Medical MCQs for Everyone

The arachnoid villi responsible for cerebrospinal fluid absorption protrude mainly in the:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 11 Jul 2010 05:29:21 PDT

The arachnoid villi responsible for cerebrospinal fluid absorption protrude mainly in the:

A. Superior saggital sinus
B. Inferior saggital sinus
C. Straight sinus
D. Transverse sinus
Answer is A: Superior saggital sinus.

The arachnoid villi are projections of the arachnoid matter into the venous sinuses. These villi are most numerous in the superior saggital sinus.

CSF is produced in the brain by modified ependymal cells in the choroid plexus (approx. 50-70%), and the remainder is formed around blood vessels and along ventricular walls. It circulates from the lateral ventricles to the foramen of Monro, third ventricle, aqueduct of Sylvius, fourth ventricle, foramina of Magendie and Luschka; subarachnoid space over brain and spinal cord; reabsorption into venous sinus blood via arachnoid granulations.

An interesting poster with a summary of CSF is located here.

Following radical mastectomy in a patient with carcinoma breast, winged scapula is due to injury to the:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 11 Jul 2010 04:55:47 PDT

On examination following surgical removal of a firm nodular cancer swelling in the right breast and exploration of the right axilla, a patient is found to have a winged scapula. This occurred due to injury to the:

A. Subscapular muscle
B. Coracoid process of scapula
C. Long thoracic nerve
D. Circumflex scapular artery

Answer is C: Long Thoracic Nerve.

In the normal individual, the pull of the serratus anterior muscle keeps the medial border against the thoracic wall. However, when there is injury to the long thoracic nerve which supplies the serratus anterior muscle, there is winging of scapula, which is excessive prominence of the medial border of the scapula.

Actions of the serratus anterior muscle are:

It pulls the scapula forwards around the chest wall to protect the upper limb, as in pushing and punching actions
It rotates the scapula so that the glenoid cavity is turned upwards, which allows abduction of the arm above 90 degree.

In paralysis of the serratus anterior muscle, when movements like pushing, punching and raising arm above 90 degree is attempted, winging of scapula occurs.

Long Thoracic nerve is also known as “Nerve of Bell”.
Serratus anterior muscle arises by eight digitations from the upper eight ribs.

A 16-year-old disgruntled with failure attempts suicide by cutting her wrist. A superficial cut was noted on the wrist. All of the following structures have been damaged, EXCEPT:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 11 Jul 2010 04:26:45 PDT

A 16-year-old girl failed in her final examination. Disgusted with her life, she cut across the front of her wrist at the flexor retinaculum. She was rushed to the hospital. The surgeon noticed that the cut was superficial. All the following structures would have been damaged, EXCEPT:

A. Ulnar Nerve
B. Median Nerve
C. Palmar cutaneous branch of median nerve
D. Superficial branch of radial nerve

Answer is B: Median Nerve.

The median nerve lies deep to the flexor retinaculum. Except for the median nerve, all other options are superficial structures that could easily have been injured.

To be more precise, here is a list of structures in relation to the flexor retinaculum.

Structures passing superficial to flexor retinaculum

Ulnar vessels
Ulnar nerve
Palmar cutaneous branch of ulnar nerve
Palmar cutaneous branch of median nerve
Tendon of Palmaris longus

Structures passing deep to flexor retinaculum

Median nerve
Ulnar bursa
Radial bursa
Tendons of flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus, and flexor carpi radialis.

The Cells belonging to the following type of epithelium are provided with extra reserve of cell membrane:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 28 Feb 2010 09:42:39 PST

The Cells belonging to the following type of epithelium are provided with extra reserve of cell membrane:

A. Transitional
B. Stratified Squamous
C. Stratified Cuboidal
D. Stratified Columnar

Answer is A. Transitional

An extra reserve of cell membrane is required at sites that are subjected to stress and tension changes. A typical example of such a site is the wall of the urinary bladder which is covered with transitional epithelium.

