Pre Clinical Medical Science SBAs
Pre Clin Digestive: (62 questions)

Questions

• 1
  Which organ in the epigastrum is entirely retroperitoneal?
  Difficulty: Easy     Topic: Retroperitoneal organs
  a

  Duodenum

  b

  Liver

  c

  Pancreas

  d

  Spleen

  e

  Stomach
  Explanation: The organs that are entirely retroperitoneal are: pancreas, kidneys, ascending and descending colon, rectum and the aorta. Most of the 1st part of the duodenum is not retroperitoneal but the remainder is.
• 2
  What does a raised gamma-glutamyl transferase and raise alkaline phosphatase suggest?
  Difficulty: Easy     Topic: ALP and GGT
  a

  Bile duct damage

  b

  Bone damage

  c

  Cardiac damage

  d

  Hepatocellular damage

  e

  Placental damage
  Explanation: Alkaline phosphatase (ALP) is an enzyme present in bone, placenta and biliary epithelium as different isozymes. It can be raised due to damage to any of these tissues. However gamma-glutamyl transferase (GGT) is specific to the biliary tree so if both are high then it suggests an obstruction to the flow of bile or biliary injury.
• 3
  How is bilirubin metabolised inside hepatocytes?
  Difficulty: Easy     Topic: Bilirubin
  a

  Conjugated with gluruonic acid

  b

  Conjugated with sulphate

  c

  Exported straight into canaliculi

  d

  Hydrolysed by CYP450 enzymes

  e

  Hydroxylated by CYP450 enzymes
  Explanation: In hepatocytes bilirubin is conjugated with glucuronic acid by bilirubin-UDP-glucuronyl-transferase. This increases it's water solubility before it is exported into bile canaliculi. The CYP450 system enzymes do not normally act on bilirubin.
• 4
  What is urobilinogen?
  Difficulty: Easy     Topic: Urobilinogen
  a

  Bilirubin binding protein

  b

  Final product of intestinal modification of bilirubin

  c

  Lipid-soluble bilirubin metabolite

  d

  Precursor to bilirubin

  e

  Water-soluble bilirubin metabolite
  Explanation: Urobilinogen is formed in the intestine from the action of bacterial enzymes on conjugated bilirubin. It is a water-soluble metabolite of bilirubin and some is reabsorbed back into the blood, then excreted in the urine. The remainder stays in the bowel and is converted to stercobilinogen, which is brown and the final bilirubin metabolite.
• 5
  What liver function tests would be expected in a case of jaundice from Gilbert syndrome?
  Difficulty: Easy     Topic: Gilbert syndrome
  a

  Normal bilirubin and high ALT

  b

  Raised conjugated bilirubin, high ALT and high ALP

  c

  Raised conjugated bilirubin and high ALP

  d

  Raised unconjugated bilirubin and high ALT

  e

  Raised unconjugated bilirubin only
  Explanation: Gilbert syndrome is a condition caused by reduced activity in the bilirubin conjugation enzyme (UGT) during times of illness or stress. The effect is an inability to conjugate bilirubin causing raise unconjugated bilirubin but there is no damage to hepatocytes or biliary epithelium so ALT and ALP are normal.
• 6
  Which hepatitis virus only ever causes chronic inflammation, not acute?
  Difficulty: Medium     Topic: Hepatitis viruses
  a

  A

  b

  B

  c

  C

  d

  D

  e

  E
  Explanation: Hepatitis C virus is transmitted via blood and only causes chronic hepatitis but a high percentage of all those infected develop cirrhosis. Hepatitis A & E only cause acute illness and are transmitted faeco-orally. Hepatitis B (and D) can cause acute or chronic illness and may be transmitted via blood or sexually.
• 7
  Which condition causes cirrhosis and early onset emphysema without a smoking history?
  Difficulty: Easy     Topic: Uncommon liver diseases
  a

  Alpha-1-antitrypsin deficiency

  b

  Haemochromatosis

  c

  Primary biliary cirrhosis (PBC)

  d

  Primary sclerosing cholangitis (PSC)

  e

  Wilson disease
  Explanation: Alpha-1-antitrypsin is an enzyme that inactivates neutrophil proteases. Patients who are deficient develop emphysema due to protease damage in the lungs and cirrhosis due to accumulation of the abnormal protein. Haemochromatosis is the state of iron overload. PBC and PSC are biliary disease that may cause cirrhosis. Wilson disease is a condition of copper overload.
• 8
  Why do oesophageal varices develop in patients with cirrhosis?
  Difficulty: Easy     Topic: Oesophageal varices
  a

  Impaired coagulation

  b

  Low platelets

  c

  Pressure secondary to ascites

  d

  Raised portal vein pressure

  e

  Reduced venous fibrous tissue
  Explanation: Oesophageal varices are a manifestation of portal hypertension. Cirrhosis causes interruption to portal blood flow into the liver, causing a build up of pressure. Anastamoses between the portal and venous circulation open, which include veins at the base of the oesophagus that dilate to form varices. Coagulopathy and low platelets increase bleeding but don't cause varices. Ascites may increase risk of hernia due to pressure. Reduced venous fibrous tissue causes varicose veins.
• 9
  Where might a gallstone be impacted to cause cholecystitis but not jaundice?
  Difficulty: Easy     Topic: Gall stones
  a

