When a skeletal muscle with an intact nerve supply is stretched, the muscle contracts and the tone increases. The following explanations are offered for this observation:

A. Golgi tendon organ was stimulated by the stretching of the muscle.

B. γ-motor neurons were excited by the stimulated afferent nerve fibres from the stretched muscle.

C. Muscle spindle was stimulated by stretching of muscle.

D. α-motor neurons were excited by the stimulated afferent nerve fibres from the stretched muscle.

Which of the combination is correct?

• A and B

• B and C

• C and D

• A and D

Upon prolonged illumination, activated rhodopsin does not activate transducer, hence the vision is impaired. This could be because of the following explanations:

A. Most of the activated rhodopsin gets phosphorylated and is unable to activate transducin.

B. Most of the activated rhodopsin gets phosphorylated and is unable to activate transducin.

C. Arrestin further interacts with phosphorylated rhodopsin.

D. Arrestin further interacts with dephosphorylated rhodopsin.

Which of the above combinations is correct?

• A and C

• B and D

• A and D

• B and C

At 17 years, a 7 feet tall human was diagnosed with gigantism caused by pituitary tumor. The condition was surgically corrected by removal of the person's pituitary gland. Doctors advised hormonal therapy. The possible hormonal therapies that would be required for survival are

A. Thyroid hormone

B. Glucocorticoids

C. Glucagon

D. Growth hormone

E. Insulin

Which of the following combination can be used?

• A and B only

• B and D only

• A, B and D

• A, C and E

Given below are few statements with reference to blood clot formation which results from triggered chain of reactions:

A. Conversion of fibrinogen to fibrin.

B. Activation of factor XIII, which stabilizes fibrin mesh work.

C. Activation of factor XII, which promotes plasmin activation.

D. Enhancement of platelet aggregation.

Which one of the following combination of statements is correct with reference to roles of thrombin in hemostasis?

• B, C and D

• A, B and D

• A, C and D

• A, B and C

The heart rate shows variation during respiratory rhythm in most human subjects. Which one of the following statements describing the changes in heart rate during respiratory phases is true?

• The heart rate is accelerated during expiration, but no change occurs during inspiration.

• The heart rate is accelerated during inspiration and decelerated during expiration.

• The heart rate is accelerated during expiration and decelerated during inspiration.

• The heart rate is accelerated during inspiration and no change occurs during expiration.

66.

When a nerve fiber is stimulated with increasing strength of the stimulus, the action potential fails of stimulus, the action potential fails to generate even though the threshold level may be passed. The following statements may explain this accommodation of nerve fiber:

A. The critical number of open sodium channels required to trigger the action potential may never be attained due to slow depolarization.

B. Potassium channels open in response to slow depolarization, which makes the nerve fiber refractory to depolarization.

C. The low threshold sodium channels remain open, which increases the threshold of firing of action potential.

D. The efflux of sodium and influx of potassium due to operation of Na⁺, K⁺ - ATPase oppose the depolarization.

Which one of the following is correct?

• A only

• A and B

• C only

• C and D

Different frequencies of sound were presented on the ear and the movement of the basilar membrane was experimentally determined. The characteristics of the movement of the basilar membrane after presentation of 100 Hz sound are described in the following statements:

A. The base of basilar membrane showed resonance.

B. The apex of basilar membrane showed resonance.

C. A wave traveled from the base to apex of basilar membrane but the maximum displacement was noted near the ape.

D. A wave traveled from the base to apex of basilar membrane but the maximum displacement was noted near the base.

Which one of the following is correct?

• A and C

• B and D

• C only

• D only

The changes in left ventricular stroke work (LVSW) according to the different left ventricular end-diastolic pressures (LVEDP, which indicates the initial myocardial fiber length) in a dog, under control conditions, were recorded, which follows Starling's law of the heart. This LVSW-LVEDP relationship was investigated in the same dog after constant infusion of norepinephrine, and these two data sets were plotted. Which one of the following graphs correctly represents the results obtained?

Which one of the following functions is NOT served by the plasma proteins?

• Blood clotting

• O₂ transport

• Hormone binding and transport

• Buffering capacity of blood

Production of excessive amount of corticotrophin (ACTH) occurs in which one of the following:

• Grave's disease

• Cushing's syndrome

• Grieg's syndrome

• Alport's syndrome