Physiology solved MCQs

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1. Regarding equilibrium potential (mammalian spinal motor neurons)

a. The resting membrane potential is – 70 mV – identical to that of Ecl

B. Equilibrium potential of potassium is +90 mV

c. Increases in external sodium concentrations decrease the resting membrane potential

d. Equilibrium potential of sodium is –60 mV

e. Na+K+ ATPase pumps 2 sodium out of cell for every 3 potassium it pumps in

2. Regarding body composition

a. 18% body weight is protein / related substances

B. 15% body weight is interstitial fluid

c. 60% body weight is water

d. 5% body weight is plasma

e. All of the above are true

3. Regarding buffers in the body

a. Initial correction of pH disturbance is achieved by the kidneys

B. The phosphate buffer system is the predominant buffer in the blood

c. Bones contribute to buffering by taking up bicarbonate

d. Hb is an important buffer in the blood

e. All of the above are true

4. The size of the action potential is decreased by

a. Decreased extracellular calcium

B. Increased external sodium

c. Decreased internal sodium

d. Decreased internal potassium

e. Increased internal potassium

5. Regarding body fluid compartments

a. About 2/3 TBW is extracellular

B. ECF / intracellular fluid volume ratio is larger in infants than in adults

c. Plasma volume in a 70 kg male is approximately 5 litres

d. A 30 year old male has 40% water as a percentage of body weight

e. Transcellular fluid has a greater volume than intracellular fluids

6. Fick’s Law of Diffusion is dependent on all EXCEPT

a. The posture of the subject

B. The solubility of the gas

c. Thickness of membrane barrier

d. Molecular weight of the gas

e. Area of the membrane

7. Regarding movement across cell membranes

a. Exocytosis requires sodium and energy

B. Insulin reuptake is by receptor mediated endocytosis

c. Thyroid hormones decrease the activity of the NaK ATPase

d. Active transport of sodium is rarely coupled with other substances

e. NaK ATPase has a 1:1 coupling ratio

8. In regard to pH

a. pH of a solution is the log to base 10 of the reciprocal hydrogen ion concentration

B. Is the negative log of the concentration of hydrogen ions

c. For each pH unit less than 7 – the concentration of hydrogen ion is increased 10 fold

d. A pH of 7 is equal to a hydrogen ion concentration of 10-7 mmol/l

e. All of the above are true

9. Regarding heterotrimeric G proteins

a. GDP is bound to the B subunit

B. They are not serpentine receptors

c. The delta unit separates from the other subunits to bring about the biological effect

d. The intrinsic GTPase activity of the alpha subunit converts GTP to GDP

e. They span the membrane seven times

10. Which of the following is correct?

a. Chloride concentration in interstitial fluid is greater than in the plasma

B. Potassium concentration in interstitial fluid is greater than that in intracellular fluid

c. Sodium concentration in intracellular fluid is greater than in plasma

d. Protein concentration in plasma is greater than in intracellular fluid

e. Bicarbonate concentration in intracellular fluid is greater than in interstitial fluid

11. Regarding basic physiological measures – all of the following are true EXCEPT

a. Osmolarity is the number of osmoles / litre of solution

B. PH is the log to base 10 of the reciprocal of hydrogen ion concentration

c. Carbon has a molecular mass of 12 dalton

d. Osmolarity is measured by freezing point depression

e. One equivalent of sodium is 23 g/l

12. With regards to cell membrane potential

a. The Donnan effect relies on nondiffusible ions

B. The exterior of the cell is negative with respect to the interior

c. The membrane potential tends to push chloride out of the cell

d. It can be derived by measuring the chloride concentration and using the Nernst equation

e. Potassium leaks out against its concentration gradient

13. Regarding the comparison of ECF with CSF – all of the following are trueEXCEPT

a. CSF has less protein

B. CSF has lower osmolality

c. CSF has lower pH

d. CSF has more bicarbonate

e. CSF has lower specific gravity

14. Which of the following does NOT act via an intracellular receptor?

a. Cortisol

B. Thyroxine

c. ANP

d. Aldosterone

e. Retinoic acid

15. Regarding functional morphology of the cell

a. Tay Sachs disease is a cell membrane disorder

B. Actin is the most abundant protein in mammalian cells

c. Peroxisomes are 5 um in diameter

d. The assembly of microtubules in the cell cytoskeleton is facilitated by cold

e. Myosin 1 is present in skeletal muscle

chapter:   Cardiovascular

16. Regarding ECG changes, which is CORRECT?

a. hypernatraemia is associated with low voltage complexes

B. the first change in hyperkalaemia is prolongation of QRS

c. with hypokalaemia, the resting membrane potential decreases

d. in hyperkalaemia, the heart stops in systole

e. in hypercalcaemia, myocardial contractility is enhanced

17. Regarding jugular pressure waves:

a. the ‘v’ wave denotes the increased atrial pressure due to the bulging of the tricuspid valve during isovolumetric ventricular contraction

B. in tricuspid insufficiency, there is a giant ‘A’ wave with each ventricular systole

c. atrial premature beats produce an ‘A’ wave

d. the ‘v’ wave occurs during systole

e. a giant ‘C’ wave (‘cannon wave’) may be seen in complete heart block

18. What factor does not alter cardiac output?

a. standing up

B. sleeping

c. eating

d. exercising

e. pregnancy

19. What is the O2 consumption of a beating heart at rest?

a. 2ml/100g/min

B. 9ml/g/min

c. 2ml/g/min

d. 2L/100g/min

e. 9ml/100g/min

20. Regarding percentages of blood volume in the body:

a. the heart has 5%

B. the pulmonary circulation has the greatest percentage

c. the venous circulation has 35%

d. the aorta has 2%

e. capillaries have 20%

21. What is a biological action of endothelin?

a. dilates vascular smooth muscle

B. produces bronchodilation

c. increase GFR and renal blood flow

d. evokes positive inotropic and chronotropic effects on myocardium

e. inhibits gluconeogenesis

22. What inhibits gene transcription for endothelin-1 secretion:

a. nitric oxide

B. angiotensin II

c. insulin

d. growth factors

e. catecholamines

23. Regarding NO synthase:

a. it synthesises nitrous oxide from arginine

B. there are 2 isoforms

c. it is inactivated by haemoglobin

d. NOS-1 is activated by cytokines

e. NOS-2 is in endothelial cells

24. What factor dilates the arterioles?

a. decreased local temperature

B. myogenic theory of autoregulation

c. angiotensin II

d. increased discharge of noradrenergic vasomotor nerve

e. histamine

25. Which is NOT a baroreceptor site?

a. right atria at the entrance of SVC and IVC

B. aortic arch

c. left atria at the entrance of the pulmonary veins

d. pulmonary circulation

e. carotid body

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