Sun10October0740PM 16

Which of the following is the single most important regulator of the basal metabolic rate (BMR)?

(Please select 1 option)

Adrenal medulla

Thyroid gland

Autonomic nervous system

Hypothalamus Correct

Anterior pituitary gland

Explanation

The hypothalamus is the primary controller of the basal metabolic rate by regulating the activity of the anterior pituitary and thyroid glands.

The hypothalamus secretes thyrotropin-releasing hormone (TRH) when it senses low levels of thyroid hormones. The anterior pituitary responds to TRH by secreting thyroid-stimulating hormone (TSH) that in turn stimulates the release of thyroid hormones (T3 and T4) from the thyroid gland. T3 and T4 increase the BMR. The hypothalamus and anterior pituitary gland are subject to feedback loops.

The basal metabolic rate (BMR) is the amount of energy expended per unit time during a period of rest. The units are expressed as calories/m2/hour and are corrected for age and sex under standard conditions of rest.

Factors which influence BMR include:

Exercise

Thyroid function

Catecholamine release/activity of the autonomic nervous system

Food (specific dynamic action)

Pregnancy

Age and sex (higher in children and males)

Pyrexia.

Normal BMR in an adult male is 40 cal/m2/hour. A rough approximation is BMR = 37- (age-20)/4.

Answer Statistics

1

6%

2

44%

3

8%

4

40%

5

4%

Times answered: 231