD

Majority of hazards have return periods on human time-scale. Examples are five year flood, fifty year flood and a hundred year flood. This reflects a statistical measure of how often a hazard event of a given magnitude and intensity will occur. The frequency is measured in terms of hazard’s recurrence interval.

For example, a recurrence interval of 100 years for a flood suggests that in any year, a flood of that magnitude has a 1% chance of occurring.

Such extreme events have very low frequencies but very high magnitude in terms of destructive capacity. This means that an event considered being a hundred year flood would cause severe damage compared to a five-year flood.

CLASSIFICATION OF HAZARDS

There are many different ways of classifying hazards. One is to consider the extent to which hazards are natural.

1. Natural hazards: such as earthquakes or floods arise from purely natural processes in the environment.

2. Quasi-natural hazards: such as smog, acid rain arise through interaction of natural processes and human activities.

3. Technological (or manmade) hazards: such as the toxicity of pesticides to fauna, accidental release of chemicals or radiation from a nuclear plant. These arise directly as a result of human activities.

According to Hewitt and Burton (1971) the hazards can be classified as follows.

1. Natural hazard

a. Atmospheric hazard

i. Excess rainfall

ii. Heavy snowfalls

iii. High wind speeds

iv. Extreme temperatures

v. Hurricanes

vi. Thunderstorms

vii. Tornadoes etc

b. Hydrological hazards

i. Floods – rivers and coastal

ii. Drought etc

c. Geological

i. Landslides

ii. Avalanches

iii. Earthquake

iv. Volcanic eruption etc

d. Biological

i. Epidemic in humans

ii. Epidemic in plants

iii. Epidemic in animals

iv. Locusts etc

2. Manmade hazards

a. Transport accidents

b. Industrial explosions/fires

c. Accidental release of toxic chemicals

d. Nuclear accidents

e. Collapse of public buildings etc

Hazards can also be classified as

a. Primary hazards: primary hazards are immediate and pose direct threat to mankind or his surroundings. Example: heavy rains which cause flooding of rivers.

b. Secondary hazards: secondary hazards occur as a result of primary hazards. Example – dam failure due to floods.

[iv]An environmental hazard is a substance, state or event which has the potential to threaten the surrounding natural environment / or adversely affect people's health, including pollution and natural disasters such as storms and earthquakes.

Any single or combination of toxic chemical, biological, or physical agents in the environment, resulting from human activities or natural processes, that may impact the health of exposed subjects, including pollutants such as heavy metals, pesticides, biological contaminants, toxic waste, industrial and home chemicals.^[1]

Human-made hazards while not immediately health-threatening may turn out detrimental to man's well-being eventually, because deterioration in the environment can produce secondary, unwanted negative effects on the human ecosphere. The effects of water pollution may not be immediately visible because of a sewage system that helps drain off toxic substances. If those substances turn out to be persistent (e.g. persistent organic pollutant), however, they will literally be fed back to their producers via the food chain: plankton -> edible fish -> humans. In that respect, a considerable number of environmental hazards listed below are man-made (anthropogenic) hazards.

Hazards can be categorized in four types:

1. Chemical

2. Physical (mechanical, etc.)

3. Biological

4. Psychosocial.

Chemical[edit]

Chemical hazards are defined in the Globally Harmonized Systemand in the European Union chemical regulations. They are caused by chemical substances causing significant damage to the environment. The label is particularly applicable towards substances with aquatic toxicity. An example is zinc oxide, a common paint pigment, which is extremely toxic to aquatic life.

Toxicity or other hazards do not imply an environmental hazard, because elimination by sunlight (photolysis), water (hydrolysis) or organisms (biological elimination) neutralizes many reactive or poisonous substances. Persistence towards these elimination mechanisms combined with toxicity gives the substance the ability to do damage in the long term. Also, the lack of immediate human toxicity does not mean the substance is environmentally nonhazardous. For example, tanker truck-sized spills of substances such as milk can cause a lot of damage in the local aquatic ecosystems: the added biological oxygen demand causes rapid eutrophication, leading to anoxic conditions in the water body.

All hazards in this category are mainly anthropogenic although there exist a number of natural carcinogens and chemical elements like radon and lead may turn up in health-critical concentrations in the natural environment:

· Anthrax

· Antibiotic agents in animals destined for human consumption

· Arsenic - a contaminant of fresh water sources (water wells)

· Asbestos - carcinogenic

· DDT

· Carcinogens

· dioxins

· Endocrine disruptors

· Explosive material

· Fungicides

· Furans

· Haloalkanes

· Heavy metals

· Herbicides

· Hormones in animals destined for human consumption

· Lead in paint

· Marine debris

· mercury

· Mutagens

· Pesticides

· Polychlorinated biphenyls

· Radon and other natural sources of radioactivity

· Soil pollution

· Tobacco smoking

· Toxic waste

· Radon

Physical[edit]

A physical hazard is a type of occupational hazard that involves environmental hazards that can cause harm with or without contact.

· Cosmic rays

· Drought

· Earthquake

· Electromagnetic fields

· E-waste

· Floods

· Fog

· Light pollution

· Lighting

· Lightning

· Noise pollution

· Quicksand

· Ultraviolet light

· vibration

· X-rays

Biological[edit]

Biological hazards, also known as biohazards, refer to biological substances that pose a threat to the health of living organisms, primarily that of humans. This can include medical waste or samples of a microorganism, virus or toxin (from a biological source) that can affect human health.

· Allergies

· Arbovirus

· Avian influenza

· Bovine spongiform encephalopathy (BSE)

· Cholera

· Ebola

· Epidemics

· Food poisoning

· Malaria

· Molds

· Onchocerciasis (river blindness)

· Pandemics

· Pathogens

· Pollen for allergic people

· Rabies

· Severe acute respiratory syndrome (SARS)

· Sick building syndrome

See also: Toxicology and List of allergies

Psychosocial Hazards[edit]

Psychosocial hazards include but aren't limited to stress, violence and other workplace stressors. Work is generally beneficial to mental health and personal wellbeing. It provides people with structure and purpose and a sense of identity.

[i] https://www.safeopedia.com/definition/152/hazard.

[ii] https://simple.wikipedia.org/wiki/Environment

[iii] http://www.adpc.net/casita/course-materials/Mod-2-Hazards.pdf

[iv] https://en.wikipedia.org/wiki/Environmental_hazard

General characters and classification of Siphonaptera

2018-03-14T21:24:00.001+05:30

Siphonaptera[i]

Ø CLASSIFICATION^[ii]

· Kingdom – Animalia (Animals)

· Phylum – Arthropoda

Body have jointed appendages, divisible into head, thorax and abdomen, head bears antenna and eye may be compound or simple (ocelli), the joints are covered by arthroidal membrane.

· Subpphylum – Hexapoda

Walking appendages are reduced to six with three body segments

· Class – Insecta

Body segmented into head thorax and abdomen, head composed of six segments, Thorax is composed of 3 segments (pronotum, mesonotum, metanotum), abdomen upto 11 segments or more.

· Order - Siphonaptera

Ø The Siphonaptera is a monophyletic[1] group of some 2000 species.

Ø All adults of which are highly modified, apterous[2] and laterally compressed ectoparasites[3] of birds and mammals.

Ø The mouth parts are modified for piercing and sucking, without mandibles. The gut has a salivary pump[4] and a pharyngeal pump[5] and a cibarial pump[6].

Ø Compound eyes are absent and ocelli[7] may be absent to well developed.

Ø The body has many backwardly directed spines, some may be grouped into combs and are called ctenidia, which may be present on gena[8] and thorax (especially the prothorax).

Figure 1: Showing difference between monophyletic, polyphyletic and paraphyletic[iii]

Ø The metathorax is large and houses hind leg muscles, which power the prodigious[9] leaps made by these insects. The legs are long and strong, terminating in strong claws for grasping host hairs.

Ø Large eggs are held in the host’s nest, where free-living worm-like larvae develop on material such as skin debris shed from the host.

Ø The larvae are pale legless worm-like, body is covered with sparse bristles; head reduced, eyeless, with chewing mouthparts.

Ø High temperature and moisture are required for development of most of the fleas. Including those on domestic cats (Ctenocephalides felis), dogs (C. Canis) and humans (Pulex irritans).

