Physiology - ACEM exam Feb 2015

Question 1

Glucagon
A) promotes glycogenolysis by activating adenylyl cyclase in the hepatic cell membrane
B) is a larger polypeptide than insulin
C) is secreted primarily from the D cells of the pancreas
D) secretion is stimulated by insulin

Answer 1

A.
Ganong 24th ed p.443-445
Glucagon is a 29-amino acid linear polypeptide chain with molecular weight 3485. Insulin is a two-chain polypeptide, one with 21 amino acids, one with 30 amino acids, and the molecular weight is 5808.
Insulin is an inhibitor of glucagon secretion.
Glucagon induces glycogenolysis in hepatic cells by two mechanisms:
1) G-protein –> adenylyl cyclase activation
2) G-protein –> phospholipase C –> calcium

Question 2

Which of the following has the most potent glucocorticoid activity?
A) corticosterone
B) cortisol
C) cortisone
D) deoxycorticosterone

Answer 2

B.
Ganong 24th ed p.361, table 20-2
In decreasing order of glucocorticoid activity:
Dexamethasone&raquo_space;> 9-alpha-Fluorocortisol&raquo_space; Prednisolone > Cortisol > Cortisone > Corticosterone = Aldosterone > Deoxycorticosterone

Question 3

1,25 dihydroxycholecalciferol
A) is an unbound hormone in plasma
B) binds to a cytoplasmic receptor to mediate its function in intestinal cells
C) is produced in liver cells from calcidiol
D) production is increased by high phosphate levels in plasma

Answer 3

B.
Ganong 24th ed p.379-380
1,25-dihydroxycholecalciferol is also called calcitriol. It is produced in the proximal tubule cells of the kidney, from calcidiol, which comes from the liver. Production of calcitriol is decreased by high phosphate levels. Its receptor is a transcriptional regulator. Each form of vitamin D is hydrophobic, and is transported in blood bound to carrier proteins.

Question 4

After fasting for one week, the major source of blood glucose is
A) gluconeogenesis from fatty acids
B) glycogenolysis and gluconeogenesis from fatty acids
C) glycogenolysis and gluconeogenesis from amino acids and glycerol
D) gluconeogenesis from amino acids and glycerol

Answer 4

D.
Ganong 24th ed p.25
Liver and muscle stores of glycogen are exhausted in the first 24-48hrs of starvation.
Gluconeogenesis occurs from amino acids and glycerol, but cannot occur from fatty acids.
Fatty acids are converted to ketone bodies.

Question 5

After fasting for one week, the major source of blood glucose is
A) gluconeogenesis from fatty acids
B) glycogenolysis and gluconeogenesis from fatty acids
C) glycogenolysis and gluconeogenesis from amino acids and glycerol
D) gluconeogenesis from amino acids and glycerol

Answer 5

D.
Ganong 24th ed p.25
Liver and muscle stores of glycogen are exhausted in the first 24-48hrs of starvation.
Gluconeogenesis occurs from amino acids and glycerol, but cannot occur from fatty acids.
Fatty acids are converted to ketone bodies.

Question 6

With relation to the exocrine portion of the pancreas
A) acetylcholine causes the inhibition of secretin
B) cholecystokinin stimulates the production of pancreatic enzymes
C) pancreatic juice is mainly excreted as active enzymes
D) secretin inhibits secretion of pancreatic enzymes

Answer 6

C (but I think this is wrong – C should read “inactive”, not “active”)
Ganong 24th ed p.463-464
Acetylcholine stimulates acinar cells to release zymogens. I don’t think it inhibits secretin.
CCK stimulates pancreatic enzyme secretion, but not production.
Most of the enzymes in pancreatic juice are released in their inactive forms, and only activated when they reach the intestinal lumen.
Secretin augments this action of CCK, as well as stimulating bicarbonate secretion.

