NDM Midsemester Exam 2008

1

In human metabolism, as measured in an Atwater Chamber, which of the following statements is CORRECT?


  One gram of alcohol yields more metabolic energy than one gram of fat.

  One gram of protein yields more metabolic energy than one gram of carbohydrate.

  Dietary fat is commonly metabolised with 99% or better conversion of consumed material to heat.

  All cellulose will be voided as fibre and no heat production is measured.

  Of the major fuels, proteins produce the lowest % efficiency of heat, relative to heat measured in a bomb calorimeter.

2

In reviewing human history, diet and anatomical characteristics, which one of the following statements is the best response?


  There have been numerous vegetarian communities dating back to stone-age times.

  Hunter-gatherer communities typically exhibit poor health as shown by the skeletal remains of stone-age humans.

  The human gastrointestinal tract is omnivorous in character.

  The human gastrointestinal tract is carnivorous in character.

  By observing other primates, Katharine Milton has hypothesised that human forebears in Africa developed intelligence and communication to hunt migratory animals.

3

Willett and Stampfer created a pyramid in 2003 that is generally considered to be the best summary of current dietary recommendations. Which of the following was NOT a recommendation by Willett and Stampfer?


  Daily exercise should form the base for a healthy life style.

  Consume unsaturated plant oils (e.g. olive oil) in liberal amounts.

  Consume red meats in liberal amounts.

  Consume alcohol (in moderation).

  Consume potato and pasta in sparing amounts only.

4

In respect to vitamins which of the following statements is CORRECT?


  Water-soluble vitamins are too low in concentrations in meat to be a significant dietary source for human nutrition.

  Water-soluble vitamins generate long-term stores in humans that can be used over periods up to a year.

  The water soluble vitamins include thiamin, niacin, riboflavin, biotin, pantothenic acid, pyridoxine (B6), folate, vitamin B12 and Vitamin E.

  Thiamin deficiency is the most common encountered in Australia and can progress to Wernicke’s Encephalopathy.

  Supplementation with folate during pregnancy reduces the incidence of gestational diabetes.

5

In respect to glycogen and related metabolism which of the following statements is CORRECT?


  Glycogen is an a1-4 linked polymer of glucose with a1-6 branching.

  Glycogen synthase uses ATP as an energy source to carry out the polymer formation.

  In the fed state up to 20 grams of glucose can be stored as glycogen in the liver and this is enough to supply the brain with glucose during an overnight fast.

  The release of glucose to the circulation from glycogen stores (or gluconeogenesis) requires the enzyme glucose-6-phosphatase and this enzyme is only active in liver and muscle.

  Glycogen is phosphorylysed to glucose-6-phosphate in a single step by the enzyme phosphorylase.

6

In respect to the Krebs Cycle which of the following statements is CORRECT?


  The two carbons in acetyl-CoA are fully oxidized to CO2 by combination with molecular O2 in aerobic metabolism.

  Hydrogen generated by one acetyl-CoA entering the Krebs Cycle is preserved as 5 NADH and one FADH2.

  The Krebs Cycle begins when acetyl-CoA condenses with the 4-carbon compound malic acid to create the six carbon compound citric acid.

  A decarboxylation of isocitrate produces a-ketoglutarate. a-Ketoglutarate is then decaboxylated to form succinyl-CoA.

  Carbon can be added to the cycle at points additional to acetyl-CoA, most significantly by the breakdown of amino acids to citrate.

7

In respect to aspects of fat metabolism which of the following statements is CORRECT?


  Cyclic AMP is a second messenger and a cellular signal to activate fed-state metabolism including fat synthesis.

  Ketosis can be produced by high fat content in the diet (e.g. the Atkins diet).

  ß-oxidation in mitochondria is a repeated cycle in which the two carbons next to the CoA of a fatty-acyl-CoA are removed as malonyl CoA.

  Fatty acid synthesis proceeds using mitochondrial fatty acid synthase when excess acetyl-CoA is produced in mitochondria from glucose, alcohol or amino acids.

  Creatine transports fatty-acyl-CoA (as fatty-acyl-creatine) into mitochondria for oxidation.