Ø The pupa is exarate[10] and adecticous in a loose cocoon.

Figure 2: showing type of pupa[iv]

Ø Adults of both sexes are hematophagous (take blood from host).

Ø Some species are monoxenous[11].

Ø The plague flea (Xenopsylla cheopis) is polyxeny[12] and facilitates transfer of plague from rat to human host.

Ø Fleas transmit some other diseases of minor significance from other mammals to humans, including murine typhus, tularaemia, but apart from plague, the most common human health threat is from allergic reaction to frequent bites from the fleas of our pets C. felis and C. Canis.

Ø Remarks[v], [vi]

· The laterally flattened body allows easy movement among the host’s fur, feathers or hairs.

· Backwardly pointed bristles prevent fleas from falling of or being easily captured by the host.

· Some fleas can jump 200 times their body length

· Fleas only infest animals that have a regular nest site, which is why most rodents have fleas.

Footnotes

[1] It is a group of organisms descended from a common evolutionary ancestor or ancestral group, especially one not shared with any other group.

[2] An insect having no wings

[3] A parasite, such as a flea, that lives on the outside of its host.

[4] To inject saliva into the wound.

[5] For sucking up the blood.

[6] In hematophagous insects, the cibarial pump is a structure associated with a complex of muscles located in the head. It controls the ingestion of blood from the host and transfers it to the gut.

[7] Simple eye

[8] Part of head

Footnotes

[9] Unusual/abnormal

[10] Grooved or furrowed pupa having the appendages not cemented to the body, see figure 2

Footnotes

[11] Restricted to one host

[12] Parasitizes more than one host

References/Further study

[i] Gullian PJ, Cranston PS, The insects: an outline of entomology, fifth edition, Wiley Blackwell, Chennai, India.

[ii] Aphaniptera Shipley 1904. Zool. Anz. 27:260

[iii] 1999, Addison Wesley Longman, Inc.

[iv] https://www.phrygane.tk/natural-enemies/imaginal-or-adult-phase.html

[v] American Insects: A Handbook of the Insects of America North of Mexico, Ross H. Arnett. 2000. CRC Press.

[vi] https://bugguide.net/node/view/7040

Determination of Lactose percentage in Milk sample (Benedict's Method)

2018-01-13T15:32:00.000+05:30

1. MATERIALS REQUIRED

A. Milk sample

B. Beaker (50 ml, 100 ml, 250 ml)

C. 0.5 N H₂SO₄

D. Sodium tungestate

E. Burette

F. Benedict’s reagent

G. Sodium carbonate

2. PRINCIPLE

Lactose is synthesized within the alveolar cells of mammary gland from material extracted from blood. The normal content of lactose in milk is 4.5-5%. Any depression of the synthesis of lactose is accompanied by increase in the concentration of sodium and chloride ion to keep the osmotic pressure of the milk in equilibrium with that of the blood and therefore the milk tastes salty.

Dominating sodium and chloride ion in milk indicates mastitis (Inflammation of the mammary gland in the breast or udder) typically due to bacterial infection.

3. PROCEDURE

· Take 5 ml of milk sample into a volumetric flask (50 ml). add 2.5 ml of 10% sodium tungestate drop by drop with continuous mixing.

Weigh 10 g of sodium tungestate, pour it into a graduated cylinder or volumetric flast containing about 80 ml of water. Once the sodium tungestate have dissolved completely; add water to make the final voume to 100 ml

· Add 5 ml of 0.5N sulphuric acid with continuous mixing

· Finally make volume to 50 ml with distilled water

· Leave the mixture in the flask for 10 minutes and then filter.

usually the lactose is dissolved in water (clear)

· Transfer the filterate to a burette

· In another beaker, put 25 ml of benedict’s reagent with 30 ml of distilled water and 2 gm of anhydrous sodium carbonate.

· Mix well the mixture and heat till the solution becomes clear - while the solution is boiled, proceed titration, firstly rapidly by 2 ml till first shade of reduction is obtained.

· Then proceed with titration drop by drop till complete reduction of blue colour.

Disappearance of blue colour and appearance of reddish brown colour (of cuprous thiocynate)

· Record the volume (ml) of filterate exhausted in the titration (R)

4. CALCULATION

Every 25 ml of Benedict’s solution is reduced by 0.0678 gm of lactose.

FORMULA FOR CALCULATING CONCENTRATION OF PLANT EXTRACTS

2016-12-11T19:02:00.002+05:30

Hello there!!!!
i have prepared an excel sheet in Excel - 2007, which can be used to calculate the concentration of the plant extracts in mg/ml.

calculate concentration

to go to the excel sheet for downloading or calculating

GENERAL CHARACTERS OF RADIATA

2016-08-25T00:48:00.001+05:30

SUPERPHYLUM RADIATA

The radiata is a superphylum which includes both the echinoderms, cnidarians and ctenophores and is not part of the usual classification system and is not used by the biologists. The group includes radially symmetric animals of Eumetazoa[1]. The echinoderms, however, are members of the Bilateria, because they exhibit bilateral symmetry in their developing stages. Their radial symmetry is secondary.

In 1983 Thomas defined a sub-kingdom called Radiata Consisting of the phyla porifera, myxozoa, placozoa, cnidaria and ctenophore (that is, all the animals that are not in bilateria). The five kingdom classification of Lynn Margulis and K. V. Schwartz keeps only Cnidaria and Ctenophora in Radiata.

We will deal hear with the Cnidaria and Ctenophora with respect to their general characters.

COELENTRATA (OR CNIDARIA)

The cnidarians[2] are an aquatic group of organisms, commonly known as hydroids, jellyfish, sea anemone and corals. They are tentacle bearing, radial or biradial animals with sac-like body composed of two basic cell layers. The inner layer of cells, called the gastrodermis, lines the hollow space, the coelenterons, which functions in digestion and transport and into which there is single opening, the mouth. The outer cell layer consists of an epidermis. The gastrodermis and epidermis are separated by a thin, acellular matrix or mesolamella or by a jelly-like material containing cells called the mesoglea or mesenchyme.

All Cnidaria are constructed from eight basic cell types – epithelial, muscular, nervous, glandular, reproductive, interstitial, mesenchyme and cnidoblasts. Cnidoblasts are most frequently present on tentacles and contain stinging structures – the nematocysts which function in defence and in the capture of food; all cnidarians are carnivorous in habit.

All cnidarians have tissue level of organization having, epiderma, nervous, digestive and muscular tissues, but lacking specialized organ system. Fundamentally two body forms are repre: Polyp and Medusa (we will talk about these later)

EXTERNAL MORPHOLOGY

Coelenterates are a acoelomate and radially symmetrical lower invertebrates (Radiata). The coelenterates are represented by two morphologically different types of individuals, polyps and medusa.

Polyps are sessile with a tubular body (eg. Hydra, Metridium (Sea anemone))

Medusa are free swimming umbrella or bell-shaped body.

Some coelenterates pass through both stages in their life cycle with an alternation of generations.

INTERNAL STRUCTURE

Internal structure of Cnidarians can be understood by studying the histology of Hydra.

GASTROVASCULAR CAVITY

Almost all cnidarians have a central cavity called coelenterons, functionally referred to as gastrovascular cavity. It has only one opening – the mouth. There is no anus and no excretory pore. The undigested food and wastes exit the cavity through the mouth opening.

BODY WALL

There body wall is composed of two layers of cells, outer layer is called epidermis and the inner layer is called gastrodermis/endodermis. The two layers are separated from each other by a thin delicate, non-cellular gelatinous layer called mesoglea or supporting lamella.