  Ampulla of Vater

  b

  Common bile duct

  c

  Common hepatic duct

  d

  Cystic duct

  e

  Sphincter of Oddi
  Explanation: Gallstones may leave the gall bladder and impact in the ducts to cause obstruction of bile flow. Cholecystitis occurs when there is obstruction to outflow of the gall bladder. Jaundice occurs when there is obstruction to the outflow of bile. A stone in the cystic duct does not affect bile flow out the liver but does cause obstruction to the gall bladder.
• 10
  How does hepcidin function?
  Difficulty: Easy     Topic: Hepcidin
  a

  Increases ferritin release from hepatocytes

  b

  Increases iron uptake into enterocytes

  c

  Increases transferrin production by hepatocytes

  d

  Reduces ferritin uptake by hepatocytes

  e

  Reduces iron release from enterocytes
  Explanation: Hepcidin acts to reduce serum iron levels by preventing the efflux of iron from enterocytes. It binds to ferroportin, the channel that allows iron to exit enterocytes, and causes its degradation. When enterocytes are shed into the bowel lumen iron is lost with it. Hepcidin does not control secretion of transferrin or ferritin.
• 11
  What hormone or transmitter reduces the secretion of gastric acid by parietal cells?
  Difficulty: Medium     Topic: Gastric acid production
  a

  Acetylcholine

  b

  Gastrin

  c

  Ghrelin

  d

  Histamine

  e

  Secretin
  Explanation: Gastric acid is released by parietal cells in constitutively but this is increased in response to stimulation by: the vagus (releasing ACh), ECL cells (releasing histamine) or G-cells (releasing gastrin). Secretin is made by S-cells in the duodenum in response to low pH. It reduces gastrin release to cause a fall in acid secretion. Ghrelin is released by the stomach to stimulate hunger, not acid production.
• 12
  Where does Stensen’s duct open?
  Difficulty: Medium     Topic: Stensen's duct
  a

  Adjacent to the lingual frenulum

  b

  In the 2nd part of the duodenum

  c

  In the posterior nasopharynx

  d

  In the terminal ileum

  e

  Opposite the 2nd upper molar
  Explanation: Stensen's duct (or the parotid duct) passes from the parotid gland, through buccinator and buccal fat into the oral cavity, opening opposite the 2nd molar. The sublingual and submandibular glands open lateral to the lingual frenulum underneath the tongue. The Eustachian tube ends in the nasopharynx.
• 13
  Which cranial nerve supplies taste function to the anterior 2/3rd of the tongue?
  Difficulty: Easy     Topic: Tongue innervation
  a

  Facial

  b

  Glossopharyngeal

  c

  Hypoglossal

  d

  Trigeminal

  e

  Vagus
  Explanation: The chorda tympani branch of the facial nerve (CN VII) supplies taste to the anterior 2/3. General sensation is provided by the lingual nerve, a branch of trigeminal (CN V). For the posterior 1/3 of the tongue (past the sulcus terminalis) both taste and general sensation are supplied by the glossopharyngeal nerve (CN IX).
• 14
  Which salivary gland produces the most watery saliva?
  Difficulty: Hard     Topic: Salivary glands
  a

  Accessory glands

  b

  Parotid gland

  c

  Sublingual gland

  d

  Submandibular gland

  e

  Submental gland
  Explanation: The salivary glands produce slightly different compositions of saliva. The parotid produces the most watery secretion and the sublingual produces the most mucoid with the submandibular producing a mixed secretion. There is not a large submental salivary gland; it would be considered one of the accessory glands.
• 15
  Where does the oesophageal hiatus of the diaphragm lie?
  Difficulty: Easy     Topic: Diaphragmatic hiatuses
  a

  Anterior and inferior to the aortic hiatus

  b

  Anterior and inferior to the IVC hiatus

  c

  Anterior and superior to the aortic hiatus

  d

  Posterior and inferior to the aortic hiatus

  e

  Posterior and superior to the IVC hiatus
  Explanation: There are 3 main hiatuses in the diaphragm, the IVC, oesophagus and aorta. The oesophagus pierces the diaphragm at the level of T10 with the Vagus nerve. It is anterior to the aortic hiatus, which is also inferior at T12. The oesophageal hiatus is posterior to the IVC, which passes through at T8.
• 16
  What is abdominal mesentery?
  Difficulty: Easy     Topic: Mesentery
  a