Transitional Epithelium is a stratified tissue and has the property to cope with stretching and tension. Being stratified, it consists of several layers of cells of varying shape in the absence of stretching or tension. As tension increases, the epithelial sheet is expanded and the number of observable cell layers (the reserve) will decrease and cell shape will change from cuboid to squamous.

The ability of the transitional epithelium to stretch protects the distensible structures that it lines from tearing when stretched with great force.

The Cell Junctions allowing exchange of cytoplasmic molecules between two cells are called:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 28 Feb 2010 09:15:14 PST

The Cell Junctions allowing exchange of cytoplasmic molecules between two cells are called:

A. Gap Junctions
B. Tight Junctions
C. Anchoring Junctions
D. Focal Junctions

Answer is A. Gap Junctions.

Gap Junctions are a type of intercellular junction comprising a narrowed portion (about 3 nm) of the intercellular space, that contains channels or pores (2 nm) composed of hexagonal arrays of membrane spanning proteins around a central lumen (connexon) through which pass ions and small molecules such as most sugars, amino acids, nucleotides, vitamins, hormones and cyclic AMP.

Gap junctions were so named because of the "gap" shown to be present at these special junctions between two cells. One gap junction is composed of two connexons (or hemichannels) which connect across the intercellular space. It directly connects the cytoplasm of two cells, which allows various molecules and ions to pass freely between cells.

To come to a definite conclusion about this answer, let us review the different types of cell connections. There are 3 major forms of direct cell connections.

Desmosomes: Small 'spot-welds' that hold adjacent cells together. Fibres on the outer surface of each desmosome interlock with each other. Internally, they are anchored by fibres of the cytoskeleton.

Adjacent Skin Cells are typical examples of desmosome.

Gap Junctions: Formed when membrane channels of adjacent plasma membranes adhere to each other. These serve two effects:
- Form gaps or tunnels that join cytoplasm of two cells.
- Fuse the two plasma membranes into a single structure
Tight Junctions: Occur in cells that are joined by collars of tightly fused membranes. Molecules cannot penetrate or spread through cracks in between cells.

Example includes Lining of the intestine (the only way molecules can get past is through controlled channels or carrier molecules in plasma membrane).

Women receiving Oestrogen therapy have increased risk of developing all of the following cancers, EXCEPT:

noreply@blogger.com (Dr Lawrence Kindo) — Wed, 24 Feb 2010 08:44:10 PST

Women receiving Oestrogen therapy have increased risk of developing all of the following cancers, EXCEPT:

A. Breast Cancer
B. Endometrial Carcinoma
C. Carcinoma of gall bladder
D. Hepatocellular Carcinoma

Answer is C. Carcinoma of gall bladder.

Hepatocellular Carcinoma is a known consequence of long-term androgenic steroid administration, exposure to Thorium Dioxide and Vinyl Chloride, and possibly with exposure to Oestrogens in the form of oral contraceptives.

Oestrogens predispose the OCP consumer to hepatocellular carcinoma by causing hepatic adenomas. Hepatic adenomas are notoriously associated with malignant transformation in about 10% in 10 years among those exposed to oral contraceptives.

Definite Risks of Oestrogen Therapy
- Breast Cancer
- Endometrial Carcinoma
- Venous Thromboembolism
- Hepatocellular Carcinoma

Probable Risks associated with Oestrogen Use
- Gall Bladder disease (Gall Stones)
- Colorectal Cancer
- Ovarian Cancer
- Cognitive decline and dementia

The sensory supply of the palate is through all of the following, EXCEPT:

noreply@blogger.com (Dr Lawrence Kindo) — Wed, 10 Feb 2010 20:50:10 PST

The sensory supply of the palate is through all of the following, EXCEPT:

A. Facial Nerve
B. Hypoglossal Nerve
C. Glossopharyngeal Nerve
D. Maxillary division of Trigeminal Nerve

Answer is B. Hypoglossal Nerve

General sensory nerves of the palate:

Middle and Posterior (lesser) Palatine nerves, which are branches of Maxillary nerve through the Pterygopalatine ganglion.
From the Glossopharyngeal nerve

Special sensory (Gustatory) nerves:

Carrying taste sensations from the oral surface. Are contained in the Lesser Palatine nerves. The fibres travel through the Greater Petrosal nerve to the geniculate ganglion of the Facial nerve and from there to the nucleus of the solitary tract.