1. EPIDERMIS

The epidermis is composed of small, more or less cuboidal cell. It is a protective and sensory layer. The epidermis is covered externally by a thin coating of cuticle. It has various types of cells as follows.

a. Epithelio-muscle cells

Most of epidermis is composed of epithelio-muscle cells that helps in both muscular contraction and epithelial covering. The epithelial part extends up to body surface and the basal muscular part is drawn out into two muscle processes along the longitudinal axis. Muscle process contains contractile fibril, the myoneme.

b. Gland cells

These are tall cells found chiefly on pedal disc and around mouth region. These secrete a mucus-like sticky material which serves for attachment and protection.

c. Interstitial cells

They are present in the interstitial spaces between epithelio-muscle cells. They are small round undifferentiated cells and are capable of developing any other kind of cells, such as reproductive, glandular, stinging etc.

d. Cnidoblasts

Many of the interstitial cells of epidermis develop into specialized cells called cnidoblasts. These are specially present on the tentacles arranged in clusters or batteries. They are oval shaped cells with basal nucleus and possess a sac-like organoid – the nematocyst. It is like a capsule enclosing a coiled tube or thread.

e. Sensory cells

They occur scattered throughout the epidermis among epithelio-muscle cells and are specially found on tentacles, hypostome and pedal disc.

f. Nerve cells

Throughout the evolutionary trend, true nerve cells or ganglion cell occurs for first time in coelenterates. They are derived from interstitial cells of epidermis. They occur at the base of epithelio-muscle cells just above their muscle processes..

g. Germ cells

During summer, interstitial cells of some regions of body, divide repeatedly and proliferate like reproductive cells forming gonads, which later differentiate into testes and ovaries.

2. GASTRODERMIS

The coelenterons is internally lined by gastrodermis. It is formed chiefly of large, columnar cells. This layer is mainly nutritive in function. The gastrodermis is composed of following types of cells.

a. Endothelio-muscle or nutritive cells

These are most abundant cells forming bulk of gastrodermis. These resemble the epithelio-muscle cells of epidermis except that their basal contractile processes are single, more delicate and oriented at right angles to the processes of the epithelio-muscle cells. There contraction reduces the diameter of the body and tentacles, which becomes narrower and longer.

The free end may bear two whip-like flagella and blunt pseudopodia like projections. The movement of flagella keeps the food in the coelenterons in motion. The pseudopodia like projections can engulf food particles.

b. Endothelial-gland cells

They are smaller than nutritive cells and occurs scattered among nutritive cells. They lack muscle tails at basal end, but may bear one or two flagella. The gland cells are absent in the tentacles. They are of two types.

· Enzymatic gland cells: secrete digestive enzymes into gastrovascular cavity for extracellular digestion.

· Mucous gland cells: secrete a slimy fluid serving as lubricants.

c. Interstitial cells

A few interstitial cells occur between the bases of nutritive cells. These are totipotent cells and thus can transform into all other type of cells.

d. Sensory cells

Sensory cells are found in between nutritive cells. They are supposed to be stimulated on entry of prey into gastrovascular cavity.

e. Nerve cells

These are similar to those present in epidermis, except that they are present here in fewer no. than epidermis.

3. MESOGLEA

It is non-cellular thin layer secreted by both epidermis and endodermis and separates the epidermis and gastrodermis. It serves for attachment of cellular layers.

TO BE CONTD…..

[1] Eumetazoa is a clade which includes all major animal phyla

Technorati Tags: CNIDARIA,RADIATA,CTENOPHORA

except sponges.

[2] Cnidos, thread; Gk

Giardiasis: General Introduction

2016-08-22T15:25:00.000+05:30

1. INTRODUCTION

Giardiasis (popularly known as beaver fever)[i] is a zoonoticparasitic disease caused by the flagellate protozoan Giardia lamblia(also sometimes calledGiardia intestinalis and Giardia duodenalis).[ii] The Giardia inhabits the small intestine of its host(variety of domestic and wild animals species, as well as humans). It is attached to the surface of columnar epithelial cells of intestine. It may penetrate down into the secretory tubules of mucosa and may also be found sometimes in the gall bladder and biliary drainage. It is one of the most common pathogenic parasitic infections in humans worldwide; in 2013, there were about 280 million people worldwide with symptomatic giardiasis.

2. HISTORY

The trophozoite form of Giardia was first observed in 1681 by Antonie van Leeuwenhoek in his own diarrhea stools. The genus was chosen to honour Professor Alfred Mathieu Giard of Paris. In 1998, a highly publicised Giardia and Cryptosporidium outbreak was reported in Sydney, Australia, but it was found to be due to mismeasurement of the concentrations of microbes in the water supply. A 2004 outbreak in Bergen (Norway) hastened work on adding UV treatment to the water facilities[iii]. In 2008, Giardia was identified as one of the causes of the dysentery [1] afflicting Crusaders in Palestine in the 12th and 13th centuries.

3. CAUSATIVE AGENT

Giardia lamblia exists in two forms

a. The trophozoite: it is a pear-shaped and motile organism. It is 10-20 micrometer long and 7-10 micrometer in diameter. The body is tear drop shaped with convex dorsal. The trophozoite possess 8 flagella and two nuclei. The anterior portion of ventral surface of the organism is modified to form a sucking disc which serves for attachment of organism.

b. The cyst: the cyst is oval and measures 8-14 micrometer in length and 7-10 micrometer in width. It has four nuclei, flagella and blepharoplast. The cyst is smooth and colourless. It represents the resting stage of organism. Its rigid outer wall protects the organisms from unfavourable conditions. It has been observed that the cyst hatches only after exposure to acidic conditions of stomach.

4. SOURCE OF INFECTION AND TRANSMISSION

Giardia lamblia is transmitted through fecal-oral route with the ingestion of cysts. Primary route are personal contact and contaminated water and food. The cyst is transmitted from individual to individual by water and food contaminated by faecal matter. After the cyst is ingested, its cytoplasm differentiates into two motile, fully formed trophozoites. These then come out of the cyst wall and attach themselves to the epithelial surface of the small intestine. Subsequently they multiply by binary fission.

Within days after infection, millions of trophozoites develop. These may completely cover a party of epithelial surface of small intestine. Giardia lamblia is not considered as tissue parasite, but its ability to adhere closely to the columnar cells at the level of microvilli results in antigenic stimulations of the host. The cysts are formed in the small intestine.

5. SYMPTOMS

Symptoms might include watery diarrhoea alternating with greasy stools. Fatigue, cramps and belching gas also may occur. Some people have no symptoms.

People may experience:

Pain areas: in the abdomen

Gastrointestinal: diarrhoea, belching, bloating, indigestion, nausea, passing excessive amounts of gas, vomiting, or flatulence

Whole body: fatigue, loss of appetite, malaise, or malnutrition

Also common: cramping, failure to thrive, malodorous stool, or weight loss

6. PREVENTION/PROPHYLAXIS

Proper maintenance of water supply systems. Washing of hands and avoiding potentially contaminated food and untreated water.

7. TREATMENT

Giardia lamblia is difficult to diagnose, which often leads to delay in treatment or misdiagnosis. Several tests should conducted over one-week period for proper detection. The Giardia lamblia infection can be diagnosed by examination of stool for motile trophozoites or for distincitive oval cysts of Giardia lamblia. Modern tests like ELISA are capable of detecting even minor infections of Giardia lamblia.

Treatment is not always necessary, since the infection usually resolves on its own. However if infection is acute or symptoms persists then nitroimidazole medication is used such as metronidazole, tinidazole, secnidazole or ornidazole.

During pregnancy, paromomycin is preferred treatment drug because of its poor intestinal absorption and thus less exposure to the foetus.

[1] Dysentery, is a type of gastroenteritis, that results in diarrheawith blood

[i] "Giardiasis (beaver fever)". New York State Department of Health. October 2011. Retrieved21 June 2015.

[ii] Esch KJ, Petersen CA (January 2013). "Transmission and epidemiology of zoonotic protozoal diseases of companion animals". Clin Microbiol Rev.26 (1): 58–85.

[iii] Nygård K, Schimmer B, Søbstad Ø, Walde A, Tveit I, Langeland N, Hausken T, Aavitsland P (2006). "A large community outbreak of waterborne giardiasis-delayed detection in a non-endemic urban area". BMC Public Health. 6 (1): 141. doi:10.1186/1471-2458-6-141. PMC 1524744. PMID 16725025.

AMOEBIASIS: GENERAL INTRODUCTION

2016-08-10T21:38:00.001+05:30

1. INTRODUCTION

Amoebiasis is also known as entamoebiasis. It is an infection caused by any of the amoeba of the Entamoeba group. But the symptoms are most common on infection of Entamoeba histolytica. Amoebiasis can be present with no, mild or severe symptom. Symptoms may include abdominal pain, mild diarrhoea, bloody diarrhoea or severe colitis[1] with tissue death and perforations.