  Connective tissue holding abdominal organs in place

  b

  Double-layered epithelium attaching small bowel to the posterior wall

  c

  Fat-laden connective tissue attached to the large bowel

  d

  Single-layer epithelium covering the abdominal viscera

  e

  Single-layer epithelium covering the anterior wall of the abdominal cavity
  Explanation: Mesentery is double-layered peritoneum that attaches the small bowel to the posterior abdominal wall at the level of L2. Contains blood vessels, nerves and lymphatics supplying the bowel. There are ligaments that hold organs in position e.g. right cardiac ligament attached to the liver. The omentum is connective tissue that attaches to the large bowel. The peritoneum is a single-layered epithelium: parietal lining the anterior abdominal wall and visceral covering the organs.
• 17
  What enzyme has the greatest role in promoting synthesis of glycogen?
  Difficulty: Easy     Topic: Glycogenesis
  a

  Adrenaline

  b

  Cortisol

  c

  Glucagon

  d

  Growth hormone

  e

  Insulin
  Explanation: Insulin is the body's main anabolic hormone - it promotes glycogen synthesis by activation of glycogen synthetase through a tyrosine kinase pathway. All the other 4 hormones listed are catabolic; the promote glycogenolysis and raise serum glucose levels.
• 18
  Within which structure does the epiploic foramen lie?
  Difficulty: Easy     Topic: Epiploic foramen
  a

  Gastro-hepatic ligament

  b

  Gastro-splenic ligament

  c

  Greater omentum

  d

  Mesentery

  e

  Transverse mesocolon
  Explanation: The epiploic foramen (foramen of Winslow) is part of the abdomen where is communication between the greater and lesser peritoneal sacs. It is located in the gastro-hepatic ligament, which forms part of the lesser omentum.
• 19
  Which structures define the anterior and posterior borders of the Pouch of Douglas?
  Difficulty: Easy     Topic: Pouch of Douglas
  a

  Anterior abdominal wall - bladder

  b

  Anterior abdominal wall - uterus

  c

  Bladder - rectum

  d

  Bladder - uterus

  e

  Uterus - rectum
  Explanation: The Pouch of Douglas s also known as the recto-uterine pouch. It is the most inferior point in the abdominal cavity in women. The equivalent area in men would be the recto-vesical pouch.
• 20
  What name is given to the outpouchings of fat on the serosa of large bowel?
  Difficulty: Easy     Topic: Large bowel
  a

  Appendices epiplocae

  b

  Brunner's glands

  c

  Haustrae

  d

  Plicae circulares

  e

  Taeniae coli
  Explanation: Appendices epiplocae are small pouches of fat present on the surface of large bowel. They are one of the 3 macroscopic features of large bowel, the other two are haustrae (partial folds in the bowel) and taeniae coli (longitudinal bands of muscle on the surface of the bowel). Plicae circulares (or valvuliae conniventes) are complete folds of the bowel in small intestine. Brunner's glands are alkaline secreting structures only in the duodenum.
• 21
  Where is McBurney’s point found?
  Difficulty: Easy     Topic: Appendix anatomy
  a

  At the duodeno-jejunal junction

  b

  1/3 from right anterior superior iliac spine to umbilicus

  c

  1/3 from the right mid-inguinal point to the umbilicus

  d

  1/3 from the umbilicus to the mid-point of the right inguinal ligament

  e

  1/3 from umbilicus to right anterior superior iliac spine
  Explanation: McBurney's point is the approximate surface anatomical location of the appendix. It is 1/3rd along a straight line from the right anterior superior iliac spine to the umbilicus. However the appendix can have a varied position, which gives a variety of clinical presentations of appendicitis. None of the other points described have significance.
• 22
  Where is the embryological division of the midgut and hindgut?
  Difficulty: Easy     Topic: Gut embryology
  a

  Duodenal-jejunal junction

  b

  Ileo-caecal valve

  c

  1/3rd transverse colon

  d

  2/3rd transverse colon

  e

  1/3rd distal colon
  Explanation: Embryologically the gut was divided into foregut, midgut and hindgut; this is mirrored in adult anatomy such that each section has a different blood supply, drainage and innervation. The foregut runs from upper oesophagus to the level of the ampulla of Vater. The midgut is from here to 2/3rd along the transverse colon, distal to this is hindgut.
• 23
  What is the dentate line?
  Difficulty: Easy     Topic: Dentate line
  a

  Division of foregut and midgut

  b

  Midpoint between pubic symphysis and thoracic inlet

  c

  Surface anatomical location of appendix

  d

  Where epithelium changes from simple columnar to stratified squamous in rectum

  e

  Where inferior epigastric vessels pierce abdominus rectus
  Explanation: The dentate line marks the division between endodermal-derived and ectodermal-derived epithelium in the rectum therefore at this point the epithelium changes from simple columnar to stratified squamous. The foregut-midgut division is at the level of ampulla of Vater. The transpyloric plane is at the midpoint symphysis and thoracic inlet. McBurney's point describes the appendix position. The inferior epigastric vessels pierce abdominus rectus at the arcuate line.
• 24
  What vessel supplies blood to the descending colon?
  Difficulty: Easy     Topic: Colon blood supply
  a

