MBBS Physiology

Question 1

What is the normal resting membrane potential of a cardiac ventricular myocyte?

Accepted Answer

-90 mV

Answer

The resting membrane potential of ventricular myocytes is approximately -90 mV, maintained primarily by K+ leak channels.

Question 2

Which of the following shifts the oxygen-hemoglobin dissociation curve to the right?

Accepted Answer

Increased 2,3-DPG

Answer

Increased 2,3-DPG reduces hemoglobin's affinity for oxygen, shifting the curve to the right and facilitating oxygen unloading to tissues.

Question 3

The Frank-Starling mechanism of the heart states that:

Accepted Answer

Stroke volume increases with increased end-diastolic volume

Answer

The Frank-Starling mechanism states that stroke volume increases as end-diastolic volume increases, up to a physiological limit.

Question 4

Which hormone is responsible for the long-loop negative feedback on the hypothalamo-pituitary axis in thyroid regulation?

Accepted Answer

T3 and T4

Answer

T3 and T4 exert negative feedback on both the pituitary (inhibiting TSH) and hypothalamus (inhibiting TRH) to regulate their own production.

Question 5

What is the GFR (glomerular filtration rate) in a healthy adult?

Accepted Answer

125 mL/min

Answer

The normal GFR in a healthy adult is approximately 125 mL/min (180 L/day), with approximately 99% of the filtrate reabsorbed.

MBBS - Bachelor of Medicine and Bachelor of Surgery Practice Test