2003 Primary Examination Workshop



2003 Primary Examination Workshop

Physiology MCQs

1. With regard to the defence of H+ concentration, all of the following are true EXCEPT:

A) Increased ventilation leads to decreased H+ concentration

B) Plasma proteins are an important buffer system in the blood

C) The phosphate buffering system is important intracellularly

D) Increased H+ concentration stimulates increased reabsorption of HCO3- in the kidneys

E) The secretion of H+ ions by the renal tubules is a passive process

2. During skeletal muscle contraction:

A) Calcium binds to troponin I

B) The length of the A band decreases

C) Energy is mainly derived from glucose at rest

D) Calcium is released from intracellular stores

E) More work is done in isometric than isovolumetric contraction

3. The oxygen dissociation curve is moved to the right by:

A) A decrease in 2, 3 DPG

B) A decrease in blood temperature

C) Foetal haemoglobin

D) The presence of carbon monoxide

E) A decrease in blood pH

4. Regarding CO2 transport:

A) Solubility of CO2 in blood is double that of O2

B) Binding of CO2 to Hb reduces the affinity for O2 – Haldane effects

C) CO2 molecule, when added to RBC, increases osmotically active particles

D) Carbamino compound is formed in plasma

E) 50ml of CO2 per minute is transported to lungs

5. An arterial blood gas taken from a patient breathing room air at sea level shows a PCO2 20, PO2 60, pH 7.52. Assuming a normal respiratory quotient, calculate the alveolar PO2

A) 80mmHg

B) 85mmHg

C) 150mmHg

D) 130mmHg

E) 125mmHg

6. The effects of exercise include:

A) An increase in arterial PCO2

B) An increase in respiratory quotient (R)

C) Pulmonary vasoconstriction

D) Systemic vasoconstriction

E) Left shift in the O2 dissociation curve

7. In dehydration:

A) Decreased vasopressin leads to water retention

B) Angiotensin II acts on the sub-fornical organ to produce thirst

C) The total intracellular fluid volume is maintained in moderate dehydration

D) Secretion of aldosterone decreases

E) Plasma osmolality can drop as low as 280 mosm/kg

8. Sodium reabsorption in the kidney is:

A) Actively transported in the thin portions of the loop of Henle

B) Coupled to the movement of glucose and amino acids in the distal tubule

C) Decreased by atrial natriuretic peptide

D) Reabsorbed against its concentration gradient

E) Independent of chloride absorption

9. Angiotensin II

A) Is one of the most potent vasodilators

B) Acts indirectly on the adrenal cortex

C) Acts on the brain to decrease the sensitivity of the baroreflex

D) Penetrates the blood – brain barrier

E) Inhibits the release of norepinephrine

10. Regarding temperature regulation:

A) Increased catecholamine secretion is an important endocrine response to heat

B) Anorexia is activated by cold

C) Aspirin has an antipyretic effect

D) Antibody production is decreased when body temperature is elevated

E) Reflex responses activated by cold are controlled from the anterior hypothalamus

11. Regarding Frank Starling curves:

A) The extent of afterload is proportionate to end diastolic volume

B) Cardiac muscle fibres are lengthened by decreased ventricular compliance

C) Contractility of myocardium is increased on standing

D) Sympathetic stimulation shifts the length/tension curve upward and to the right

E) Increased negative intrathoracic pressure increases contractility

12. Regarding synaptic transmission:

A) A synaptic cleft is 1000nm wide

B) Synapses allow retrograde transmission of action potentials

C) Presynaptic fibres end only on dendritic spines

D) The average neuron divides to over 2000 synaptic endings

E) Presynaptic knobs contribute only a small portion of the dendritic membrane area

13. Regarding coronary blood flow:

A) In most people, the left coronary artery supplies the sinoatrial node

B) Coronary flow occurs only during systole

C) Coronary flow is about 15% of cardiac output

D) The coronary sinus drains into the right atrium

E) B1 receptors in the arterial wall cause vasoconstriction

14. The knee jerk:

A) Utilises glutamates as the central synapse neurotransmitter

B) Is mediated by gamma afferents

C) Is a good example of a polysynaptic reflex arc

D) Involves relaxation of the antagonistic muscle due to the Golgi tendon organ

E) Is initiated by stimulation of the sensory extra fusal fibres

15. Regarding neuromuscular junction:

A) Dopamine is the neurotransmitter

B) Acetylcholine is the neurotransmitter

C) Binding of the neurotransmitter to the muscle causes influx of Ca++

D) Binding of the neurotransmitter to the muscle decreases the conductance of Na+ and K+ through the membrane

