Question 1

Which of the following best describes the primary difference in signal transmission between the endocrine and nervous systems?

Accepted Answer

The endocrine system uses blood-borne hormones for slower, longer-lasting, and widespread effects, while the nervous system uses rapid, brief, and precisely targeted electrical/chemical signals.

Question 2

A patient is given a drug that is highly water-soluble and acts via membrane-bound receptors. Which of the following is the most likely mechanism for this drug's cellular action?

Accepted Answer

It binds to a membrane receptor, activating a G protein and triggering a second messenger cascade such as cAMP.

Question 3

Which hormone class is synthesized from cholesterol, is lipid-soluble, and typically has a long half-life in plasma?

Accepted Answer

Steroid hormones

Question 4

A person with liver failure is likely to experience which of the following regarding hormone activity?

Accepted Answer

Extended hormone half-life and elevated hormone activity due to impaired metabolic inactivation

Question 5

Which of the following best explains why only 'free' hormones can bind to target cell receptors?

Accepted Answer

Carrier proteins block the hormone's active site, preventing receptor interaction.

Question 6

Arrange the following steps of the cAMP second messenger pathway in the correct order:
1. Adenylyl cyclase converts ATP to cAMP
2. Water-soluble hormone binds to a membrane-bound G-protein coupled receptor
3. Activated G-protein stimulates adenylyl cyclase
4. cAMP activates protein kinase A, which phosphorylates cellular proteins

Accepted Answer

2 → 3 → 1 → 4

Question 7

Which feedback mechanism is primarily responsible for maintaining hormone levels near a physiological set point, and what is a classic example?

Accepted Answer

Negative feedback; thyroid hormone regulation

Question 8

A patient with chronic high insulin levels develops insulin resistance. Which cellular process best explains this phenomenon?

Accepted Answer

Down-regulation of insulin receptors, reducing cell sensitivity to insulin

Question 9

Which of the following scenarios best illustrates hormone antagonism?

Accepted Answer

Glucagon raising blood glucose while insulin lowers it

Question 10

A water-soluble hormone is released into the bloodstream. Which of the following statements is most accurate regarding its transport and action?

Accepted Answer

It dissolves freely in plasma and binds to membrane-bound receptors to initiate a second messenger cascade.

Question 11

Which of the following best describes the effect of signal amplification in second messenger cascades?

Accepted Answer

A single hormone molecule can trigger the activation of millions of intracellular enzymes.

Question 12

Which of the following is an example of a humoral stimulus for hormone release?

Accepted Answer

Low blood calcium triggering parathyroid hormone (PTH) release

Question 13

Which of the following best explains why steroid hormones generally have slower but longer-lasting effects compared to peptide hormones?

Accepted Answer

Steroid hormones act via direct gene activation, leading to new protein synthesis, while peptide hormones act via rapid second messenger cascades.

Question 14

Which of the following factors does NOT directly affect the net plasma concentration of a hormone?

Accepted Answer

Number of target cell receptors

Question 15

A researcher observes that hormone X must be present for hormone Y to exert its full effect on a target tissue. This is an example of which hormone interaction?

Accepted Answer

Permissiveness

Question 16

Which of the following best describes the role of the hypothalamus in endocrine signaling?

Accepted Answer

It integrates neural input and regulates the anterior pituitary via tropic hormones delivered through the hypophyseal portal system.

Question 17

Which of the following statements about hormone half-life is correct?

Accepted Answer

After three half-lives, 12.5% of the hormone remains in the blood.

Question 18

Which of the following is a correct sequence for the gene activation mechanism of a lipid-soluble hormone?

Accepted Answer

Hormone diffuses through membrane → binds intracellular receptor → hormone-receptor complex binds DNA → mRNA transcription

Question 19

Which of the following best explains why the nervous system can override endocrine homeostasis during acute stress?

Accepted Answer

Neural inputs can rapidly trigger hormone release (e.g., epinephrine) and suppress homeostatic hormones (e.g., insulin) to prioritize survival.

Fundamentals of Endocrine Signaling and Action

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