Question 7

With relation to the exocrine portion of the pancreas
A) acetylcholine causes the inhibition of secretin
B) cholecystokinin stimulates the production of pancreatic enzymes
C) pancreatic juice is mainly excreted as active enzymes
D) secretin inhibits secretion of pancreatic enzymes

Answer 7

C (but I think this is wrong – C should read “inactive”, not “active”)
Ganong 24th ed p.463-464
Acetylcholine stimulates acinar cells to release zymogens. I don’t think it inhibits secretin.
CCK stimulates pancreatic enzyme secretion, but not production.
Most of the enzymes in pancreatic juice are released in their inactive forms, and only activated when they reach the intestinal lumen.
Secretin augments this action of CCK, as well as stimulating bicarbonate secretion.

Question 8

Defecation
A) ceases during starvation
B) depends on a stretch reflex which involves primarily lumbar segments of the spinal cord
C) does not affect venous return to the heart
D) tends to follow a gastrocolic reflex

Answer 8

D.

The nerve supply to the external anal sphincter comes from the pudendal nerve (S2-S4)

Question 9

Which of the following increases gastrin secretion
A) adrenaline
B) glucagon
C) secretin
D) somatostatin

Answer 9

A.

See Ganong 24th ed table 25-6

Question 10

Which of the following increases gastrin secretion
A) adrenaline
B) glucagon
C) secretin
D) somatostatin

Answer 10

A.

See Ganong 24th ed table 25-6

Question 11

With respect to protein digestion and absorption
A) gastrointestinal absorption of amino acids is coupled to ion transport
B) amino acid absorption is rapid in the ileum
C) pepsins have a pH optimum of 5.6 to 7.2
D) pepsins are serine peptidases

Answer 11

A.
Ganong 24th ed. Early chapter 26
Most of the absorption of amino acids from the lumen into the enterocyte is via cotransport with sodium ions or chloride ions.
Absorption of amino acids is rapid in the duodenum and jejunum. It occurs less in the ileum because
the majority of free amino acids have already been assimilated at that point.
Pepsins have a pH optimum of 1.6 to 3.2

Question 12

With respect to protein digestion and absorption
A) gastrointestinal absorption of amino acids is coupled to ion transport
B) amino acid absorption is rapid in the ileum
C) pepsins have a pH optimum of 5.6 to 7.2
D) pepsins are serine peptidases

Answer 12

A.
Ganong 24th ed. Early chapter 26
Most of the absorption of amino acids from the lumen into the enterocyte is via cotransport with sodium ions or chloride ions.
Absorption of amino acids is rapid in the duodenum and jejunum. It occurs less in the ileum because
the majority of free amino acids have already been assimilated at that point.
Pepsins have a pH optimum of 1.6 to 3.2

Question 13

Absorption from the gastrointestinal tract of
A) calcium depends entirely on normally functioning kidneys
B) glucose is passive and does not require energy
C) iron is independent of its rate of utilisation
D) most water soluble vitamins occurs chiefly in the proximal small bowel

Answer 13

D.
Ganong 24th ed chapter 26
Sodium-Glucose cotransporters act without using ATP directly, but the energy for glucose transport is provided indirectly, by the active transport of sodium out of the cell, to maintain the concentration gradient.
Intestinal absorption of iron is regulated by the balance of input vs. use (in erythropoiesis) vs. stores available.
Most water-soluble vitamins are absorbed in the proximal small bowel, except for vitamin B12, which is absorbed in the ileum. Fat-soluble vitamins are absorbed throughout the small bowel.

Question 14

Absorption from the gastrointestinal tract of
A) calcium depends entirely on normally functioning kidneys
B) glucose is passive and does not require energy
C) iron is independent of its rate of utilisation
D) most water soluble vitamins occurs chiefly in the proximal small bowel

Answer 14

D.
Ganong 24th ed chapter 26
Sodium-Glucose cotransporters act without using ATP directly, but the energy for glucose transport is provided indirectly, by the active transport of sodium out of the cell, to maintain the concentration gradient.
Intestinal absorption of iron is regulated by the balance of input vs. use (in erythropoiesis) vs. stores available.
Most water-soluble vitamins are absorbed in the proximal small bowel, except for vitamin B12, which is absorbed in the ileum. Fat-soluble vitamins are absorbed throughout the small bowel.