E) Neurotransmitter is removed from the synaptic cleft by re-uptake

16. Decreased extracellular fluid volume:

A) Increases angiotensin II levels

B) Is not caused by diarrhoea

C) Inhibits vasopressin secretion

D) Increases ANP levels

E) Is not caused by adrenal insufficiency

17. Regarding fatty acid metabolism:

A) Free fatty acids circulate bound to albumin

B) Free fatty acids are not an important source of energy for the heart

C) Insulin increases the activity of hormone sensitive lipase

D) LDL receptors recognise APO B48 but not APO B100 APO proteins

E) Cholesterol regulates its own synthesis by activating HMG-CoA reductase

18. Regarding alveolar stability:

A) Smaller alveoli require relatively lower pressures to prevent collapse

B) Low alveolar surface tension increases lung compliance

C) Compliance is a dynamic measure of lung and chest recoil

D) Surfactant increases lung surface tension

E) High alveolar surface tension helps prevent pulmonary oedema

19. Regarding Starlings forces:

A) Capillary pressure at the arteriole end is 15mmHg

B) Hydrostatic pressure exceeds oncotic pressure throughout the capillary

C) Capillary pressure at the venule end is 5mmHg

D) Interstitial colloid osmotic pressure is usually negligible

E) Capillary filtration coefficient decreases with capillary permeability

20. The actions of B1 receptors include:

A) Vasodilation in skeletal muscle

B) Renin secretions from juxta glomerular cells

C) Decreased insulin and glucagon secretion from pancreatic islet cells

D) Pilomotor muscle contraction in the skin

E) Gall bladder contraction

21. GFR:

A) Is higher per body surface area in women

B) Increases with a decrease in MAP

C) Normally 80% of filtrate is reabsorbed

D) Is accurately estimated by serum creatinine

E) Decreases with ureteral obstruction

22. Concerning capillary fluid exchange:

A) Venule constriction reduces filtration pressure

B) Hypoproteinaemia decreases fluid shift out of capillaries

C) Lymphoedema fluid has a low protein content

D) Substance P increases capillary permeability

E) Kinins reduce capillary permeability

23. Concerning the CSF:

A) H+ ions cross the blood - brain barrier into the CSF with ease

B) Approximately 1550mls of CSF is produced per day

C) Osmolality is less than that of plasma because of its lower protein content

D) CSF pressure is normally 70-180nm water

E) Formation of CSF increases when the CSF pressure drops

24. Acclimatisation to high altitude involves:

A) Decreased 2,3 DPG

B) Increased capillary number

C) Leftward shift of oxygen dissociation curve in response to respiratory acidosis

D) Pulmonary vasodilation

E) Chronic elevation of CSF pH

25. In the distal tubular cells:

A) K+ secretion is mainly by active transport mechanisms

B) K+ secretion is decreased in acidosis

C) K+ secretion is increased when Na+ delivery to the tubule is decreased

D) Loop diuretics will cause decreased K+ secretion

E) K+ is resorbed by the Na/K+/2Cl- transporter

26. Regarding Starlings forces:

A) Hydrostatic pressure gradient is the only force involved

B) Interstitial fluid pressure remains the same

C) Osmotic pressure gradient is not involved

D) Total diffusion is not flow limited

E) Transfer of substances that do not reach equilibrium is diffusion limited

27. In mammalian mixed nerves:

A) Type A beta fibres conduct motor impulses to muscle spindles

B) Type B fibres are preganglionic autonomic nerve fibres

C) Type C fibres have a diameter of 12-20µm

D) Type A fibres have a slower conduction velocity than type C fibres

E) Type A alpha fibres are concerned with touch and pressure

28. Regarding resting membrane potentials:

A) Changes in the external Na+ concentration affects the magnitude of the cardiac action potential

B) Changes in the external K+ concentration affects the magnitude of the action potential

C) The slow Ca 2+ channel is activated at the membrane potential of OmV in cardiac cells

D) The resting membrane potential of skeletal muscle is about 50mV

E) There are two types of K+ channels that produce repolarisation in cardiac cells

29. Regarding the action potential:

A) The outside of the membrane becomes positive during an action potential when depolarised

B) The speed of conduction is decreased in myelinated cells

C) The speed of conduction is increased in antidromic conduction

D) The speed of conduction is greater in A fibre types, compared with C fibre types

E) Phase I in cardiac muscle cells is caused by an influx of Na+

30. Insulin secretion is increased by:

A) Thiazide diuretics

B) Glucagon

C) Potassium depletion

D) Adrenaline

E) Somatostatin

31. During the cardiac cycle:

A) Ventricular systole starts with opening of the aortic valve

B) Rapid ejection occurs at the end of systole

C) Phase 3 corresponds to ventricular ejection

D) With a rate of 75bpm, diastole is 0.27 seconds

E) The V wave relates to rise in atrial pressure before the closure of the tricuspid valve

32. With regards to calcium regulation and metabolism:

A) 98% of calcium is reabsorbed in the proximal tubule

B) The transport of calcium out of the intestine into the circulation involves a calcium dependent ATPase

C) A decrease in plasma calcium level will decrease 1,25-dihydroxycholecalciferol level