  Coeliac trunk

  b

  Inferior mesenteric artery

  c

  Internal iliac artery

  d

  Medical sacral artery

  e

  Superior mesenteric artery
  Explanation: Blood supply to the GIT is determined by embryological origin. Foregut is supplied by the coeliac trunk, the midgut is supplied by the superior mesenteric artery and the hindgut by the inferior mesenteric artery. The whole descending colon is a hindgut structure therefore its blood supply arises at the IMA. The IMA divides into left colic, sigmoid and superior rectal arteries - these feed into the marginal artery of Drummond that give off vasa recta to supply the colon.
• 25
  What vessel supplies blood to the descending colon?
  Difficulty: Easy     Topic: Colon blood supply
  a

  Coeliac trunk

  b

  Inferior mesenteric artery

  c

  Internal iliac artery

  d

  Medical sacral artery

  e

  Superior mesenteric artery
  Explanation: Blood supply to the GIT is determined by embryological origin. Foregut is supplied by the coeliac trunk, the midgut is supplied by the superior mesenteric artery and the hindgut by the inferior mesenteric artery. The whole descending colon is a hindgut structure therefore its blood supply arises at the IMA. The IMA divides into left colic, sigmoid and superior rectal arteries - these feed into the marginal artery of Drummond that give off vasa recta to supply the colon.
• 26
  Which muscle external to the bowel contributes most to the external anal sphincter?
  Difficulty: Medium     Topic: External anal sphincter
  a

  Bulbospongiosus

  b

  Iliacus

  c

  Obturator internus

  d

  Psoas minor

  e

  Puborectalis
  Explanation: Puborectalis passes from the pubic symphysis and loops around the rectum at the level of the external sphincter. When contracted, puborectalis causes a kink in the rectum that helps maintain continence. Some fibres of puborectalis and the external anal sphincter merge, both being striated muscle, and they contract simultaneously.
• 27
  Where does the ligamentum teres hepatis lie?
  Difficulty: Easy     Topic: Ligamentum teres hepatis
  a

  At the superior right edge of the liver

  b

  Between the gall bladder and the liver

  c

  Between the liver and the stomach

  d

  Between the umbilical vein remnant and the hepatic vein

  e

  Separating the right and left lobes of the liver
  Explanation: The ligamentum teres hepatis is a remnant of the venous channel between the liver and IVC that ran from the umbilical vein to the hepatic vein/IVC in the neonate. It passes through the adult liver, in the base of the falciform ligament (that separates the two liver lobes). The right coronary ligament is at the superior right of the liver. The gastro-hepatic ligament is between the stomach and liver. The gall bladder is attached via natural adhesions
• 28
  Where is the porta hepatis found?
  Difficulty: Easy     Topic: Porta hepatis
  a

  Inferior to the caudate lobe

  b

  Inferior to the cystic duct

  c

  Lateral to the IVC

  d

  On the anterior of the right lobe

  e

  Posterior to the pancreatic head
  Explanation: The porta hepatis is the point where the hepatic vein and common hepatic duct exit the liver; and the hepatic artery and portal vein enter. It is on the posterior aspect, between the right and left lobes, inferior to the caudate lobe and superior to the quadrate lobe. It is just medial to the IVC and superior to the cystic duct which branches off the common hepatic duct after it exits the porta hepatis.
• 29
  Which vessel lies immediately posterior to the superior of the right lobe of the liver?
  Difficulty: Easy     Topic: Liver relations
  a

  Hepatic vein

  b

  Inferior vena cava

  c

  Portal vein

  d

  Splenic vein

  e

  Superior mesenteric vein
  Explanation: The inferior vena cava lies immediately posterior to the right lobe of the liver before it passes into the thorax. The hepatic vein is short and joins the IVC near the porta hepatis. The portal vein descends away from the porta hepatis; it originates posterior to the head of the pancreas where it is formed by the union of the splenic vein and the superior mesenteric vein.
• 30
  Which organ immediately anterior to the body of the pancreas?
  Difficulty: Easy     Topic: Pancreatic relations
  a

  Duodenum

  b

  Liver

  c

  Spleen

  d

  Stomach

  e

  Transverse colon
  Explanation: The pancreas has a head, neck, body and tail. The duodenum wraps around the head of the pancreas. The neck and body are immediately underneath the stomach (pylorus and antrum) with the pancreatic tail projecting up towards the splenic hilum. The liver and transverse colon are both anterior to the stomach.
• 31
  What structures define the borders of Calot’s triangle?
  Difficulty: Hard     Topic: Calot's triangle
  a

