Q: A hydrophilic hormone binds to its receptor on the plasma membrane. Which sequence correctly describes the adenylate cyclase–cAMP second messenger pathway?

$$\text{Hormone} \rightarrow \text{Receptor} \rightarrow \text{G-protein} \rightarrow \text{Adenylate cyclase} \rightarrow \text{cAMP} \rightarrow \text{Protein kinase A} \rightarrow \text{Phosphorylation of proteins}$$

Question 1

Which of the following best explains why steroid hormones generally have longer half-lives in the bloodstream compared to peptide hormones?

Accepted Answer

Steroid hormones are hydrophobic and extensively bound to plasma proteins, which protects them from rapid degradation.

Question 2

A patient is diagnosed with a tumor that secretes hormones, leading to symptoms unrelated to the tissue of origin. This is an example of:

Accepted Answer

Paraneoplastic syndrome, where cancer cells act as secondary endocrine tissues.

Question 3

Which of the following best describes the pathway of a classic endocrine hormone from secretion to target cell action?

Accepted Answer

Endocrine cell → interstitial fluid → blood capillaries → veins → heart → arteries → capillaries → interstitial fluid → target-cell receptor

Question 4

A hydrophilic hormone binds to its receptor on the plasma membrane. Which sequence correctly describes the adenylate cyclase–cAMP second messenger pathway?

Accepted Answer

$$	ext{Hormone} ightarrow 	ext{Receptor} ightarrow 	ext{G-protein} ightarrow 	ext{Adenylate cyclase} ightarrow 	ext{cAMP} ightarrow 	ext{Protein kinase A} ightarrow 	ext{Phosphorylation of proteins}$$

Question 5

Which hormone class is most likely to bind to intracellular receptors and directly influence gene transcription?

Accepted Answer

Steroid hormones

Question 6

A researcher observes that a target cell increases its number of hormone receptors after exposure to low hormone levels. This process is called:

Accepted Answer

Upregulation

Question 7

Which of the following is an example of a humoral stimulus regulating hormone secretion?

Accepted Answer

Elevated blood glucose stimulating insulin release from the pancreas

Question 8

Which of the following best describes the difference between paracrine and autocrine signaling?

Accepted Answer

Paracrine signals affect nearby cells; autocrine signals affect the same cell that secreted them.

Question 9

Which of the following is NOT a primary endocrine organ?

Accepted Answer

Heart

Question 10

A patient is exposed to high levels of a hormone for an extended period. Which cellular response is most likely?

Accepted Answer

Downregulation of hormone-specific receptors

Question 11

Which of the following best illustrates a synergistic hormone interaction?

Accepted Answer

Two hormones act on the same target cell, producing a greater effect together than either alone.

Question 12

Which of the following statements about hormone transport is correct?

Accepted Answer

Hydrophilic hormones generally travel freely in plasma, while hydrophobic hormones are usually bound to plasma proteins.

Question 13

Which of the following is a direct effect of activating protein kinase A in a target cell?

Accepted Answer

Phosphorylation of specific proteins, altering their activity or shape

Question 14

A hydrophobic hormone enters a target cell and binds its receptor. What is the next step in its mechanism of action?

Accepted Answer

The hormone-receptor complex binds to hormone-response elements on DNA.

Question 15

Which of the following best describes negative feedback regulation of hormone secretion?

Accepted Answer

A deviation from normal is detected, hormone secretion changes to restore normal range, and secretion decreases as normal is restored.

Question 16

Which of the following is a correct statement about thyroid hormone?

Accepted Answer

It is derived from the amino acid tyrosine and is hydrophobic.

Question 17

Which of the following is an example of a neural stimulus for hormone secretion?

Accepted Answer

Sympathetic neurons stimulating the adrenal medulla to release epinephrine

Question 18

Which of the following best explains why only certain cells respond to a particular hormone?

Accepted Answer

Only cells with the appropriate receptor for the hormone can respond.

Question 19

Which of the following is NOT a possible effect of hormone action on a target cell?

Accepted Answer

Directly increasing the number of chromosomes in the cell

Question 20

A patient with a genetic mutation lacks functional G-proteins in target cells. Which hormone signaling pathway would be most directly impaired?

Accepted Answer

Hydrophilic hormone signaling via second-messenger systems such as cAMP

Overview of the Endocrine System: Structure, Function, and Regulation

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