Hypoglossal Nerve: It supplies motor fibres to all of the muscles of the tongue, except the palatoglossus muscle which is innervated by the vagus nerve (cranial nerve X) or, according to some classifications, by fibers from the glossopharyngeal nerve (cranial nerve IX) that "hitchhike" within the vagus. Hence, it is the only one which is purely motor.

Which of the following muscles is supplied by mandibular nerve?

noreply@blogger.com (Dr Lawrence Kindo) — Wed, 10 Feb 2010 19:56:38 PST

Which of the following muscles is supplied by mandibular nerve?

A. Masseter
B. Buccinator
C. Tensor veli palati
D. Posterior belly of digastric

Answer is C. Tensor veli palati

Tensor veli palati is supplied by the mandibular nerve.

Masseter muscle is supplied by the masseteric nerve, a muscular branch of the mandibular nerve.
Buccinator is supplied by the facial nerve.
Tensor veli palati is supplied by the mandibular nerve directly. Hence, most appropriate answer.
Posterior belly of digastric is supplied by the facial nerve. Interestingly, the anterior belly of the same muscle is supplied by the mandibular nerve.

Points to REMEMBER:

Mandibular Nerve: Originates from Ist Arch. Supplies: Tensor tympani, Tensor veli palati, mylohyoid, Anterior belly of digastric, Muscles of mastication (Masseter, Temporalis, Medial and Lateral pterygoid).
Facial Nerve: Originates from IInd Arch. Supplies: Stapedius, Stylohyoid, Posterior belly of Digastric, Muscles of the face, Auricular muscles, Occipito frontalis (both bellies) and Platysma.
Glossopharyngeal Nerve: IIIrd Arch. Supplies: Only Stylopharyngeus
Superior Laryngeal Nerve and Recurrent Laryngeal Nerve: Originates from IVth and Vth Arches. Supplies: Muscles of Pharynx, Soft palate, Larynx

A patient with external haemorrhoids develops pain while passing stools. Nerve mediating this pain is:

noreply@blogger.com (Dr Lawrence Kindo) — Mon, 08 Feb 2010 10:59:39 PST

A patient with external haemorrhoids develops pain while passing stools. Nerve mediating this pain is:

A. Hypogastric nerve
B. Pudendal nerve
C. Splanchnic visceral nerve
D. Sympathetic plexus

Answer is B. Pudendal Nerve.

External haemorrhoids occur below the pectinate line and are very painful. This region is supplied by Inferior Rectal nerve (S2, S3, S4), a somatic nerve, which in turn is a branch of the pudendal nerve.

In contrast, the anal canal above the pectinate line is supplied by Sympathetic (Inferior Hypogastric plexus, L1 and L2) and Parasympathetic (Pelvic Splanchnic, S2, S3, S4) They carry pain fibres from the internal haemorrhoids.

All of the following are true regarding blood supply to the kidney, EXCEPT:

noreply@blogger.com (Dr Lawrence Kindo) — Mon, 08 Feb 2010 10:43:56 PST

All of the following are true regarding blood supply to the kidney, EXCEPT:

A.Stellate veins drain superficial zone
B. It is a type of portal-circulation
C. The renal artery divides into five segmental arteries before entering the hilum
D. Its segmental arteries are end-arteries

Answer is B. It is a type of portal-circulation.

Portal Circulation signifies circulation of blood from capillaries of one organ through larger vessels to capillaries of another organ before returning through larger veins to the heart. Examples include Liver and Hypophyseoportal.

In the Kidney, there are two capillary networks viz. glomerulus and vasarecta, but they occur in the same organ (kidney). Hence, it does not satisfy the criterion of portal circulation.
Each renal artery usually divides into 5 segmental arteries that enter the hilum of the kidney, 4 in front, and 1 behind the renal pelvis.
Segmental arteries are end arteries with little or no anastomosis.
Several stellate veins drain the most superficial zone of the renal cortex and converge beneath the fibrous renal capsule to drain several interlobular veins.