D) Calcium absorption is increased by high levels of phosphates and oxalates

E) Distal tubule reabsorption is not regulated by parathyroid hormone

33. CO2 can increase respiration by:

A) Stimulating pulmonary stretch receptors

B) Stimulating central chemoreceptors

C) Inhibiting peripheral chemoreceptors

D) Stimulating J receptors in alveolar walls

E) Increasing CSF pH

34. With regards to cerebral blood flow:

A) Autoregulation is not a typical feature

B) It is increased with raised intracranial pressure

C) It is unaffected by sympathetic stimulation

D) It is maintained at normal flow limits with arterial pressures ranging from 35-160mmHg

E) It is maintained in times of increased intracranial pressure by the Cushing reflex

35. The vasomotor centre receives:

A) Excitatory input from the lungs

B) Excitatory and inhibitory inputs from the carotid chemoreceptors

C) Direct stimulation from the heart

D) Excitatory input from the kidneys

E) Inhibitory input from the pain pathways

36. Regarding the ventilation and perfusion of the lung:

A) The V/Q ratio is 1 at the level of the 6th rib

B) The shunt equation calculates the true shunt in the pulmonary circulation

C) The blood flow is normally higher than the ventilation for units with equal V/Q ratios

D) The PO2 at the apex of the lung is 40mmHg higher than at the base

E) In a normal person, considerable blood flow goes to units with V/Q ratios above 10

37. Physiological dead space:

A) Is equal to anatomical dead space minus alveolar dead space

B) Is equal to residual volume

C) Is equal to expiratory reserve volume plus alveolar dead space

D) Can be estimated using the Bohr Equation

E) Can be measured with the Fick method

38. Regarding surfactant:

A) It is increased in persons who smoke cigarettes

B) It is mostly comprised of neural lipids

C) It is helpful in preventing pulmonary oedema

D) It increases the surface tension in alveoli

E) It is produced by type 2 macrophages

39. Regarding gastric secretion:

A) 250ml is produced daily

B) Mucin aids autodigestion

C) H+ ions move passively from parietal cell into gastric lumen

D) Acid secretion is stimulated by histamine type 1 receptors

E) Normal gastric juice has a pH of 1 when fasting

40. Increased T4 and T3 levels:

A) Causes CSF protein to increase

B) Causes O2 consumption of the thyroid to increase

C) Are not caused by starvation

D) Suppresses formation of LDL receptors

E) Delays epiphyseal closure

41. In pulmonary capillary gas exchange:

A) Transfer of N2O is diffusion limited

B) Transfer of CO is flow limited

C) The diffusing capacity is proportional to the alveolar-capillary surface area

D) The diffusing capacity for oxygen decreases with exercise

E) Diffusion is inversely proportional to the partial pressure of gas

42. Renin secretion is inhibited by:

A) Prostaglandins

B) Diuretics

C) Cardiac failure

D) Cirrhosis

E) Increased afferent arteriolar pressure

43. Glucose reabsorption by the kidney:

A) Is independent of glucose load

B) Occurs in the distal convoluted tubule

C) Involves potassium reabsorption

D) Occurs through passive diffusion

E) Occurs through secondary active transport

44. Insulin:

A) Is synthesised in the Golgi apparatus of beta cells

B) Is released mostly in its proinsulin form

C) Has a half-life of 50 minutes

D) Binds to intracellular receptors

E) Is mostly degraded in the liver and kidneys

Answers Physiology MCQs

Ganong, Review of Medical Physiology 20th Edition (unless otherwise stated)

1 E Chapter 38

2 D 21st Edition, Page 69-75

3. E West, Respiratory Physiology, The Essential, 6th Edition, Page 65

4. C 21st Edition, Page 673-674

5. E West, Respiratory Physiology, The Essential, 6th Edition, Page 47

6. B 10th Edition, Page 609-612, 658-660

7. B Page 232, 704

8. C Page 685, 697

9. C Page 440-441

10. C Page 242

11. E 16th Edition, Page 517-519

12. D 6th Edition, Page 82-83

13. D Page 790

14. A Page 123-127

15. B Page 110-111

16. A Page 704-705

17. A Page 294-297

18. B 19th Edition, Page 623-624

19. D Page 569

20. B 18th Edition, Page 213-214

21. E 18th Edition, Page 661-662

22. D Page 571

23. D Page 589-591

24. B West, Respiratory Physiology, The Essential, Page 122

25. B Page 699

26. E Page 569-570

27. B Page 57

28. A Page 65, 75

29. D Page 55, 59, 76

30. B Page 335, table 19-6

31. C 21st Edition, Page 567-571

32. B Page 369-370

33. B West, Respiratory Physiology, The Essential, 6th Edition, Page 106-109

34. E Page 595-596

35. B Page 582, table 31-4

36. D West, Respiratory Physiology, The Essential, 6th Edition, Page 45-60

37. D Lecture notes Physiology, Bray, 4th Edition, Page 423

38. C

39. E Page 476-478

40. C Page 313-315

41. C Page 638-639

42. E 19th Edition, Page 437

43. E Page 686-687

44. E 19th Edition, Page 320

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