8

In respect to adiponectin which of the following statements is CORRECT?


  Adiponectin is a steroid hormone secreted by adipocytes.

  Adiponectin promotes inflammation which contributes to the health problems of obese people.

  Glitazones treat diabetes by supressing adiponectin secretion.

  All of the above are true.

  None of the above is true.

9

The internal (deep) inguinal ring is a deficiency in which of the following structures?


  External Oblique.

  Internal Oblique.

  Transversus abdominus.

  Fascis Transversalis.

  Rectus Abdominus.

10

The anterior compartment of the thoracolumbar fascia encloses which of the following structures?


  Psoas Major.

  Psoas Minor.

  Quadratus Lumborum.

  Iliacus.

  Erector Spinae.

11

The accessory pancreatic duct drains into:


  the main pancreatic duct.

  the second part of the duodenum proximal to the ampulla of Vater.

  the second part of the duodenum distal to the ampulla of Vater.

  the duodenal-jejeunal flexure.

  none of the above.

12

Which of these statements concerning control of water and electrolyte secretion through the Enteric Nervous System is NOT CORRECT?


  The major secretomotor transmitters in the intestine are acetylcholine and vasoactive intestinal peptide

  Enteric reflexes act to return fluid to the lumen of the small intestine.

  Enteric secretomotor reflexes are under central inhibitory control via sympathetic pathways.

  Enteric reflexes controlling transmucosal fluid exchange are prominent in the stomach.

  Mucosal secretion and blood flow are locally co-ordinated in the small intestine.

13

Which one of the following statements concerning type 1 diabetes mellitus (DM) is NOT CORRECT?


  Type 1 DM is associated with an increased risk of peripheral neuropathy.

  The majority of patients with type 1 DM have autoantibodies against islet cell antigens.

  Type 1 DM is associated with HLA DR3 and/or DR4.

  The onset of type 1 DM is followed by the development of insulitis, which is inflammation of the islets of Langerhans.

  There is an association between type 1 DM and other forms of autoimmune disease, such as thyroiditis.

14

During exercise at ~75% of maximal aerobic capacity the major fuel for contracting skeletal muscle is:


  Muscle glycogen.

  Intramuscular triglyceride.

  Lactate.

  Creatine phosphate.

  Plasma free fatty acids.

15

Visceral obesity is associated with an increased risk of metabolic disease. An important intramuscular characteristic related to a lower accumulation of visceral fat is:


  Low muscle glycogen levels.

  Reduced CPT1 activity.

  Reduced GLUT4 expression.

  Reduced mitochondrial density.

  Increased activity of ß-oxidative enzymes.

16

As starvation progresses from day 1 to day 4, which of the following would certainly NOT be observed?


  Less that 2mM change in blood glucose level.

  Increased production of ketone bodies.

  Breakdown of muscle protein to provide amino acids as fuel.

  Increased plasma free fatty acid levels.

  Increased plasma chylomicron levels.

17

Which of the following statements about the metabolism of ketone bodies is CORRECT?


  Acetyl-CoA is consumed as a substrate during the synthesis of ketone bodies.

  For use as fuel, acetoacetate must be oxidised to ß-hydroxybutyrate.

  Ketone bodies become the main fuel for the brain after 1 day of starvation.

  Skeletal muscle lacks the enzymes to use ketone bodies as fuel.

  The synthesis of ketone bodies inhibits ß oxidation of fatty acids in liver protein.

18

Which of the following statements about the insulin antagonists adrenaline, glucagon and cortisol is CORRECT?


  The major target tissue for adrenaline is the liver.

  Glucagon acts via a nuclear receptor.

  An early cellular event following adrenaline binding is activation of adenylate cyclase.

  Glucagon increases the activity of glycogen phosphorylase via inhibition of phosphorylase kinase.

  Cortisol stimulates the synthesis of skeletal muscle.

19

Which of the following statements about the metabolic interaction between the liver and extrahepatic tissues is CORRECT?


  The liver packages triacylglycerols into LDL for transport to adipose tissue.

  Ketone bodies from liver are only significantly used as a fuel by the brain.

  Free fatty acids from adipose tissue are used for gluconeogenesis in liver during starvation.

