Q: Which of the following is a correct sequence for the hypothalamic-pituitary-thyroid axis?

$$\text{TRH} \rightarrow \text{TSH} \rightarrow \text{TH}$$

Question 1

Which of the following best explains why steroid hormones can directly activate gene expression in target cells, while peptide hormones cannot?

Accepted Answer

Steroid hormones are lipid-soluble and can cross the plasma membrane to bind intracellular receptors that act as transcription factors.

Question 2

A patient presents with symptoms of excessive thirst, frequent urination, and high blood glucose levels. Laboratory tests reveal low insulin levels. Which hormone is most likely deficient, and what is the primary effect of this deficiency?

Accepted Answer

Insulin; increased blood glucose due to decreased cellular glucose uptake.

Question 3

Which of the following is an example of a hormone released in response to humoral stimuli?

Accepted Answer

Parathyroid hormone (PTH) released when blood calcium levels are low.

Question 4

A researcher is studying a hormone that is synthesized from cholesterol, travels in the blood bound to plasma proteins, and acts on intracellular receptors. Which hormone is most likely being studied?

Accepted Answer

Cortisol

Question 5

Which of the following best describes the mechanism of action for water-soluble hormones?

Accepted Answer

They bind to plasma membrane receptors and activate second messenger systems such as cAMP.

Question 6

A patient with a tumor in the anterior pituitary is found to have elevated levels of ACTH. Which of the following is a likely consequence?

Accepted Answer

Increased cortisol production, leading to symptoms of Cushing's syndrome.

Question 7

Which of the following scenarios best illustrates the concept of hormone antagonism?

Accepted Answer

Insulin and glucagon have opposite effects on blood glucose levels.

Question 8

A person is exposed to a chemical that blocks the action of phosphodiesterase in their cells. What is the most likely effect on hormone signaling via the cAMP pathway?

Accepted Answer

Increased cAMP levels, leading to prolonged activation of protein kinases.

Question 9

Which of the following best explains why the effects of the endocrine system are generally longer-lasting than those of the nervous system?

Accepted Answer

Hormones travel through the blood and can affect many target cells, and their effects persist even after the hormone is degraded.

Question 10

A patient with a deficiency in antidiuretic hormone (ADH) would most likely experience which of the following symptoms?

Accepted Answer

Large volumes of dilute urine and intense thirst.

Question 11

Which of the following is a correct sequence for the hypothalamic-pituitary-thyroid axis?

Accepted Answer

$$	ext{TRH} ightarrow 	ext{TSH} ightarrow 	ext{TH}$$

Question 12

Which hormone is released by the adrenal medulla and is responsible for increasing heart rate and blood glucose during acute stress?

Accepted Answer

Epinephrine

Question 13

A patient has a mutation that causes their target cells to upregulate hormone receptors. What is the most likely effect on the sensitivity of these cells to the hormone?

Accepted Answer

Increased sensitivity, requiring less hormone to achieve the same effect.

Question 14

Which of the following best describes the role of parathyroid hormone (PTH) in calcium homeostasis?

Accepted Answer

PTH stimulates osteoclasts to release calcium from bone and increases calcium reabsorption in the kidneys.

Question 15

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

Accepted Answer

Promotion of protein synthesis and use of fats for fuel.

Question 16

A patient is given a drug that mimics the action of atrial natriuretic peptide (ANP). Which of the following effects would you expect?

Accepted Answer

Decreased blood pressure due to increased sodium excretion.

Question 17

Which of the following best explains why removal of the thyroid gland does not significantly affect calcium homeostasis in adults?

Accepted Answer

Parathyroid hormone (PTH) is the main hormone regulating calcium, and the parathyroid glands remain intact.

Question 18

Which of the following is a correct example of a permissive hormone interaction?

Accepted Answer

Thyroid hormone increases the number of adrenergic receptors, enhancing the effect of epinephrine.

Question 19

A patient with chronic stress has elevated levels of cortisol. Which of the following is a likely consequence of this condition?

Accepted Answer

Suppressed immune response and increased gluconeogenesis.

Question 20

Which of the following best describes the role of the pineal gland?

Accepted Answer

It produces melatonin, which regulates circadian rhythms and sleep cycles.

Chapter 16: The Endocrine System – Structure, Function, and Hormone Mechanisms

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