An interesting flash video on circulation of the kidney is here.

Ureteric constriction is seen at all the following positions, EXCEPT:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 17 Jan 2010 12:12:48 PST

Ureteric constriction is seen at all the following positions, EXCEPT:

A. Ureteropelvic junction
B. Ureterovesicle junction
C. Crossing of iliac artery
D. Ischial spine

Answer is D. Ischial spine

The normal ureter is not of uniform caliber, with three distinct narrowings classically described: the ureteropelvic junction, crossing of the iliac vessels, and the ureterovesical junction.

Sites of narrowing of the normal ureter are:

Ureteropelvic junction: At the ureteropelvic junction, the renal pelvis tapers into the proximal ureter. In many cases, this perceived narrowing may be more apparent than real, with no evidence of obstruction evident on radiographic or endoscopic investigation.
Crossing of the iliac vessels: Due to a combination of extrinsic compression of the ureter by the iliac vessels and the necessary anterior angulation of the ureter as it crosses the iliac vessels to enter into the pelvis. There is also no intrinsic change in the ureteral caliber at this location.
Ureterovesical junction: A true physical restriction of the ureter as it makes the intramural passage through the bladder wall to the ureteral orifice.
Juxtaposition of the vas deferens or broad ligament
Ureteric orifice

Diaphragmatic hernia can occur through all the following, EXCEPT:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 17 Jan 2010 11:46:20 PST

Diaphragmatic hernia can occur through all the following, EXCEPT:

A. Oesophageal opening
B. Costovertebral triangle
C. Costal and sternal attachment of the diaphragm
D. Inferior vena caval opening

Answer is D. Inferior vena caval opening

Inferior vena caval opening is situated at about 8th thoracic vertebra, transmits the vena cava and is not a site for diaphragmatic herniation.

Possible sites of diaphragmatic hernia are:

Oesophageal hiatus: Site of hiatus hernia, comprising 98% of all diaphragmatic hernias.
Sternocostal triangle: Lies between sternal and costal areas and transmits superior epigastric vessels and is a potential site for acquired herniation.
Lumbosacral triangle: Situated between costal and lumbar vertebral portions (costovertebral). Stomach and other peritoneal viscera herniate through it.

A quick review of the various openings of the diaphragm:

The superficial external pudendal artery is a branch of:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 17 Jan 2010 11:21:31 PST

The superficial external pudendal artery is a branch of:

A. Femoral artery
B. External iliac artery
C. Internal iliac artery
D. Aorta

Answer is A. Femoral Artery

The femoral artery is the principal supply to the anterior compartment of the thigh, as well as the rest of the lower limb. It gives off 3 superficial and 3 deep branches in the femoral triangle.

Superficial branches are:

Superficial external pudendal
Superficial epigastric
Superficial circumflex iliac

Deep branches are:

Profunda femoris: It is the largest branch of the femoral artery - also the chief artery to supply all 3 compartments of the thigh. Its branches are a) Medial circumflex femoral artery b) Lateral circumflex femoral artery, and c) Four perforating arteries
Deep external pudendal
Muscular branches

The weight of the upper limb is transmitted to the axial skeleton by:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 17 Jan 2010 11:01:52 PST

The weight of the upper limb is transmitted to the axial skeleton by:

A. Coracoclavicular ligament
B. Coracoacromial ligament
C. Costoclavicular ligament
D. Coracohumeral ligament

Answer is A. Coracoclavicular ligament.

The Coracoclavicular ligament is largely responsible for suspending the weight of the scapula and upper limb from the clavicle. This very strong ligament extends from the coracoid process to the under-surface of the clavicle as the name suggests.