  Lactate derived from anaerobic muscle activity is used for gluconeogenesis in the liver.

  Plasma leucine derived from turnover of muscle protein is a well characterised source of carbon for gluconeogenesis in the liver.

20

Which of the following statements about LDL metabolism is CORRECT?


  Familial hypercholesterolaemia (FH) is caused by mutations that inactivate the LDL receptor.

  Mutations in the lipoprotein lipase gene lead to increased levels of LDL cholesterol.

  Patients with FH have high plasma levels of HDL cholesterol.

  Mutations in the ApoA-1 gene lead to the accumulation of plasma LDL.

  Oxidation of LDL in vessel walls is beneficial in minimising deposition of atherosclerotic plaque.

21

With regard to smooth muscle structure or function, which of the following is NOT CORRECT?


  Thick filaments are scarce while thin filaments are plentiful.

  Smooth muscle generates the same force per cross-sectional area as skeletal muscle.

  'Cost' (rate of ATP utilisation) is less for smooth than for skeletal muscle.

  Contraction rate is comparable for both smooth and skeletal muscle.

  Smooth muscle cells can contract to a small percentage of their initial length.

22

Which of the following is NOT an action of GLP-1?


  Stimulation of insulin secretion.

  Suppression of hunger.

  Slowing of gastric emptying.

  Inhibition of somatostatin secretion.

  Inhibitition of glucagon secretion.

23

Which of the following statements about aMSH is NOT correct?


  aMSH is produced as a fragment of ACTH.

  aMSH is derived from pro-opiomelanocortin.

  aMSH stimulates food intake.

  aMSH binds to the melanocortin 4 receptor.

  aMSH is found in neurones located in the arcuate nucleus of the hypothalamus.

24

Which of the following statements is NOT CORRECT about anorexia nervosa?


  Anorexia nervosa can begin at any age.

  There is evidence that there is a genetic predisposition to anorexia nervosa.

  Anorexia nervosa is associated with a distorted body image.

  Bradycardia, and anaemia are features of anorexia nervosa.

  Decreased 5-HT2A receptor binding has been implicated as a possible cause of anorexia nervosa.

25

Which of the following statements regarding eicosanoids is/are CORRECT? A) Preformed PGD2 is stored in the granules of mast cells. B) Prostaglandins produce their biological activities through activation of G-protein coupled receptors. C) Thromboxane A2 (TXA2) is a potent vasodilator. D) Prostaglandins can be synthesised by most cells.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.

26

Which of the following statements related to gastrin is/are CORRECT? A) Gastrin increases pepsinogen secretion. B) Gastrin acts on oxyntic (parietal) cell to increase H+ secretion. C) Gastrin decreases tone of gastro-oesophageal sphincter. D) Gastrin receptors are present on the oxyntic (parietal) cell.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.

27

Which of the following statements related to gastric acid secretion is/are CORRECT? A) The effects on acid secretion of acetyl choline and gastrin are additive. B) The effects on acid secretion of histamine and gastrin are additive. C) The effects on acid secretion of acetyl choline and histamine are additive. D) Acid secretion is inhibited by sodium bicarbonate.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.

28

Which of the following statements related to peptic ulceration is/are CORRECT? A) Histamine increases acid secretion by a direct effect on the peptic cell. B) The use of proton pump inhibitors is the most effective way to block acid secretion. C) Gastrin increases acid secretion by a direct effect on the oxyntic (parietal)cell. D) Most peptic ulcers can be healed by inhibiting acid secretion.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.

29

Which of the following statements related to the absorption of food is/are CORRECT? A) The lower pH of the unstirred layer is critical for the absorption of complex lipids. B) Bile salts are essential for micelle formation. C) Fatty acids allow emulsification of lipids (fats). D) Chylomicron formation depends upon bile salts.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.

30

Which of the following statements related to the pancreas and its secretion is/are CORRECT? A) Pancreatic acinar cell secretions are stimulated by vagal activity. B) a amylase digests starches to disaccharides. C) Pancreatic duct cell secretions are stimulated by secretin. D) Insulin is secreted from a cells of the pancreas.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.