2. HISTORY

The most dramatic incident was Chicago World’s Fair Outbreak in 1933 in USA. It was caused by contaminated drinking water; defective plumbing. There were 100 cases (with 58 deaths).

In 1998 there was an outbreak of amoebiasis in the republic of Georgia; 188 cases were reported, including 71 cases of intestinal amoebiasis and 106 probable causes of liver amoebiasis.

3. CAUSATIVE AGENT

In humans for species of Genus Entamoeba have been reported to cause amoebiasis – E. gingivalis, E. coli, E. hartmanni, E. histolytica.

E. histolytica has world wide distribution. It parasitizes various primates and rodents. It inhabits the lumen and mucosa of large intestine, predominantly colon. It is capable of invading virtually any tissue and organ of the body. The most predominantly infected organ other than colon is liver. The cystic stage is formed in the lumen of gut and occurs in the stool of chronic dysenteric patients and carriers.

4. SOURCE OF INFECTION AND TRANSMISSION

It is usually transmitted by the fecal-oral route, but it can also be transmitted indirectly through contact with dirty h ands or objects. Infection is spread through ingestion of the cyst form of the parasite[2]. Any non-encysted amoeba, or trophozoites[3] , die quickly after leaving the body but may also be present in stool – these are rarely the source of new infection. Members of both sexes of human are infected by this parasite. There is, however, a higher prevalence of amoebiasis in adult males in the agricultural occupation who have increased risk of exposure.

5. SYMPTOMS

Most infected people (about 90%) are asymptomatic, but this disease has the potential to make sufferer dangerously ill. It is estimated that about 40,000 to 100,000 people die annually worldwide due to amoebiasis[i]. Infection can sometimes last for years. Symptoms can develop after days or few weeks of infection. But usually it is about two to four weeks. Symptoms can range from mild diarrhoea to severe dysentery with blood and mucus. The blood comes from lesions formed by the amoeba invading the lining of large intestine. In about 10% infection the amoeba enters the bloodstream and may travel to other organs in the body. Most commonly liver is infected[ii]. In asymptomatic infection the amoeba lives by eating and digesting bacteria and food particles in the gut[4]. It does not usually come in contact with the intestine. Disease occurs when amoeba comes in contact with the intestinal lining. Amoeba secrets the same enzyme and destroys the mucosa and ingests the destroyed cells. Theoretically the ingestion of one viable cyst can cause amoebiasis.

6. PREVENTION/PROPHYLAXIS

Wash hands thoroughly with soap and hot running water for at least 10 seconds after before handling food.

Clean bathrooms and toilets often, pay particular attention to toiled seats and taps.

Avoid sharing towels or face washers.

Avoid raw vegetables when in endemic areas, as they may have be fertilized using human faeces.

Boil water or treat with iodine tablets.

Avoid eating street foods, especially in public areas where others are sharing sauces in one container.

7. TREATMENT

E. histolytica infection occurs in both the intestine and tissues of intestine or liver. So two different classes of drugs are needed. One for each location. Thus there are two major components of treatment.

* Elimination of tissue invading organisms

* Elimination of organisms from the lumen of intestine

The drugs commonly used are:

Iodoquinol

Metronidazol

Emetine

[1] Inflammation of colon

[2] A semi dormant and hardy structure found in faeces.

[3] a growing stage in the life cycle of some sporozoan parasites, when they are absorbing nutrients from the host

[4] the stomach or belly.

[i] Atlas of human infection diseases, first edition. Heiman F. L. Wertheim, Peter Horby and John P. Woodall., 2012, Black well publishing ltd.

[ii] Nespola e tal., 2015, First case of amebic liver abscess 22 years after first occurrence. Parasite 22: 20

TYPHOID

2016-08-01T08:18:00.002+05:30

1. HISTORY

In 430 BC, a plague, which some believed to have been typhoid, killed one-third of the population of Athens, including the leader Pericles. Some historians believe that English colony of Jamestown Virginia, died out due to typhoid. Typhoid fever killed more than 6000 settlers in new from 1607 to 1624 [43]. During the Spanish-American war, American troops were exposed to typhoid fever due to inadequate sanitation system. Consequently more soldiers died of typhoid than the war wounds.

The most notorious incident of typhoid was Mary Mallon (a cook in New York), also known as typhoid marry. She was the first carrier of typhoid in USA in 1907. She was found to be closely associated with 53 typhoid cases and 3 deaths [47]. The public health authorities asked Mary to quit her job or have her gall bladder removed, as she had chronic infection that kept her active as a typhoid disease carrier. Mary quit her job but returned late under a false name. But she was detained and quarantined after another typhoid outbreak. She died of pneumonia after 26 years of quarantine[i].

2. CAUSATIVE AGENT

It is caused by Salmonella typhi. However, the organisms like Salmonella paratyphi and Salmonella schottmilleri may also cause this disease. The Salmonella vary in length. Most of these are motile and have peritrichous flagella. They grow readily on simple media.

3. SOURCE OF INFECTION AND TRANSMISSION

The bacterial infection takes place through food and water contaminated by human faeces. The infection my occur through milk and other dairy products. The infectious dose seems to be quite high and may be more than 10⁵ organisms. In areas with very poor sanitation, the bacteria may get transmitted through house flies.

4. SYMPTOMS

The salmonella reach the small intestine and from there they penetrate the epithelial lining. Then the bacteria are phagocytozed by the macrophages, within which they actively multiply. The macrophages transmit the salmonellae throughout the body. These even occur during first week of infection which is accompanied by fever, aches and pains.

Extended bacteremia[ii] occurs in the second week. Generally the gall bladder becomes infected. From the gall bladder the bacteria may shed into the intestinal lumen. During this time, ulcerative lesions (rose spots) appear on the lower chest and abdomen in some patients.

In untreated cases, the patients is exhausted by the third week.

After people recover from clinical disease, the S. Typhi may continue to multiply in the gall bladder, who may become chronic carrier and serve as source of future typhoid outbreaks.

Upto 10% of patients may die of this disease.

5. PREVENTION

a. Proper sewage treatment

b. Pasteurization of milk

c. Vaccines: although killed vaccines have been used for many years, they are of limited value. The vaccine reduces the chances of getting typhoid disease to 30-70 %.

6. TREATMENT

Antibiotics like ampicillin and chloramphenicol are used for the treatment of typhoid fever. Treatment must be continued for several weeks to ensure killing of bacteria that becomes sequestered[iii] in the body.

Trimethoperim, sulfamethoxazole and mumoxillin are excellent alternatives to ampicillin.

REFERENCES/FURTHER STUDIES

1. Sobti, R. C., Medical Zoology

2. Byrne, Joseph Patrick (2008), Encyclopedia of pestilence, pandemics and plagues: ISBN 0-313-34102-8

3. Nova: the most dangerous women in America

[i] A state or place of isolation in which people or animal exposed to infectious diseases is placed.

[ii] the presence of bacteria in the blood

[iii] Isolated and hidden away.

REPRODUCTION IN ORGANISMS: AN OVERVIEW

2016-07-22T15:27:00.001+05:30

Reproduction is defined as a biological process in which an organism gives rise to young ones, similar to itself. The offspring grow, mature and in turn produce new offspring. Thus there is a cycle of birth, growth and death.

Broadly classifying, the reproduction is of two types

1. ASEXUAL REPRODUCTION: when the reproduction involves only one parent and the reproduction takes place without formation of gametes. Then the reproduction is known as asexual reproduction.

· As a result the offspring are not only identical to one another but are also exact copies of their parent.

· Asexual reproduction is common among different group of single celled organisms, and in plants and animals with relatively simple organisation.

· In single celled organisms, cell division is itself a mode of reproduction.

DIFFERENT MODES OF SEXUAL REPRODUCTION

· BINARY FISSION: it is a type of sexual reproduction in which the parent cell divides into two daughter cells. Ex. Amoeba, Paramecium

· BUDDING: A small bud is formed in the parent cell, which primarily remains attached to the parent and then after attaining ability to remain independently, the bud detaches form the parent cell. Ex Yeast.