Question 15

Regarding platelets
A) both platelets and blood vessel walls contain von Willebrand factor
B) platelet binding of thrombopoietin stimulates platelet production
C) splenectomy helps decrease platelet numbers
D) they have a half-life of four days

Answer 15

D.
Ganong’s 24th ed chapter 31
Von Willebrand factor is found on subendothelial surfaces. Platelets have GpIb and GpIIb-IIa receptors on their surface.
Thrombopoietin stimulates platelet production by facilitating megakaryocyte maturation in the bone marrow.
Splenectomy causes thrombocytosis.

Question 16

Regarding platelets
A) both platelets and blood vessel walls contain von Willebrand factor
B) platelet binding of thrombopoietin stimulates platelet production
C) splenectomy helps decrease platelet numbers
D) they have a half-life of four days

Answer 16

D.
Ganong’s 24th ed chapter 31
Von Willebrand factor is found on subendothelial surfaces. Platelets have GpIb and GpIIb-IIa receptors on their surface.
Thrombopoietin stimulates platelet production by facilitating megakaryocyte maturation in the bone marrow.
Splenectomy causes thrombocytosis.

Question 17

Regarding myocardial contractility
A) as the heart rate increases, myocardial contractility decreases
B) glucagon is positively inotropic
C) post-extrasystolic potentiation is dependent upon ventricular filling
D) vagal stimulation has a negatively inotropic effect on atrial muscle but no effect on ventricular muscle.

Answer 17

B.
Large doses of exogenous glucagon exert a positively inotropic effect on the heart.
Ganong’s 24th ed chapter 30 says: There is a negative inotropic effect of vagal stimulation on both atrial and (to a lesser extent) ventricular muscle.
Also: Ventricular extrasystoles condition the myocardium in such a way that the next succeeding contraction is stronger than the preceding normal contraction. This postextrasystolic potentiation is independent of ventricular filling – it is due to increased availability of intracellular calcium.
Also: Myocardial contractility increases as the heart rate increases, although this effect is relatively small.

Question 18

Regarding myocardial contractility
A) as the heart rate increases, myocardial contractility decreases
B) glucagon is positively inotropic
C) post-extrasystolic potentiation is dependent upon ventricular filling
D) vagal stimulation has a negatively inotropic effect on atrial muscle but no effect on ventricular muscle.

Answer 18

B.
Large doses of exogenous glucagon exert a positively inotropic effect on the heart.
Ganong’s 24th ed chapter 30 says: There is a negative inotropic effect of vagal stimulation on both atrial and (to a lesser extent) ventricular muscle.
Also: Ventricular extrasystoles condition the myocardium in such a way that the next succeeding contraction is stronger than the preceding normal contraction. This postextrasystolic potentiation is independent of ventricular filling – it is due to increased availability of intracellular calcium.
Also: Myocardial contractility increases as the heart rate increases, although this effect is relatively small.

Question 19

End-diastolic volume is increased by all of the following EXCEPT:
A) decreased ventricular compliance
B) increased cardiac muscle fibre length
C) negative intrathoracic pressure
D) venous constriction

Answer 19

A.

Question 20

End-diastolic volume is increased by all of the following EXCEPT:
A) decreased ventricular compliance
B) increased cardiac muscle fibre length
C) negative intrathoracic pressure
D) venous constriction

Answer 20

A.

Question 21

When treating a patient with heart failure, which of the following factors will be LEAST likely to depress contractility further
A) acidosis
B) barbiturates
C) hypocapnia
D) hypoxia

Answer 21

C.
Ganong’s 24th ed chapter 30
Hypercapnia, Hypoxia, Acidosis, Barbiturates, Quinidine, Procainamide – these all depress myocardial contractility.