  Common hepatic duct, right hepatic artery and cystic duct

  b

  Cystic duct, cystic artery and common hepatic duct

  c

  Inferior liver edge, cystic artery and right hepatic artery

  d

  Inferior liver edge, cystic duct and common hepatic duct

  e

  Right hepatic duct, cystic duct and common bile duct
  Explanation: Calot's triangle describes the important anatomical structures around the gall bladder with the aim of identifying where the cystic artery branches off the right hepatic artery, which should lie within the triangle. The superior border is the inferior edge of the right liver lobe, the inferior border is the cystic duct and the medial border is the common hepatic duct.
• 32
  What is segmentation?
  Difficulty: Easy     Topic: Segmentation
  a

  Complex gastric muscle contraction for mixing

  b

  Large colonic contraction for propulsion

  c

  Sequential contraction of circular smooth muscle for propulsion

  d

  Simultaneous circular muscle contraction for mixing

  e

  Sphincter relaxation to allow propulsion
  Explanation: Segmentation is method of mixing used in the intestine where several rings of circular muscle contract at one time. This is in contrast to peristalsis that requires sequential circular muscle contraction for propulsion. Churning is a complex method of gastric mixing. Large colonic contraction is called mass peristalsis. Sphincter relaxation is a separate process caused by parasympathetic activation..
• 33
  What electrolyte movement is performed by salivary ductular cells?
  Difficulty: Easy     Topic: Salivary glands 2
  a

  HCO3- and Na+ reabsorption

  b

  HCO3- and Na+ secretion

  c

  HCO3- reabsorption and Na+ secretion

  d

  HCO3- secretion and Na+ reabsorption

  e

  K+ reabsorption
  Explanation: Ductular cells produce the alkaline content of saliva by secreting HCO3-. They also reabsorb sodium and secrete potassium which increases the viscosity of saliva.
• 34
  How does parasympathetic stimulation influence salivary gland secretion?
  Difficulty: Medium     Topic: Salivary glands 3
  a

  Increases HCO3- content

  b

  Increases saliva viscosity

  c

  Increases volume of watery saliva

  d

  No effect of enzyme secretion

  e

  Reduces mucus production
  Explanation: Parasympathetic stimulation increases the rate of production of the primary secretion, which has a composition similar to plasma, as well as increasing enzyme production. It has little effect on ductular modification so there is a greater increase in volume without any rise in alkalinity. Mucus production slightly rises.
• 35
  What is the main consequence of chronic vitamin A deficiency?
  Difficulty: Hard     Topic: Vitamin A
  a

  Blindness

  b

  Coagulopathy

  c

  Jaundice

  d

  Neuropathy

  e

  Osteomalacia
  Explanation: Vitamin A (retinoic acid) is crucial for retinal function and the cornea - consequently deficiency results in blindness. Vit K deficiency causes coagulopathy due to lack of clotting factors. Vit A excess causes jaundice. Vit E or B12 deficiency causes neuropathy. Osteomalacia is caused by vitamin D deficiency.
• 36
  Which of the following is NOT a fat-soluble vitamin?
  Difficulty: Easy     Topic: Fat soluble vitamins
  a

  A

  b

  C

  c

  D

  d

  E

  e

  K
  Explanation: The fat soluble vitamins as A, D, E and K. Vitamin C is needed for normal function of the clotting system, connective tissues and other metabolic processes but is not fat soluble.
• 37
  Which hormone causes increased pancreatic enzyme secretion and gall bladder contraction?
  Difficulty: Easy     Topic: Gall bladder contraction
  a

  Cholecystokinin

  b

  Gastrin

  c

  Lipase

  d

  Secretin

  e

  Somatostatin
  Explanation: Cholecystokinin is released by I-cells of the duodenum is the presence of lipid. It acts on the pancreas to increase the rate of secretion of enzymes, including lipase, and stimulates gall bladder contraction. Gastrin and secretin are involved in regulating gastric acid production. Somatostatin has a variety of roles in the GIT.
• 38
  What is the role of pancreatic lipase?
  Difficulty: Easy     Topic: Lipase
  a

  Allow binding of co-lipase

  b

  Cleave TAG in micelles

  c

  Emulsify fat

  d

  Facilitate micelle formation

  e

  Facilitate VLDL formation
  Explanation: Pancreatic lipase acts on triacylglycerides (TAG) to produce monoacylglycerides and free fatty acids. It requires the presence of co-lipase to bind. The TAG is found in micelles, which require bile salts to form. VLDL are formed in the liver.
• 39
  In what form is fat exported from enterocytes?
  Difficulty: Easy     Topic: Lipid handling 1
  a

  Chylomicrons

  b

  Free fatty acids

  c

  LDL

  d

  Micelles

  e

  VLDL
  Explanation: Free fatty acids and monoacylglycerides diffuse into enterocytes and pass into the smooth endoplasmic reticulum. They bind proteins and are re-formed into TAG before being exported as large chylomicron molecules. VLDL are made by the liver, LDL are the breakdown product of VLDL. Micelles are formed in the bowel prior to absorption.
• 40
  How are VLDL metabolised once released into circulation?
  Difficulty: Easy     Topic: Lipid handling 2
  a