· In fungi and algae, specialized asexual reproductive structures are formed.

Zoospore in algae

Conidia in Penicillium

Buds in Hydra

Etc

· VEGETATIVE REPRODUCTION/PROPAGATION

In plants the asexual reproduction is rather called as vegetative propagation. In plants vegetative propagation such as runner, rhizome, sucker, tuber etc

2. SEXUAL REPRODUCTION: it involves two parents and formation of male and female gametes either by same individual or by different individuals of opposite sex. The gametes fuse to form zygote which develops to form new organisms. Because of fusion of male and female gametes which results into the fusion of two different genetic combination, the offspring produced are not identical to their parents.

The sexual reproduction has different phases

· Juvenile phase: it is a period of growth and maturity of an organism before it can reproduce sexually.

· Reproductive phase: it is a period in which organism can reproduce sexually.

Easily seen in higher plants, when they come to flower

Some plants flower seasonally and some throughout the year

Few plants exhibit unusual flowering phenomenon.

For eg. Bamboo species flower only once in their life time, Neelakurinji (Tamil Nadu) flower only once in 12 years, (the latest being September, 2006)

In animals, sexual reproduction is usually seasonal.

In placental mammals there is occurrence of cyclical changes in the activities of ovaries and accessory organs.

· SENESCENT PHASE: it is a phase in which reproductive phase ends, and old age ultimately leads to death of the organism.

EVENTS IN SEXUAL REPRODUCTION:

1. PRE-FERTILIZATION EVENTS:
a) GAMETOGENESIS

The gametes are usually haploid
Gametes called homogametes / isogametes when both have same appearance.
When gametes are different, they are called heterogametes; male gamete known as antherozoid /sperm, female is called ovum / egg.
Bisexual organisms called as homothallic / monoecious whereas unisexual organisms called heterothallic / dioecious.

b)GAMETE TRANSFER

In most of the organisms, male gametes are motile & female gametes are stationary.
In algae, bryophytes & pteridophytes water is the medium for gamete transfer.
Pollination is the method of gamete transfer in higher plants as pollen grains are carriers of male gametes.

2. SYNGAMY / FERTILIZATION:

Syngamy results in formation of a diploid zygote.
In certain animals, female gamete develops into the adult organism without fertilization; such a process is called parthenogenesis - seen in rotifers, lizards turkeys etc.
Fertilisation may be external or internal

EXTERNAL FERTILIZATION
Syngamy occurs outside the body of the organism

Large numbers of gametes are released in the surrounding medium.
Ex. Bony fishes and Amphibians.

INTERNAL FERTILIZATION
Syngamy occurs inside the body of the organism

Numbers of ova produced are less, but large numbers of male gametes are released and they travel towards the ovum.
Ex. Birds and Mammals.

3. POST FERTILIZATION:

Events in sexual reproduction after the formation of zygote
Zygote – vital link that ensures continuity of species between organisms of one generation and the next.
Development of zygote depends on

- the type of life cycle of the organisms.
- the environment it is exposed to.

Zygote develops into embryo.

Embryogenesis involves:
- cell division to increase the number of cells
- cell differentiation for the formation of different kinds of tissues

Based on whether the development of zygote occurs inside or outside the body of the female parent, animals are categorized into oviparous and viviparous.

OVIPAROUS

These animals lay eggs.

The fertilized eggs have a calcareous shell to protect them from harsh environment.

VIVIPAROUS

These animals give birth to young ones

Embryo protected inside the mother’s body.

In flowering plants the zygote formed inside the ovule; zygote develops into embryo after which the ovule becomes the seed and ovary becomes the fruit.

Potable Water - Sources and Methods of Purification at Domestic level

2016-07-22T15:27:00.000+05:30

MANOJ KUMAR

POTABLE WATER:

Water which has been filtered cleaned or treated to meet the standards of drinking water and is reasonably clear for contaminants and harmful bacteria are considered as potable water.

Potable water access is crucial and people in developed countries may not worry where they get potable water from. They may simply turn ON their taps and get potable water. But the people in developing countries have very limited access to potable water.

Most non-potable water will be raw and untreated, which may contain unknown contaminants. It is possible for non-potable water to taste normal but carry health risks.

STANDARDS FOR POTABLE WATER IN

INDIA

According to BIS (Bureau of Indian Standards, 2012) potable water is water intended for human consumption for drinking and cooking from any source. The following table shows the parameters, their upper limit as per BIS and possible impacts on health.

TABLE – 1: SHOWING PARAMETERS, THEIR APPROVED UPPER LIMITS AS PER BIS AND POSSIBLE HEALTH HAZARDS (as per BIS water quality standards, 2012)

parameters	upper limits as per BIS standards	possible health risks
total dissolved solid	200 mg/L	GI irritation, Bad taste
pH	6.5 - 8.5	affects mucous membrane, bitter taste
alkalinity	600 mg/L	boiled rice turns yellowish
hardness	600 mg/L	poor lathering with soap, skin irritation, boiled meat/food becomes poor quality
Ca	200 mg/L	deteriorates clothes, pipe incrustation
Mg	100 mg/L	deteriorates clothes, pipe incrustation
Fe	1.0 mg/L	cloth staining, bitter taste
Mn	0.3 mg/L	poor taste, staining of clothes
Al	0.2 mg/L	neurological disorders, Alzheimer disease
Cu	1.5 mg/L	liver damage
Zn	15 mg/L	vomiting, abdominal pain
Ammonia	NIL	indicates pollution
Nitrite	NIL	forms nitrosoamine which is carcinogenic
Nitrate	100 mg/L	blue baby disease
Sulphate	400 mg/L	GI irritation, laxative effect
Chloride	100 mg/L	corrosive to alimentary cannal
Fluoride	1.5 mg/L	dental and skeletal disorders
Hg	0.001 mg/L	minamata disease
Cadmium	0.01 mg/L	itai itai disease
Lead	0.05 mg/L	bioaccumulation, neurological disorders
Chromium	0.05 mg/L	Carcinogenic
Pesticides	0.001 mg/L	affects CNS
detergents	NIL	undesirable foaming

3. SOURCES OF POTABLE WATER:

As per the Indian Census, 2011 the potable water sources in India and their comparative shares in household potable water consumption is as follows.

TABLE 2: SHOWING VARIOUS SOURCE OF POTABLE WATER AND THEIR PERCENTAGE SHARES IN TOTAL HOUSEHOLD POTABLE WATER CONSUMPTION (as per the Indian Census Report, 2011)

SOURCE	PERCENTAGE SHARE
Tap water	43.5
Well	11.0
Hand pump	33.5
Tube well	8.5
Spring	0.5
River	0.6
Pond/Lake	0.8
Other sources	1.5

4. METHODS OF PURIFICATION OF POTABLE WATER AT DOMESTIC LEVELS

A. BOILING:

It is a satisfactory method of purifying water for house hold purposes. While using this method, the water must be brought to a 'rolling' boil. Boiling should be done for 5-10 minutes. Boiling destroys all forms of disease producing organisms usually found in water. When the water is boiled, the container becomes sterilized or the water should be boiled preferably in the same container.

B. SEDIMENTATION AND DECANTATION:

It is a natural method of water purification. In this method water is collected from the source and stored in a jar or container. The water if allowed to remain for some time in container, the impurities (e.g. stone, sand, chalk, mud, etc.) will settle down at the bottom. We will be able to pour out the water without disturbing the impurities. This process of water filtration is called sedimentation and serves the following purpose:

The solid matter in suspension falls to the bottom by gravity and is called sediment.

C. SAND FILTERATION:

This is also called the filtration of water by four pitchers system. It is old fashioned filter system. In this method, the four pitchers are placed one above the other on a wooden stand. All the vessels except the last one have small pores at the bottom. The upper most vessel contains thick layer of charcoal which is filled with water and which percolated through a hole made at its bottom, along with a piece of cloth plugged into the hole of the second pitcher.

The second pitcher contains a layer of sand, and the third contains gravel. Water drips into each of these vessels. The last or fourth pitcher contains filtered water.

Nowadays one can buy a manufactured filter from the market. The principle of these filters is that water is made to pass through porous 'candle' and in doing so it is purified.

