1. A patient with diabetes mellitus has a high blood glucose level. Which

of the following is an example of negative feedback that occurs in

response to this condition?

a) The pancreas secretes more insulin to lower the blood glucose level.

b) The liver converts more glucose into glycogen for storage.

c) The kidneys excrete more glucose in the urine.

d) The cells take up more glucose from the blood.

Answer: a) The pancreas secretes more insulin to lower the blood glucose

level. Rationale: Negative feedback is a mechanism that restores a

deviation from a set point to normal. In this case, the high blood glucose

level is the deviation and the normal range is the set point. The pancreas

secretes insulin, a hormone that lowers the blood glucose level by

stimulating the cells to take up glucose from the blood and the liver to

convert glucose into glycogen. This is an example of negative feedback

because the action of insulin reduces the deviation from the set point.

2. A patient with hypothyroidism has a low metabolic rate and feels cold

most of the time. Which of the following is an example of positive

feedback that occurs in response to this condition?

a) The hypothalamus releases more thyrotropin-releasing hormone (TRH)

to stimulate the pituitary gland.

b) The pituitary gland releases more thyroid-stimulating hormone (TSH)

to stimulate the thyroid gland.

c) The thyroid gland releases more thyroid hormones (T3 and T4) to

increase the metabolic rate.

d) The body shivers to generate heat and maintain the body temperature.

Answer: d) The body shivers to generate heat and maintain the body

temperature. Rationale: Positive feedback is a mechanism that amplifies a

deviation from a set point rather than restoring it to normal. In this case,

the low metabolic rate and low body temperature are the deviations and

the normal range is the set point. The body shivers, which is a muscular

activity that generates heat and increases the metabolic rate. This is an

example of positive feedback because the action of shivering increases the

deviation from the set point.

3. A patient with hypertension has a high blood pressure. Which of the

following is an example of negative feedback that occurs in response to