  Bind HDL and pass to liver

  b

  Free fatty acids are cleaved by LPL

  c

  Pass directly to the liver

  d

  Receive cholesterol from muscle

  e

  Receive TAG from adipose
  Explanation: During the fasting state the liver produces VLDL as an energy source for peripheral tissues. Lipoprotein lipase acts on TAG within VLDL to release free fatty acids for muscle and other tissues; this process converts VLDL into LDL. HDL bind LDL and direct both molecules back to the liver.
• 41
  What is the role of HDL?
  Difficulty: Easy     Topic: Lipid handling 3
  a

  Accept free fatty acids from adipose

  b

  Accept TAG from liver

  c

  Bind LDL and pass to liver

  d

  Increase circulating VLDL

  e

  Supply TAG to muscle
  Explanation: HDL is formed from normal cell turnover and their production of cholesterol. HDL binds circulating LDL and then transports both molecules to the liver for uptake and re-processing. In this way, HDL helps to reduce circulating levels of LDL - HDL is thought to be beneficial in reducing atherosclerosis.
• 42
  Through which intracellular pathway does parasympathetic stimulation cause an increase in pancreatic acinar secretions?
  Difficulty: Hard     Topic: Parasympathetic stimulation
  a

  ATP-sensitive K+ channels

  b

  cAMP-PKA

  c

  cGMP-PKA

  d

  Phospholipase A2-arachidonic acid

  e

  PIP2-phospholipase C
  Explanation: Post-ganglionic parasympathetic neurones release ACh that binds muscarinic acetylcholine receptors. These are G-protein coupled receptors that cause activation of the phosphatidylinositol-bisphosphate pathway with resultant activation of protein kinase C and a rise in intracellular calcium. The increase in calcium causes exocytosis of granules containing zymogens.
• 43
  Which reflex has the largest role in stimulating pancreatic secretions?
  Difficulty: Easy     Topic: Pancreatic reflexes
  a

  Cephalo-pancreatic

  b

  Colo-pancreatic

  c

  Gastro-pancreatic

  d

  Intestino-pancreatic

  e

  Pancreato-pancreatic
  Explanation: There are 3 reflexes that stimulate pancreatic secretions, in addition to a basal level of constitutional secretion. Cephalo-pancreatic has the smallest role and is activated by food in the mouth. Gastro-pancreatic is activated by stomach distension and release of gastrin. Intestino-pancreatic has the dominant role and involves: CCK and secretin release from the duodenum, and vagal stimulation secondary to duodenal distension.
• 44
  How is pancreatic trypsinogen activated?
  Difficulty: Easy     Topic: Trypsinogen
  a

  By alkaline duodenal secretion

  b

  By brush border enterokinase

  c

  By gastric acid

  d

  By gastric pepsin

  e

  Following activation of chymotrypsin
  Explanation: All pancreatic enzymes are secreted as inactive zymogens. Trypsinogen is the first to be activated. It comes into contact with enterokinase, an enzyme present on the brush border of duodenal enterocytes, which converts trypsinogen to trypsin. Trypsin then goes on to activate the other pancreatic enzymes. pH has a role in regulating activity but doesn't activate trypsinogen.
• 45
  How are gallstones thought to cause acute pancreatitis?
  Difficulty: Medium     Topic: Pancreatitis 1
  a

  Cause intrapancreatic activation of zymogens

  b

  Cause reflux of enterokinase

  c

  Inhibit acinar cell secretion

  d

  Physical disruption of pancreatic tissue

  e

  Secondary to obstructive jaundice
  Explanation: Gallstones are the most common cause of acute pancreatitis in the UK. When they obstruct the flow of bile there is stagnation of pancreatic zymogens within the gland. The result is intrapancreatic activation of trypsinogen, which causes a cascade of enzyme activation. Enterokinase is membrane bound in the intestine. Acinar cell secretions are not inhibited. Gallstones rarely form within the pancreas itself. Obstructive jaundice may also occur with gallstones, but it is is not the cause of pancreatitis.
• 46
  Why does pancreatitis have a high mortality?
  Difficulty: Easy     Topic: Pancreatitis 2
  a

  Acute onset of diabetes

  b

  Loss of pancreatic exocrine function

  c

  Pseudocyst formation with malignant transformation

  d

  Splenic artery erosion is common

  e

  Systemic inflammation causes multi-organ failure
  Explanation: Pancreatitis stimulates a massive systemic inflammatory response that spreads to other organs. The effect is dysfunction that may result in multi-organ failure. Chronic pancreatitis may cause diabetes. Loss of exocrine function is not life-threatening acutely. Malignant transformation of a pseudocyst is extremely rare. Splenic artery erosion is not common.
• 47
  In pancreatic exocrine failure, which enzyme will be low in the faeces?
  Difficulty: Hard     Topic: Chronic pancreatitis
  a