D. CHLORINATION:

Water is most essential for the maintenance of life but it is also a vehicle for infection and responsible for severe and wide spread water borne diseases. In such a context, bacteria, helminthic, protozoal and other pathogenic infection causing cholera, diarrhea, typhoid, worm, dysentery, gardenias can be caused. It is essential to make the water safe for drinking from whatever source it is obtained. In this regard, one of the most widely used disinfectants for treating drinking water is chlorine and when it is added to water in proper proportion, it is effective in killing pathogenic organism.

E. DISTILLATION:

In the process of distillation water is heated and evaporation takes place, whereby water changes back to water when cooled; this process is called condensation. The condensed water is the purest form of water, free from microbes, and impurities.

But it loses its taste and odor. Through aeration or passing oxygen through it the water becomes consumable.

This method is quite expensive and time - consuming. But in place like laboratories, on sea-ships or places where pure water is not available, this method is found to be very useful.

F. FILTRATION:

Different varieties of filters are used to purify the water at domestic level. Filter rods (candies) are installed in the upper chamber. These rods are made of china porcelain and it is porous and hollow from the centre. When water is filled in the upper chamber it purifies and drips in the lower chamber. This water is free of any suspended matter but still has microbes in it

G. CHEMICAL METHODS OF PURIFICATION

(a) Aluminum Sulphate (b) Chlorine

In a school where a large number of students and teachers depend on the water supplied by the local civic bodies, extra measures to ensure good quality of water are needed especially when it is routed through drinking water coolers.

These water collars should be cleaned at regular periodicity and should be pilferage free. Besides, ultra-violet rays may be used for destroying micro- organism from the water without any chemical change. It has the following advantages: -

(a) Ultraviolet rays destroy all kinds of bacteria and virus, which produce diseases.

(b) Besides the boiling method, this method is safe and water can immediately be used. There is no chance of any contamination in storing it for 48 hours. Water stored in ordinary filters and pitchers provide a breeding place for the microbes.

(d) The quality of water remains intact.

(e) It has an electronic method for water purification, which is more reliable

*the data and notes have been collected from books and online contents

BIOCHEMICAL TEST FOR PRESENCE OF CARBOHYDRATE (QUALITATIVE TEST)

2015-02-07T15:13:00.001+05:30

Aim: to test the presence of carbohydrate in given sample

Materials Required: Test tube, test tube holder, sugar solution, Benedict's solution, spirit lamp.

Principle: Sugar contain aldehyde and keto-group which readily reduce metallic oxides, specially cupric to cuprous oxide. In Benedict's solution CuSO4 is mixed with sodium citrate and sodium carbonate (Na2CO3) which is more stable. In Alkaline Solution all Reducing sugars, glucose, fructose and lactose precipitate Cu2O. In acidic solution only the polysaccharides reduce cupric salt.

observation table

Experiment	Observation	Inference
Clean test tube was taken and 5 ml of Benedict’s reagent was taken in it, 3-4 drops of sample A was added to it, the mixture was thoroughly heated on spirit lamp or boiling water bath	Red or yellow of Cu₂O was formed	The given solution contains sugar monosaccharide and reducing disaccharides
Clean test tube was taken and 5 ml of Benedict’s reagent was taken in it, 3-4 drops of sample B was added to it, the mixture was thoroughly heated on spirit lamp or boiling water bath	Yellow ppt not formed	_____

Result: The solution resulted in yellow precipitate formation in sample A, hence carbohydrate is present in sample A

Therapeutic efficacy of Cinnamomum tamala (Buch.-Ham.) and Aegle marmelos (L.) leaf

2014-09-03T23:13:00.001+05:30

Sukumar Dandapat*, Manoj Kumar and M. P. Sinha

*Department of Zoology, Ranchi University, Ranchi, Jharkhand, India – 834008
*email: eaddress.sukumar27@gmail.com

Medicinal plants are widely used for therapy of various diseases and disorders due to presence of various bioactive phytochemicals. Among the studied phytochemicals polyphenol content was higher (16.7 ± 0.7 g/100g in C. tamala and 6.7 ± 0.61 g/100g in A. marmelos) and flavonoids content was lower in both plants (1.0 ± 1.01 g/100g and 0.9 ± 0.25 g/100g in C. tamala and A. marmelos respectively). Leaf extract of both plant were effective against S. aureus and P. mirabilis (6-10 mm ZOI and 100% inhibition at 0.25mg-5mg of leaf extracts in agar disk diffusion and broth dilution method respectively) and the leaf extract of both plant possess high antioxidant activity, 0.9% and 0.2% at 5μg/mL concentration 4% and 7% at 100 μg/mL concentration of A. marmelos and C. tamala leaf extracts respectively. Aqueous leaf extract of both the plants did not show cytotoxicity by haemolysis at 0.2 mg/mL-1mg/mL concentration.

NATIONAL CONFERENCE ON HARMONY WITH NATURE IN CONTEXT OF ENVIRONMENTAL ISSUES AND CHALLENGES OF THE 21ST CENTURY (HARMONY - 2014)

2014-08-13T00:17:00.000+05:30

NATIONAL CONFERENCE ON HARMONY WITH NATURE IN CONTEXT OF ENVIRONMENTAL ISSUES AND CHALLENGES OF THE 21ST CENTURY (HARMONY - 2014)

NOVEMBER

28-30

2014

Pharmacological Screening of Leaf Extract of Adhatoda vasica for Therapeutic Efficacy

2014-07-09T15:06:00.001+05:30

Global Journal of Pharmacology 8(4): 494-500, 2014

ISSN 1992-0075

© IDOSI Publications, 2014

DOI: 10.5829/idosi.gjp.2014.8.4.8419

Pharmacological Screening of Leaf Extract of Adhatoda vasica for Therapeutic Efficacy

ManojKumar, Sukumar Dandapat, Amit Kumar and M.P. Sinha

Department of Zoology, RanchiUniversity, Ranchi-834008, Jharkhand, India

Abstract: In the present study Adhatoda vasica was screened for therapeutic efficacy. The plant leaf extract was screened for phytochemicals, mineral elements, antioxidant and reducing power activity, foaming and swelling index properties. Both qualitative and quantitative analyses of phytochemicals were done. The result showed the presence of alkaloids, tannins, saponins, phenolics and flavonoids. Tannins were maximum among all the detected phytochemicals (61.38 ± 0.8 mg/g). Phenolics were minimum (1.30 ± 0.1 mg/g). Following the presence of phytochemicals the plant leaf samples were also screened for antioxidant and reducing power ability. The screening for mineral elements revealed the presence of macro and micro elements. Potassium (K), Calcium (Ca), iron (Fe), Copper (Cu), Zinc (Zn), Chromium (Cr), Vanadium and Manganese (Mn) were detected in the leaf sample. Adhatoda vasica showed highest (68070 ± 35.58 ppm) concentration of Ca. V was lowest among all the mineral elements (118 ± 6.03 pm). Since the plant contains important phytochemicals, mineral elements, antioxidant and reducing power analysis, it may be good source of future medicines.

Key words: Phytochemicals, Mineral Elements, Antioxidant, Reducing Power

Digestive System of Scoliodon

2014-07-06T22:58:00.000+05:30

The Ecoscan: volume IV (special issue); 241-246

2014-06-04T20:14:00.001+05:30

GROWTH INHIBITORY IMPACT OF ADHATODA VASICA AND VITEX NEGUNDO ON SOME HUMAN PATHOGENS

MANOJ KUMAR*, SUKUMAR DANDAPAT, AMIT KUMAR, M. P. SINHA

Zoology Department of Ranchi University, Ranchi

*e-mail: eaddress.manojkumar@gmail.com.