Functions of the different ligaments at the shoulder joint are as follows:

Coracoclavicular ligament: Extends from coracoid process to the under-surface of the clavicle Action: Responsible for suspending the weight of the scapula and upper limb from the clavicle.
Coracoacromial ligament: Extends between coracoid process and acromion. Action: Protects superior aspect of the joint
Coracohumeral ligament: Extends from root of the coracoid process to greater tuberosity of humerus. Action: Strengthens the capsule above.
Costoclavicular ligament: Extends from junction of first rib with first costal cartilage to inferior surface of sternal end of clavicle.

Elastic cartilage is found in:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 17 Jan 2010 10:39:25 PST

Elastic cartilage is found in:

A. Auditory Tube
B. Nasal Septum
C. Articular Cartilage
D. Costal Cartilage

Answer is A. Auditory Tube

Elastic cartilage is found in the external ear, in the walls of the external auditory canal and auditory (Eustachean) tube and in the larynx.

Yellow elastic cartilage is found in:

External ear
External auditory canal
Auditory (Eustachean) tube
Corniculate cartilage
Epiglottis
Apices of arytenoids

Hyaline cartilage is found in:

Costal cartilage
Nasal cartilage
Some laryngeal
Tracheobronchial
All temporary and most articular cartilages

All of the following features are seen in neurons from dorsal root ganglia, EXCEPT:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 17 Jan 2010 10:22:51 PST

All of the following features are seen in neurons from dorsal root ganglia, EXCEPT:

A. They have centrally located nuclei
B. They are derived from neural crest cells
C. They are multipolar
D. They contain lipofuscin granules

Answer is C. They are multipolar

They have centrally located nuclei as in the picture

The dorsal root ganglia develops in the embryo from neural crest cells.
These neurons are of the pseudo-unipolar type, meaning they have an axon with two branches that act as a single axon, often referred to as a distal process and a proximal process.

Age-related accumulation of lipofuscin pigment in dorsal root ganglion has been noted and studied.

Which of the following is true regarding gastrulation:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 17 Jan 2010 09:45:17 PST

Which of the following is true regarding gastrulation:

A. Establishes all the three germ layers
B. Occurs at the caudal end of the embryo prior to its cephalic end
C. Involves the hypoblastic cells of the inner cell mass
D. Usually occurs at 4 weeks

Answer is A. Establishes all the three germ layers.

Gastrulation is the process that establishes all the 3 germ layers in the embryo.
Gastrulation is the most characteristic event occurring during the 3rd week and not the 4th week
The embryonic epiblast undergoes gastrulation. It does not involve the hypoblastic cells of the inner cell mass.
Occurs at the cephalic end prior to the caudal end.

Gastrulation of a diploblast: Formation of Germ Layers from (1) a blastula to (2) a gastrula.

Some of the ectoderm cells (orange) move inward forming the endoderm (red).

All of the following are derivatives of the neural crest, EXCEPT:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 17 Jan 2010 09:21:52 PST

All of the following are derivatives of the neural crest, EXCEPT:

A. Melanocyte
B. Adrenal Medulla
C. Sympathetic Ganglia
D. Cauda Equina

Answer is D. Cauda Equina

The following are structures derived from the neural crest:

Neurons:

Spinal posterior nerve root ganglia (dorsal root ganglia)

Sensory ganglia of the 5th, 7th, 8th, 9th and 10th cranial nerves
Sympathetic ganglia

Pia mater and Arachnoid mater: Not Dura mater
Schwann cells
Adrenal Medulla, Chromaffin tissue
Melanoblasts, mesenchyme of dental papilla

Hence, only Cauda Equina stands out among the options as not being a derivative of the neural crest.

More details about the neural crest is available at Developmental Biology by Scott F. Gilbert 6th Edition

A man with alcoholic liver failure requires general anaesthesia for surgery. Anaesthetic agent of choice is:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 06 Dec 2009 09:56:41 PST

A man with alcoholic liver failure requires general anaesthesia for surgery. Anaesthetic agent of choice is:

A. Ether
B. Halothane
C. Methoxyflurane
D. Isoflurane

Answer is D. Isoflurane

Chronic Alcoholism damages the liver and also induces enzymes involved in the metabolism of drugs. Hence, the response to drugs is not always predictable in a chronic alcoholic.