  Cholecystokinin

  b

  Elastase

  c

  Lactoferrin

  d

  Lysozyme

  e

  Pepsin
  Explanation: Low levels of faecal elastase is a sensitive test for pancreatic exocrine function as elastase is not produced in significant quantities elsewhere in the GIT. The other enzymes and hormones listed are relatively unaffected in chronic pancreatitis.
• 48
  What is the role of salivary lactoferrin?
  Difficulty: Medium     Topic: Salivary glands 1
  a

  Cleave iron from haem molecules

  b

  Facilitate iron absorption

  c

  Increase bacterial iron levels

  d

  Maintain iron in Fe2+

  e

  Sequester iron away from bacteria
  Explanation: Lactoferrin is a protein that binds iron to reduce iron levels in bacteria. Iron is an essential mineral for bacterial replication. Haem is absorbed intact in the small bowel. Ferric reductase maintains iron in a Fe2+ state.
• 49
  What peptide is involved in the initiation of the migratory motor complex?
  Difficulty: Hard     Topic: Migratory motor complex
  a

  Cholecystokinin

  b

  Gastrin

  c

  Ghrelin

  d

  Motilin

  e

  Secretin
  Explanation: The migratory motor complex is a form of GI motility that occurs in the fasting state. It is activated by secretion of motilin in the stomach that stimulates contractions that sweep from the gastric antrum to the terminal ileum. It acts to clear the intestine of undigested material.
• 50
  Which cranial nerves form the efferent limb of the swallowing reflex?
  Difficulty: Easy     Topic: Swallowing
  a

  IX and X

  b

  IX and XI

  c

  IX and XII

  d

  X and XI

  e

  X and XII
  Explanation: The glossopharyngeal (IX) and vagus (X) nerves are most important in the swallowing reflex. IX is activated by contact on the posterior pharyngeal wall, which stimulates a bilateral output through IX and X for: pharyngeal contraction, soft palate contraction, upper oesophageal sphincter relaxation and closure of the epiglottis over the laryngeal inlet.
• 51
  What name is given to the condition of failure of relaxation of the lower oesophageal sphincter?
  Difficulty: Easy     Topic: Achalasia
  a

  Achalasia

  b

  Bulbar palsy

  c

  Hirschprung's disease

  d

  GORD

  e

  Odynophagia
  Explanation: Achalasia is a condition that causes difficulty in swallowing and regurgitation of food because the lower oesophageal sphincter fails to relax. It may be idiopathic in origin or secondary to infections or malignancy. Bulbar palsy is a neuropathy of cranial nerves IX-XII. Hirschprung's disease causes absence of colonic myenteric plexus with an absence of motility. Gastro-oesophagel reflux disease is an inability of closure of the lower oesophageal sphincter. Odynophagia is the symptom of painful swallowing.
• 52
  Which drug increases GI motility by binding chemoreceptors and activating the myenteric plexus?
  Difficulty: Easy     Topic: Laxatives
  a

  Docusate

  b

  Fybogel

  c

  Lactulose

  d

  Loperamide

  e

  Senna
  Explanation: Senna is a stimulant laxative thats binds specific chemoreceptors and thereby causes activation of the myenteric plexus to increase bowel motility. Docusate sodium is a stool softener. Fybogel is a bulk-forming laxative composed of indigestible fibre that swells, causing bowel distension and stimulating motility. Lactulose is an osmotic laxative - lactulose cannot be broken down so water is retained in the lumen by osmosis. Lopermide is an opiate therefore is constipating and helps treat diarrhoea.
• 53
  What is the main mechanism by which statins reduce serum cholesterol levels?
  Difficulty: Easy     Topic: Stains
  a

  Increasing HDL production

  b

  Increasing LDL uptake in liver

  c

  Increasing VLDL uptake in liver

  d

  Reducing chylomicron production

  e

  Reducing LDL production
  Explanation: Statins are inhibitors of HMG-CoA-reductase, the first step in the synthesis of cholesterol. This reduces cholesterol production in the liver but the downstream effect is an increase in the number of LDL-receptors. This causes an increase in LDL uptake, which is the main method of reducing serum cholesterol levels. There is little effect on HDL, VDL or chylomicrons.
• 54
  Which part of the brain provides the output for the vomiting reflex?
  Difficulty: Easy     Topic: Emesis 1
  a

  Caudate nucleus

  b

  Chemoreceptor trigger zone

  c

  Hypothalamus

  d

  Reticular formation

  e

  Vomiting centre
  Explanation: The vomiting centre is part of the medulla that contains the output neurones for the vomiting reflex. This involves: gastric contraction, lower oesophageal sphincter relaxation, retrograde oesophageal peristalsis and inhibition of respiration. The chemoreceptor trigger zone is involved in responding to systemic pro-emetic stimuli and activating the vomiting centre.
• 55
  Through which receptor do neurones from the inner ear stimulate emesis?
  Difficulty: Medium     Topic: Emesis 2
  a