ABSTRACT

The present study was undertaken to determine the growth inhibitory impact of Adhatoda vasica and Vitex negundo on five human pathogens Viz. Salmonella typhi, Pseudomonas, aeruginosa, Proteus mirabilis, Bacillus subtilis, Staphylococcus aureus which are known to cause several diseases and infections in human beings such as typhoid fever, urinary tract infection, pulmonary tract infection, specticemia, pneumonia, staphylococcal scalded skin syndrome (SSSS) by agar disc diffusion method and broth dilution method. The minimum inhibitory concentration of Vitex negundo ranged from 0.612 mg/mL (Bacillus subtilis) to 5 mg/mL (Pseudomonas aeruginosa and Salmonella typhi). The minimum inhibitory concentration of Adhatoda Vasica ranged from 2.5 mg/mL (Bacillus subtilis) to 5 mg/mL (Staphylococcus aureus and Pseudomonas aeruginosa). The plants were also screened for their phytochemical contents and presence of alkaloids, tannin, saponin and flavonoids were determined. Both the plants showed growth inhibitory impact on the tested bacteria and possess potent antibacterial phytochemicals, thus Adhatoda vasica and Vitex negundo can help to discover new chemical classes.

2014-03-29T19:42:00.001+05:30

GROWTH INHIBITORY IMPACT OF VITEX NEGUNDO ON

SALMONELLA TYPHI AND PSEUDOMONAS AERUGINOSA

. Manoj Kumar*, Sukumar Dandapat, Amit Kumar and M. P. Sinha

. Department of Zoology, Ranchi University, Ranchi *e-mail: scholar.manojkumar@gmail.com

Abstract type: extended abstract

Abstract published in:

National Seminar on Values of Information Zoology

Abstract no. 69

Herbal medicines are gaining popularity in developing countries (Kumar et al, 2013), as the lifestyle is becoming more andmore stressful, people are striving to stay healthy and with the rise in cases of side effects·of synthetic medicines and evolution of multi-drug resistant (MDR) disease-causing organisms, there is an inclination towards the use of herbal medicines (Kumar et al, 2013). About 30-40 % of today's conventional medicines come from the herbal supplements, botanicals and nutraceuticals (Kumar et al, 2013).

Typhoid fever is a global infection caused by bacterium Salmonella typhi. The disease is transmitted by water, milk, fruits and vegetables that are contaminated with Salmonella typhi. It may be also transmitted by healthy carriers and infected food handlers and may be carried mechanically from feces to the food by flies. Although typhoid fever may be treated with antibiotics, the resistance of Salmonella typhi towards the antibiotics is widespread. Inrecent years there has been a rise in multi drug resistance in Salmonella typhi all over the world (Kumar et al, 2013). Pseudomonas aeruginosa is a common bacterium which is known to cause disease in animals as well as humans. It is an opportunistic pathogenfo r both plant and animal (Iglewski, 1996). Inhigher plants Pseudomonas aeruginosa is known to cause soft rot (Walker et al.,, 2004). Pseudomonas aeruginosa typically infects the pulmonary tract, urinary tract, bums; wounds and is

also known to cause blood infections (Fine et al., 1996).

The fresh leaves were collected, shade dried for 15 days, and were made to fine powder, 50 g of powder was subjected to extraction by Soxhlet extractor. The extracts were subjected to phytochemical screening, antibacterial analy sis was done against Salmonella typhl and Pseudomonas aeruginosa by agar disc diffusion method and broth dilution method.

The results of phytochemical analysis reveal the presence of alkaloids, tannins, saponins, phenols and flav6hoids. Tannin content is highest in Vitex negundo (93.9 ± 2033mg/g) and phenol content is lowest (8.1 ± 0.5 mg/g). The phytochemicals (alkaloids, phenols, tannins etc. present in the plants are responsible for their medicinal properties (Palombo, 2006). The phenols possess redox properties and th.us bestow antioxidant properties to the plants owning them; they act as hydrogen donors, reducing agents and metal chelators (Cook and Samman, 1996). Flavonoids and tannins constitute the major group o(antioxidant compounds, that act as primary antioxidants or free radical scavengers Tannins, alkaloids, saponins, flavonoids and sterols etc. ha e also been found active against pathogenic bacteria (Kennedy and Wightman , 2011).

The Vitex negundo extract was found to be effective against both bacteria, with MIC equal to 5mg/ml in broth dilution method as well as agar disc diffusion method. Zone of inhibition was 1.45 and 1.99 mm for 2.5 mg extract concentration and 3 and 4 mm for 5 mg extract concentrati on. Tannins, alkaloids, saponins, flavonoids and sterols have been found ·to have growth inhibitory impact on Salmonella typhi .Dandapat et al. attributed the antibacterial activity of Cinamomum tamala to phytochemical constituents (tannin, saponin, flavonoids, polyphenols and alkaloids) of the plant. Since the plant contains major phytochemicals (alkaloids, tannins, saponins, phenols and flavonoids) which are major contents responsible for the antibacterial properties of the plants possessing them. The antibacterial activities of Vitex negundo can be attributed to the phytochemical contents, Vitexnegundo casn be used in medicinal formulations , for eradicating Salmonella typhi and Pseudomonas aeruginosa.

PLACENTA

2014-03-10T00:45:00.000+05:30

PLACENTA

· The term placenta in its broadest sense refers to any region in viviparous organisms where maternal and foetal tissues of any kind are closely apposed, and serves as a site for physiological exchange between mother and foetus (Kent, 1987)

· Placenta is a spongy mass of flesh that absorbs nutrients and oxygen from the mother’s body.

· These nutrients and oxygen is conveyed to the developing foetus by means of umbilical cord.

· During labour the placenta is released from the uterus, because of chemical changes that occur during the delivery, and is removed from the mother by pulling the umbilical cord.

· The placenta is where the nutrients for the baby is located, while the umbilical cord serves as link between the bay and placenta.

Ø The placenta from the point of view of origin consists of two parts – Foetal placenta and Maternal placenta.

Ø The maternal placenta is furnished by single endometrium

Ø The foetal placenta is furnished by four elements – amnion, chorion, yolk sac and allantois.

Ø The amnion makes no direct contribution to the placenta, and hence can be discarded here.

Ø But from the other three membrances, the chorion makes immediate contact with the endometrium.

Ø For the formation of placenta, the chorion needs to be vascularized.

Ø This vascularization takes place by two possible ways – via yolk sac (Chorio-vitellie placenta) and via allantois (Chorio-allantoic placenta).

Ø Thus there are two basic types of placenta on the basis of origin

1. Chorio-vitelline placenta (Yolk-sac placenta): found in most marsupials, the allantois remains relatively small and never makes contact with the chorion. Yolk sac becomes large and fused broadly with chorion.

2. Chorio-allantoic or Allantoic placenta: in some marsupials (Parameles) and all eutherians, the yolk sac remains rudimentary and allantois becomes well developed and vascularized to fuse with chorion to furnish the chorion, the blood supply.

TYPES OF CHORIO-ALLANTOIC PLACENTA

On the basis of morphological characters the chorio-allantoic placenta is of following types:

1. NON-DECIDUOUS PLACENTA (OR SEMI PLACENTA):

· Implantation is superficial

· The blascocyst lies in a cavity of the uterus in contact with uterine wall.

· The intimacy of contact may be increased by formation of villi. Which penetrate into uterine wall.

· At the time of birth when parturition (separation of foetus and its membranes from mother’s body) occurs, the chorionic villi are just drawn out from the depression in the uterus.

· Found in pigs, cattle and other mammals.

2. DECIDUOUS PLACENTA ( OR PLACENTA VERA): ALSO REFFERED TO AS TRUE PLACENTA

· In this type of placenta, the intimacy between the maternal and foetal tissue is further increased.

· The wall of uterus gets eroded to various degrees and the embryonic tissues penetrate into uterine wall.

· During parturition, more or less extensive haemorrhage from the uterine wall takes place due to the injury to the endometrium which gets teared away during parturition.

· The maternal tissues are expelled out of uterus and is called as DECIDUAE.

3. CONTRA-DECIDUAE PLACENTA:

· In parameles and talpa loss of both the maternal as well as foetal tissues take place, this type of placenta is called contra deciduate placenta. The damaged maternal and foetal tissues are absorbed in-situ by the maternal leucocytes.

CLASSIFICATION OF THE BASIS OF DISTRIBUTION OF VILLI ON CHORIONIC SURFACE

1. DIFFUSE PLACENTA: found in pigs, horse, lemurs: villi remains scattered all over the surface of chorion.

2. COTYLEDONARY PLACENTA: found in cattle, deer, sheep: villi are developed in groups or patches while the rest of surface remains smooth.