Ether, Halothane and Methoxyflurane are metabolised by the liver and hence would preferably be avoided in liver failure.

Perioperative considerations in hepatic failure:

Even in severe liver disease the problem is usually one of exaggerated effects of drugs on the CNS, rather than poor liver metabolism.
Hepatic blood flow is altered by anaesthetic drugs (including alpha and beta agonists/antagonists), positive pressure ventilation, PEEP, and surgical technique.
In most cases anaesthesia reduces hepatic blood flow, particularly if Halothane is used. However, Isoflurane may improve it.
Regional techniques may be used as long as coagulation is not deranged, and it should be remembered that all local anaesthetics are metabolised by the liver.
Isoflurane, Sevoflurane, or Desflurane are the preferred volatile agents as Enflurane, and particularly Halothane, have marked effects in decreasing hepatic blood flow and inhibiting drug metabolism.

The following anaesthetic drugs are considered safe in liver failure:

Premedication: Lorazepam. Midazolam and Diazepam can be used at a lower dose.
Induction: Propofol, Etomidate and Thiopental
Maintenance: Desflurane, Sevoflurane, Isoflurane, Nitrous Oxide. Enflurane may be used with caution. However, Halothane is contradicted because of the risk of hepatitis.
Muscle Relaxants: Atracurium, Cisatracurium. Pancuronium, Vecuronium and Suxamethonium may be used with caution.
Opioids: Remifentanil. Drugs that can be used with a reduced dosage are Fentanyl, Alfentanil, Morphine, and Pethidine.
Analgesics: Paracetamol. NSAIDS, Lidocaine and Bupivacaine may be used with caution.

A powerpoint presentation on the said topic can be viewed at the following link:

Anaesthesia for patients with liver disease

Anaesthetic agent of choice in renal failure is:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 06 Dec 2009 09:55:59 PST

Anaesthetic agent of choice in renal failure is:

A. Methoxyflurane
B. Isoflurane
C. Enflurane
D. None

Answer is B. Isoflurane

The elimination of volatile anaesthetic agents is not dependent on renal function and their activity is unaffected by CRF. The hepatic metabolism of both enflurane and sevoflurane will theoretically produce nephrotoxic fluoride ions and their use should be discouraged for prolonged durations. Metabolism of halothane produces fluoride ions when the liver is hypoxic but has been used safely in patients with renal disease. It has a greater myocardial depressant effect and causes more arrhythmias than other inhalational agents and caution should be observed when used in CRF patients with cardiovascular impairment.

Isoflurane, although more expensive, may be the agent of choice as it undergoes less metabolism to fluoride ions. Nitrous oxide has little effect on the kidney. Older agents such as cyclopropane, ether and tricloroethylene are not recommended as they cause renal vasoconstriction.

Methoxyflurane is highly nephrotoxic
Enflurane is best avoided as the nephrotoxic levels of fluoride ions are seen just after 3.5 MAC hours
Isoflurane, Sevoflurane and Halothane result in little or no increase in fluoride ions and are preferred.

All of the following agents can be given for induction of anaesthesia in children except:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 06 Dec 2009 10:01:38 PST

All of the following agents can be given for induction of anaesthesia in children except:

A. Halothane
B. Sevoflurane
C. Morphine
D. Nitrous Oxide

Answer is C. Morphine

Morphine should not be used in infants specially those less than 6 months of age.

According to "A Practice of Anaesthesia for Infants and Children", neonates are more sensitive to the respiratory depressant effects of Morphine, and it is rarely used to premedicate that age group. It also cites its use as a premedication and not as an inducing agent. Lee also states that morphine is also not commonly recommended in older children (3-10 years of age).

Most commonly used method for inducing gaseous anaesthesia in children is with Oxygen, with or without Nitrous Oxide and either Halothane or Sevoflurane.

Halothane is well tolerated in children and the risk of halothane-induced hepatitis on repeated administration is small.

