aiims pg 2011 phy.pdf

7/28/2019 AIIMS PG 2011 PHY.pdf

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AIIMS PG 2011: PHYSIOLOGY

1. True regarding animals that are chronically exposed to cold?a. Increased sympathetic stimulationb. Increased vagal actionc. Increase insulin levels in blood.d. Decrease blood supply to adipose tissue

2. True about shunt vessels:a. Evenly distributed throughout the skin.b. Role in nutritionc. Play a role in thermoregulationd. No autonomic nervous regulation

3. Vasomotor centre of medulla is associated with:a. Acts with the cardiovagal centre to maintain BPb. Independent of corticohypothalamic inputs.c. Influenced by baroreceptors not chemoreceptors.d. Essentially silent in sleep.

4. Energy expenditure in resting state depends on:a. Lean body massb. Adipose tissuec. Resting heart rated. Exercise

5. The primary direct stimulus for excitation of centralchemoreceptors regulating ventilation is:

a. Increased H+b. Increased CO2c. Increased O2d. Decreased CO2

6. True regarding myocardial O2 demand?a. Inversly related to heart rateb. Has direct relation to external cardiac workc. Directly roportional to duration of systoled. Is negligible at rest


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7. Angiotensin 2 causes all of the following except:a. Stimulation of thristb. Aldosterone secretionc. Increased ADH secretiond. Vasodilation

8. Maximum postprandial motility is seen in:a. Ascending colonb. Transverse colonc. Descending colond. Sigmoid colon

9. CSF pressure is mainly regulated by:a. Rate of CSF formationb. Rate of CSF absorptionc. Cerebral blood flowd. Venous pressure

10.Which of the following statement is true?

a. Fluid coming from descending limb of Henle is

hypotonic.b. Descending limb of loop of Henle is permeable to

solutes.

c. If clearance of a substance is greater than GFR, then

tubular secretion must be present.

d. Clearance of a substance is always more than GFR if

there is tubular secretion.

11.Nitrogen narcosis is caused due to:a. Nitrogen inhibits dismutase enzyme.

b. Increase production of Nitrous Oxide.

c. Increased solubility of nitrogen in nerve cell membrane.

d. Decrease in oxygen free radicals.

ANSWERS AND EXPLANATIONS

1.c, Explanation: Insulin is an anabolic hormone. It helps to the entryof glucose into the cell that produces more amount of ATP which

helps to maintain the temperature inside their body.


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2.c,Explanation: Cutaneous blood vessels have a role in

thermoregulation. The nutritive function is performed by skincapillaries and not by the shunt vessels and they are under control of

Autonomous nervous system. The Cutaneous blood vessels are not

evenly distributed throughout the skin ( especially in fingers, ear

lobules, toes and nose).

3. a, Explanation: Neural regulation of BP is brought about 2

different centres located in medulla. They are:

Vasomotor centre: Controls the sympathetic outflow. Cardiovagal centre: Controls the parasympathetic outflow. They act together to control the BP. Here it should be noted

that vasomotor centre is located in RVLM (Rostral

ventrolateral medulla) and cardiovagal centre is located in the

nucleus ambiguous. The vasomotor centre receives inputs from

corticohypothalamic fibres.

It is tonically active and discharge rhythmically. It receives inputs from both barorecepters and chemorecepters.

4. a, Explanation: Energy expenditure is almost equal to the BMR,

that is the minimum energy expenditure for the body to exist. The

BMR is related to both body surface area and Lean body mass. Lean

body mass is the total mass of the body-the fat.

5.a, Explanation: The primary direct stimulus for central

chemorecepters is increased H+ concentration in the CSF and brain

interstitial fluid. The blood H+ ions are poorly permeable to the

blood brain barrier but highly permeable to Carbon di oxide. So CO2

is hydrated after entering and forms H+. These H+ ions directly

stimulate the central chemorecepters to regulate the ventilation.

6.b, Explanation: Myocardial oxygen demand has constantrelationship with cardiac work. Cardiac work is composed of

external and internal cardiac work. External cardiac work refers to

the work done during the ejection phase of the cardiac cycle. Internal

cardiac work refers to the work done during isovolumetric

contraction.

External cardiac work has a constant relationship with the oxygen

demand. It increases with increase in the external work done.


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7. d, Explanation: Angiotensin 2 is one of the most potent

vasoconstrictors known.

8. c, Explanation: The major postprandial motility is seen in the

proximal descending colon.

9.d, Explanation: The CSF pressure is mostly dependent on the

absorption of CSF. Arachnoid villi acts as valves and allows CSF to

flow into venous sinuses when CSF pressure is about 1.5 mm Hg

greater than pressure of blood in venous sinuses.

10.c, If clearance of a substance is greater than GFR, then tubular

secretion must be present. Example: PAH (para amino hippuric

acid).

11. c, Explanation: Nitrogen narcosis is an effect of the brain of

gaseous nitrogen that occurs in divers who go below 100 feet depth

of sea. It occurs due to laws of partial pressure. At greater depth ofthe sea, the pressure becomes high. At sea level, nitrogen has no

significant role on the body. But at high depth below the sea level,

nitrogen produces significant degree of narcosis. Nitrogen dissolves

in the fatty substances of neuronal membranes producing

nitrogen narcosis.

aiims pg 2011 phy.pdf

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