Question 22

When treating a patient with heart failure, which of the following factors will be LEAST likely to depress contractility further
A) acidosis
B) barbiturates
C) hypocapnia
D) hypoxia

Answer 22

C.
Ganong’s 24th ed chapter 30
Hypercapnia, Hypoxia, Acidosis, Barbiturates, Quinidine, Procainamide – these all depress myocardial contractility.

Question 23

An elderly lady presents with oedema due to cardiac failure.  The likely cause of the oedema is
A) lowered oncotic pressure
B) lowered venous pressure
C) raised oncotic pressure
D) raised venous pressure

Answer 23

D.

Question 24

Which of the following is a cause of increased interstitial fluid and oedema
A) accumulation of osmotically active substances in the intracellular space
B) exercising muscles
C) increased plasma protein level
D) type II respiratory failure

Answer 24

B.

Question 25

Which of the following is a cause of increased interstitial fluid and oedema
A) accumulation of osmotically active substances in the intracellular space
B) exercising muscles
C) increased plasma protein level
D) type II respiratory failure

Answer 25

B.

Question 26

The Valsalva manoeuvre has which one of the following characteristics
A) it produces a strongly negative intrapleural pressure
B) it is followed by a brief period of hypertension and slowing of the heart
C) it may decrease peripheral vascular resistance
D) sympathectomised patients show no change in heart rate or blood pressure

Answer 26

B.

Question 27

The Valsalva manoeuvre has which one of the following characteristics
A) it produces a strongly negative intrapleural pressure
B) it is followed by a brief period of hypertension and slowing of the heart
C) it may decrease peripheral vascular resistance
D) sympathectomised patients show no change in heart rate or blood pressure

Answer 27

B.

Question 28

Insulin secretion is inhibited by
A) acetylcholine
B) amino acids including leucine and arginine
C) caffeine
D) potassium depletion

Answer 28

D.
Ganong’s 24th ed Table 24-4
Theophylline and caffeine are structurally similar: They both stimulate insulin secretion.
Theophylline, amino acids and acetylcholine all stimulate insulin secretion AND glucagon secretion.
Potassium depletion inhibits insulin secretion.

Question 29

Insulin secretion is inhibited by
A) acetylcholine
B) amino acids including leucine and arginine
C) caffeine
D) potassium depletion

Answer 29

D.
Ganong’s 24th ed Table 24-4
Theophylline and caffeine are structurally similar: They both stimulate insulin secretion.
Theophylline, amino acids and acetylcholine all stimulate insulin secretion AND glucagon secretion.
Potassium depletion inhibits insulin secretion.

Question 30

STEM:
A) brain
B) heart muscle
C) kidneys
D) liver
E) skeletal muscle
F) skin

In health, at rest, which organ has the least arterio-venous oxygen difference?

Answer 30

C.

Question 31

STEM:
A) brain
B) heart muscle
C) kidneys
D) liver
E) skeletal muscle
F) skin

In health, at rest, which organ has the highest arterio-venous oxygen difference?

Answer 31

B.

Ganong’s 24th ed Table 33-1

Question 32

Which of the following statements is INCORRECT:
A) Thyroid hormones exert their effects via cell membrane receptors
B) Thyroid hormones increase the oxygen consumption of almost all metabolically active tissues
C) Thyroid hormones lower circulating cholesterol levels
D) Thyroid hormones increase the number and affinity of beta-adrenergic receptors in the heart

Answer 32

A.
Ganong’s 24th ed Table 19-5
Thyroid hormones are relatively lipophilic, and are >99% protein-bound. It is the small amount of free thyroid hormone that is physiologically active. T3 and T4 cross the cell membrane and bind to intracellular receptors, which then bind to DNA and alter gene expression. T3 and T4 increase the oxygen consumption of almost all metabolically active tissues. The exceptions are the adult brain, testes, lymph nodes, uterus, spleen and anterior pituitary. Thyroid hormones increase the number of LDL receptors in the liver, thereby increasing hepatic removal of cholesterol from the circulation.