3. ZONARY PLACENTA: found in carnivores – cat, dog etc: villi developed in from of belt or band around middle of chorionic sac.

4. DISCOIDAL PLACENTA: found in insectivores, bats, rabbit, dear etc: villi are restricted to circular disc or plate.

5. META DISCOIDAL PLACENTA: found in man, monkeys and apes: villi are first scattered, but later form on or two discs – monodiscoidal (in man), bidiscoidal (in monkeys and apes)

VECTOR OF MALARIA (A GENERALIZED STUDY)

2014-02-18T12:29:00.000+05:30

VECTOR OF MALARIA

Malaria or chill and fever disease is an old age human disease and is still prevailing. This disease is prevalent in all countries extending from 40⁰South to 60 ⁰ North, but the tropical zone is endemic home of al types of malaria. Malaria is caused by intracellular protozoal endoparasite belonging to genus Plasmodium. Four species of Plasmodium are responsible for causing malaria in human – P. vivax, P. Falciparum, P. malariae and P. ovale.

BIOLOGY OF VECTOR OF MALARIA

Out of about 45 species of Anopheles found in India, only few have been identified as malarial vector. They are Anopheles culicifacies, A. fluviatilis, A. minimum, A. philippinensis, A. stephensni, A. sundaicus and A. leucosphyrus.

DISTRIBUTION

They are cosmopolitan in distribution. The area of distribution of Anopheles varies with species. A. philippinensis are found in plains, A. sundaicus and A. stephensi are found in coastal regions, while A. fluviatilis inhabits the foot hill regions. Out of above mentioned species of Anopheles, A. fluviatilis is highly anthrophilic i.e. have high preference for human blood and thus are the most important vector of malaria in man.

HABITS AND HABITAT

Mosquitos are nocturnal, troublesome and irritating insect. They inhabit near human population. Only female Anopheles sucks the blood which is required for oviposition. Male Anopheles is short lived and lives on nectars of flowers and plant juices. Anopheles are known to hibernate in adult form when conditions are unfavourable. Normally they do not fly far away from their breeding grounds. But instances have been reported of Anopheles having flying range of 11 km. the life span of female Anopheles is 8-34 days, as it is on the stake of environmental conditions.

GENERAL CHARACTERS

Anopheles mosquito are thin bodied with long delicate legs, making an angle of 45 ⁰ with ground while resting. Body divisible into head thorax and abdomen.

Head lies at anteriour extremity ob body, bears a pair of large compound eyes, long palpi, a pair of antennae, long proboscis (piercing and sucking type). Male lacks the biting apparatus. The antennae in males is of bushy type (plumose) while the antennae in males is less bushy as compared to that of male.

Thorax is round and bears a pair of spotted wings and three pairs of long delicate legs, the beating of wings produce the notorious buzzing sound.

Abdomen is long, narrow and made up of ten segments, the last two segments are modified as external genitalia.

LIFE HISTORY

There are four stages – Egg, Larva, Pupa and Adult. Breeding period extends throughout the year. Copulation occurs during flying. Female lays about 80-100 eggs in early hours of morning in relatively clean and stagnant water. Each egg is boat shaped bearing lateral floats. The ganotrophic cycle (period between taking blood and laying eggs) is upto 48 hrs. egg hatches into larva within 2-3 days.

DIFFERENT STAGES OF LIFE CYCLE OF ANOPHELES MOSQUITO

Larva or wriggler is a free swimming stage. The body is divisible into head, thorax and abdomen, head bears compound eyes, antennae, and simple eye each in pairs. Thorax is segmented while abdomen is nine segmented. In 8^th segment is present respiratory siphon, and in 9^th segment four respiratory gills are present. The larva are bottom feeders. And their body lies parallel to water surface. Larval period last up to 5 – 7 days.

Pupa is coma (,) shaped, active but non feeding stage. Body divisible into cephalothorax and abdomen. A pair of small respiratory trumpets are present on the cephalothorax. 9^th abdominal segment bears a pair of paddles and each paddle bears pair of bristles. Within 7 days imago or adult mosquito emerges out from pupa.

MODE OF INFECTION

Plasmodium is digenetic (requires two hosts to complete its life cycle – man and female Anopheles). Man is the secondary host in which Plasmodium spends it asexual phase of life while female Anopheles is the definite host in which it undergoes its sexual cycle.

When a female Anopheles bites a malaria infected person, the micro and macrogametocytes from the patient enters the Anopheles’s gut, where after performing sexual reproduction zygote is formed. The motile zygote penetrates out of the gut wall to be changed into cystic stage (oocyte), inside the oocyte by the process of sporogony sporozoites are formed and thus the parasite acquires its infective stage (sporozoite). The whole process take upto 8-10 days. Such infected mosquito when bites a healthy person, the sprorzoite stage of the parasite is transmitted to the new host through the salivary secretion of the mosquito. So mosquitos belonging to the genus Anopheles are the vector of malaria.

CONTROL

The best way to control malaria is keeping the population of its vector under control, which is the primary weapon to control malarial infection. Use of excessive insecticides has led to appearance of resistant varieties of mosquito, and also environmental degradation.

1. ANTILARVAL MEASURES: not allowing water to accumulate in places, proper drainage system and filling and levelling of ditches.

2. CHEMICAL CONTROL: it includes A) application of kerosene, diesel, fuel oil, etc in stagnant water in a week.

3. Application of paris green (Copper acetoarsenite) in mosquito breeding places. It leads to stomach poisoning of larva leading to death.

4. BIOLOGICAL CONTROL: introduction of larvicidal fishes such as Gambusia and Lebistes, in breeding places is helpful.

5. ANTI-ADULT MEASURES: killing of adult mosquitoes by applying various insecticides.

6. PROTECTION AGAINST MOSQUITO BITES: use of mosquito nets, repellents etc.

Shelford Tutorials

LINE BY LINE EXPLANATION OF NCERT, CLASS 7 - SCIENCE, CHAPTER 1: NUTRITION IN PLANTS

Line by line explanation of OUR LIVING WORLD, Science book, CLASS 6: CHAPTER 2: FOOD: DAV GROUPS/SCHOOLS

ORDER HEMIPTERA

Blood Sucking Bugs (Order Hemiptera; Suborder Heteroptera)

DIGESTIVE SYSTEM: INTRODUCTION AND GENERAL PLAN OF ALIMENTARY CANAL

ORIGIN & EVOLUTION OF REPTILES

GENERAL INFO ON HAZARDS

General characters and classification of Siphonaptera

Determination of Lactose percentage in Milk sample (Benedict's Method)

FORMULA FOR CALCULATING CONCENTRATION OF PLANT EXTRACTS

Hello there!!!!i have prepared an excel sheet in Excel - 2007, which can be used to calculate the concentration of the plant extracts in mg/ml.

calculate concentration

to go to the excel sheet for downloading or calculating

GENERAL CHARACTERS OF RADIATA

Giardiasis: General Introduction

AMOEBIASIS: GENERAL INTRODUCTION

TYPHOID

REPRODUCTION IN ORGANISMS: AN OVERVIEW

Potable Water - Sources and Methods of Purification at Domestic level

BIOCHEMICAL TEST FOR PRESENCE OF CARBOHYDRATE (QUALITATIVE TEST)

Therapeutic efficacy of Cinnamomum tamala (Buch.-Ham.) and Aegle marmelos (L.) leaf

Sukumar Dandapat*, Manoj Kumar and M. P. Sinha

NATIONAL CONFERENCE ON HARMONY WITH NATURE IN CONTEXT OF ENVIRONMENTAL ISSUES AND CHALLENGES OF THE 21ST CENTURY (HARMONY - 2014)

Pharmacological Screening of Leaf Extract of Adhatoda vasica for Therapeutic Efficacy

Digestive System of Scoliodon

The Ecoscan: volume IV (special issue); 241-246

GROWTH INHIBITORY IMPACT OF ADHATODA VASICA AND VITEX NEGUNDO ON SOME HUMAN PATHOGENS

PLACENTA

VECTOR OF MALARIA (A GENERALIZED STUDY)

Hello there!!!!
i have prepared an excel sheet in Excel - 2007, which can be used to calculate the concentration of the plant extracts in mg/ml.