  5-HT-receptor

  b

  Cannabinoid-receptor

  c

  Dopamine-receptor

  d

  Histamine-1-receptor

  e

  Muscarinic acetylcholine-receptor
  Explanation: The inner ear and vestibular system stimulates emesis by direct neural connections onto the vomiting centre, which release histamine that binds H1-receptors. Cannabinoid receptors are also found on the vomiting centre. Damage to the GIT is signalled through serotonergic neurones and systemic release that binds 5-HT3-receptors on the chemoreceptor trigger zone (CTZ). Dopamine and muscarinic receptors are also found on the CTZ.
• 56
  To which epithelial type does the lower oesophagus change to following chronic acid reflux?
  Difficulty: Easy     Topic: Chronic oesophageal reflux
  a

  Pseudostratified columnar

  b

  Simple columnar

  c

  Simple stratified

  d

  Stratified columnar

  e

  Stratified squamous
  Explanation: Chronic reflux oesophagitis causes metaplasia of the oesophagus' normal stratified squamous epithelium into simple columnar with goblet cells and glands. This is known as Barrett's oesophagus and is a pre-malignant lesion by increasing the risk of change into adenocarcinoma.
• 57
  Which cell type releases a peptide that is necessary for vitamin B12 absorption?
  Difficulty: Easy     Topic: B12 absorption
  a

  APUD cells

  b

  Chief cell

  c

  D-cells

  d

  ECL cells

  e

  Parietal cell
  Explanation: Vitamin B12 must bind to intrinsic factor (IF), a substance released by gastric parietal cells, in order to be absorbed. The IF-B12 complexes pass to the terminal ileum where they bind the IF-receptor and the whole complex is internalised. APUD cells make many hormones. Chief cells produce pepsin. D-cells make somatostatin. ECL cells secrete histamine.
• 58
  Approximately, what percentage of total hepatic blood flow comes from the portal vein?
  Difficulty: Hard     Topic: Hepatic blood flow
  a

  20%

  b

  40%

  c

  60%

  d

  80%

  e

  100%
  Explanation: The liver has blood supply from two vessels: the portal vein provides 80% flow and the hepatic artery 20% flow however both vessels equally contribute to oxygen delivery. THe hepatic artery is a branch of the coeliac trunk. The portal vein is formed from the splenic vein and superior mesenteric vein.
• 59
  Where does the porta hepatis lie?
  Difficulty: Medium     Topic: Porta hepatis
  a

  Between the caudate and quadrate lobes

  b

  Inferior to the neck of the gall bladder

  c

  Lateral to the IVC

  d

  On the bare area of the liver

  e

  On the anterior surface of the right lobe
  Explanation: The porta hepatis is an area on the posterior surface of the liver where the hepatic artery and portal vein enter, and the common hepatic duct leaves, the liver. It is located superior to the quadrate lobe, inferior to the caudate lobe, immediately medial to the IVC and slightly superior to the gall bladder neck. The bare area of the liver is superiorly and is in direct contact with the diaphragm.
• 60
  What arrangement of liver architecture is described by a ‘classical lobule’?
  Difficulty: Easy     Topic: Hepatic ultrastructure
  a

  1 portal triad and 1 hepatic vein

  b

  2 hepatic veins at the periphery with 2 portal triads in the middle

  c

  3 hepatic veins at the periphery with a portal triads in the middle

  d

  6 hepatic veins at the periphery and 6 portal triads in the middle

  e

  6 portal triads at the periphery with a hepatic vein in the middle
  Explanation: Liver architecture can be described in 3 main ways. A classic lobule is composed of 6 portal triads at the periphery with a hepatic venule in the centre. A portal lobule is the reverse with a central portal triad and 3 hepatic veins at the periphery - showing the flow of bile towards the centre. A hepatic acinus illustrates decreasing oxygen concentration from 2 portal triads out to 2 peripheral hepatic venules.
• 61
  What cell type commonly resides in the space of Disse?
  Difficulty: Medium     Topic: Space of Disse
  a

  Endothelial cell

  b

  Hepatocyte

  c

  Kupffer cell

  d

  Plasma cell

  e

  Stellate cell
  Explanation: The space of Disse is a microscopic area located between hepatic sinusoidal endothelial cells and hepatocytes. It is the location of stellate cells, which become active during inflammation and produce fibrous tissue. Kupffer cells are found within the sinusoidal lumen. Very few plasma cells are resident in the liver in the absence of pathology.
• 62
  What is the role of phosphoglucomutase?
  Difficulty: Easy     Topic: Phosphoglucomutase
  a

  Adds glucose residues to glycogen

  b

  Cleaves glucose residues from glycogen

  c

  Conversion between forms of glucose-phosphate

  d

  Dephosphorylates glucose

  e

  Initiates glycogen synthesis
  Explanation: Phosphoglucomutase (PGM) converts glucose-1-phosphate to glucose-6-phosphate and back. When glucose is added to, or cleaved from, glycogen it is in the form of G-1-P. But hexokinase forms G-6-P and for glucose to leave the cell glucose-6-phosphatase removes the phosphate residue from the 6'position.