Enflurane and Isoflurane are more pungent and not recommended

Sevoflurane, if available is the agent of choice

Nitrous Oxide is particularly useful because of the speed of induction, absence of cardiovascular and respiratory depression, its rapid onset and offset, and its powerful analgesic action.

Bilirubin is secreted by:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 06 Dec 2009 10:02:29 PST

Bilirubin is secreted by:

A. Bile salts
B. Bile pigment
C. Secretin
D. CCK

Answer is A. Bile salts

Bilirubin is the main bile pigment that is formed from the breakdown of heme in red blood cells. The broken down heme travels to the liver, where it is secreted into the bile by the liver.

The following is a review of the normal pathway for bilirubin production and excretion and its relationship to laboratory assessment of liver function:

Step 1: Red blood cells are broken down by the reticuloendothelial system and unconjugated bilirubin in the bloodstream is carried by albumin to the liver. This is known as "pre-hepatic," "free," "unconjugated," or"indirect bilirubin" (normal value = 0.1 - 1.0 mg/dl)

Step 2: The liver converts or conjugates bilirubin and makes it water-soluble. This is known as "posthepatic", "conjugated" or "direct" bilirubin (normal value = 0.0 - 0.4 mg/dl)

Step 3: Conjugated bilirubin is excreted via bile salts to intestine. Bacteria in the intestine break down bilirubin to urobilinogen for excretion in the feces (normal value for fecal urobilinogen = 40 - 280 mg/day).

This is a trick question or inappropriately worded. Caution must be practised in answering such a question. An appropriate correction would be : Bilirubin is secreted 'via' and not 'by'.

Most important stimulant for bile secretion is:

noreply@blogger.com (Dr Lawrence Kindo) — Wed, 18 Nov 2009 23:48:02 PST

Most important stimulant for bile secretion is:

A. Cholecystokinin
B. Secretin
C. Bile acid
D. Bile salts

Answer is D. Bile Salts

Choleretics are substances that increase the volume of secretion of bile from the liver as well as the amount of solids secreted.

Bile salts are amongst the most important physiological choleretics. Investigators have recognized the importance of bile salts in stimulating biliary secretion by the liver.

Gall bladder contraction is stimulated by:

noreply@blogger.com (Dr Lawrence Kindo) — Sun, 06 Dec 2009 10:03:39 PST

Gall bladder contraction is stimulated by:

A. Gastrin
B. Secretin
C. Vagus
D. Cholecystokinin

Answer is D. Cholecystokinin

Presence of fat in the duodenum prompts secretion of CCK-PZ from the cells of the upper small intestine. CCK-PZ so released, causes contraction of the gall bladder and release of bile.

The literal meaning of the word cholecystokinin is a straightforward clue to the answer. From Greek - "chole" - bile, "cysto" - sac and "kinin" - move, which is "move the bile sac".

CCK-PZ causes all of the following, except:

noreply@blogger.com (Dr Lawrence Kindo) — Wed, 18 Nov 2009 23:09:55 PST

CCK-PZ causes all of the following, except:

A. Gall bladder contraction
B. Pancreatic enzyme secretion
C. Increased gastrin secretion
D. Decreased lower oesophageal sphincter contraction.

Answer is C. Increased gastrin secretion.

Cholecystokinin (CCK-PZ) earlier called pancreozymin, is a peptide hormone of the gastrointestinal system responsible for the digestion of fat and protein. The literal meaning of the word cholecystokinin from its Greek origin is 'move the bile sac'.

Synthesized by the I-cells in the mucosal epithelium of the small intestine and is secreted in the duodenum.
It causes gall bladder contraction releasing bile from the gall bladder and hence obviates the first option.
It also causes release of digestive enzymes from the pancreas obviating the second option.
Its recent use as a hunger suppressant in Western countries is well-known.
Cholecystokinin inhibits the secretion of gastrin from antral G cells, an effect that is speculated to be mediated by D cells secreting somatostatin. Hence, there should be decreased gastrin secretion.
CCK also causes relaxation of the lower oesophageal sphincter by reducing its tone.