Question 1

Which of the following statements best distinguishes the endocrine system from the nervous system in terms of how they control body functions?

Accepted Answer

The endocrine system acts over long distances via hormones released into the blood.

Question 2

Which organelle is primarily responsible for the synthesis of steroid hormones?

Accepted Answer

Smooth endoplasmic reticulum

Question 3

Why do lipid-soluble hormones act on intracellular receptors, while water-soluble hormones act on receptors in the plasma membrane?

Accepted Answer

Lipid-soluble hormones can diffuse through the plasma membrane due to their hydrophobic nature.

Question 4

Place the following steps of the cyclic AMP signaling mechanism in the correct order, starting with the hormone binding to its receptor:

1. The membrane receptor activates by changing its shape after binding with a hormone.
2. The activated membrane receptor binds to and activates G protein.
3. Activated G protein activates (or inactivates) the effector enzyme adenylate cyclase.
4. Activated adenylate cyclase catalyzes reactions that convert ATP to cyclic AMP.
5. Cyclic AMP activates protein kinases that cause metabolic and structural changes.

Accepted Answer

1, 2, 3, 4, 5

Question 5

Which of the following refers to a cellular mechanism in which persistently low levels of a hormone cause its target cells to form additional receptors for that hormone?

Accepted Answer

Up-regulation

Question 6

Which of the following applies more to lipid-soluble hormones than to water-soluble hormones?

Accepted Answer

Longer half-life in blood

Question 7

Which hormone is labeled 'A' in the diagram showing the regulation of thyroid hormone secretion (from hypothalamus to anterior pituitary to thyroid gland to target cells)?

Accepted Answer

Thyrotropin-releasing hormone (TRH)

Question 8

Which hormone is labeled 'B' in the diagram showing the regulation of thyroid hormone secretion?

Accepted Answer

Thyroid-stimulating hormone (TSH)

Question 9

Which hormone is labeled 'C' in the diagram showing the regulation of thyroid hormone secretion?

Accepted Answer

Thyroid hormones (T3 and T4)

Question 10

Is the regulation of thyroid hormone secretion an example of a negative feedback or positive feedback mechanism? Explain your answer.

Accepted Answer

Negative feedback, because increased thyroid hormone inhibits TRH and TSH release.

Question 11

A patient presents with an enlarged, protruding thyroid gland (goiter) as shown in the image. Which of the following best explains why inadequate dietary iodine can lead to this condition?

Accepted Answer

Lack of iodine prevents synthesis of thyroid hormones, leading to increased TSH stimulation and thyroid gland growth.

Question 12

Which of the following is a major effect of thyroid hormone (T3 and T4) in the body?

Accepted Answer

Increases the rate of cellular metabolism

Question 13

Which type of disorder might be treated therapeutically with calcitonin?

Accepted Answer

Bone disorder

Question 14

What is the trigger for parathyroid hormone (PTH) release?

Accepted Answer

Low blood calcium levels

Question 15

Which layer of the adrenal gland produces aldosterone?

Accepted Answer

Zona glomerulosa

Question 16

Which of the following statements about the adrenal medulla is correct?

Accepted Answer

The adrenal medulla produces catecholamines that reinforce and prolong the 'fight-or-flight' response.

Question 17

Which of the following is a direct effect of growth hormone (GH)?

Accepted Answer

Increases blood levels of fatty acids

Question 18

Which of the following best describes a tropic hormone?

Accepted Answer

A hormone that stimulates the release of another hormone from an endocrine gland

Regulation of Thyroid Hormone Secretion: Hormonal Pathways and Feedback

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