Question 1

Which of the following best describes the concept of 'down-regulation' in hormone activity?

Accepted Answer

A decrease in the number of hormone receptors on target cells in response to high hormone levels.

Question 2

A patient is diagnosed with a condition that causes excessive secretion of a particular hormone. Which cellular response would most likely occur in the target tissue?

Accepted Answer

Down-regulation of hormone receptors to prevent overstimulation.

Question 3

Which statement accurately explains the role of glycoprotein receptors in hormone activity?

Accepted Answer

Glycoprotein receptors allow hormones to affect only specific target tissues.

Question 4

If the body experiences a significant reduction in the production of a hormone, what is the most likely cellular response?

Accepted Answer

Up-regulation of receptors to increase sensitivity to the hormone.

Question 5

Which of the following scenarios best illustrates up-regulation?

Accepted Answer

A person with low thyroid hormone levels develops more thyroid hormone receptors on target cells.

Question 6

Which equation best represents the relationship between hormone concentration ($$[H]) $$and receptor number ($$R) $$during down-regulation?

Accepted Answer

$$R \propto \frac{1}{[H]}$$

Question 7

A researcher observes that the number of hormone receptors on a cell membrane fluctuates over time. What is the most likely explanation for this phenomenon?

Accepted Answer

Receptors are constantly synthesized and broken down in response to changing hormone levels.

Question 8

Which of the following is a direct consequence of up-regulation in hormone activity?

Accepted Answer

Increased sensitivity of target cells to the hormone.

Question 9

A patient with an endocrine disorder is found to have abnormally low numbers of hormone receptors on target cells, despite normal hormone levels. Which process is most likely impaired?

Accepted Answer

Up-regulation of receptors.

Question 10

Which of the following best explains why hormones only affect specific target tissues?

Accepted Answer

Only target tissues possess specific glycoprotein receptors for the hormone.

Question 11

A patient is treated with a drug that blocks glycoprotein receptors for a specific hormone. What is the most likely physiological effect?

Accepted Answer

The hormone will have no effect on the target tissue.

Question 12

Which process is most likely to occur if a hormone is chronically under-produced?

Accepted Answer

Up-regulation of receptors to increase tissue sensitivity.

Question 13

In a feedback loop, what is the expected effect on receptor numbers if hormone levels remain elevated for an extended period?

Accepted Answer

Receptor numbers will decrease due to down-regulation.

Question 14

Which of the following is NOT a function of glycoprotein hormone receptors?

Accepted Answer

Synthesizing hormones within the cell.

Question 15

A cell exposed to high concentrations of a hormone for a prolonged period is likely to:

Accepted Answer

Decrease the number of hormone receptors (down-regulation).

Question 16

Which of the following best describes the relationship between hormone concentration and receptor availability in target tissues?

Accepted Answer

Low hormone concentration leads to up-regulation of receptors.

Question 17

A patient with Addison's disease has low cortisol levels. What adaptation would you expect in the target tissues?

Accepted Answer

Up-regulation of cortisol receptors.

Question 18

Which of the following equations best models the effect of up-regulation on receptor number ($$R) $$when hormone concentration ($$[H]) $$decreases?

Accepted Answer

$$R \propto \frac{1}{[H]}$$

Question 19

Which of the following is a real-world example of down-regulation?

Accepted Answer

Insulin resistance in type 2 diabetes due to chronically high insulin levels.

Hormone Activity and Receptor Regulation in the Endocrine System

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