Question 1

Which of the following best describes the difference between endocrine and exocrine glands?

Accepted Answer

Endocrine glands secrete hormones directly into body fluids, while exocrine glands secrete substances into ducts.

Question 2

A hormone binds to a membrane receptor and activates a G protein. Which enzyme is then activated to produce the second messenger cAMP?

Accepted Answer

Adenylate cyclase

Question 3

Which of the following is TRUE regarding steroid hormones?

Accepted Answer

They are synthesized from cholesterol and can pass through the plasma membrane.

Question 4

Which organ is considered the 'master gland' of the endocrine system?

Accepted Answer

Pituitary gland

Question 5

A patient has low blood calcium levels. Which hormone is most likely to be released to correct this imbalance, and what is its primary function?

Accepted Answer

Parathyroid hormone (PTH); increases blood calcium

Question 6

Which of the following is a correct sequence for the mechanism of action of a steroid hormone?

Accepted Answer

Steroid hormone diffuses through plasma membrane, binds to intracellular receptor, hormone-receptor complex enters nucleus, binds DNA, initiates transcription of mRNA.

Question 7

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

Accepted Answer

Low blood calcium triggering parathyroid hormone release

Question 8

Which statement about amino acid-based hormones is CORRECT?

Accepted Answer

They are mostly water soluble and circulate freely in the bloodstream.

Question 9

Which of the following is a paracrine signaling example?

Accepted Answer

Histamine released at a site affecting nearby cells

Question 10

Which of the following is NOT a major function of the endocrine system?

Accepted Answer

Initiation of voluntary muscle contraction

Question 11

Which of the following best describes autocrine signaling?

Accepted Answer

A cell releases a chemical messenger that affects itself.

Question 12

Which of the following equations correctly represents the conversion of ATP to cAMP by adenylate cyclase?

Accepted Answer

$$ATP \rightarrow cAMP + PP_i$$

Question 13

Which hormone is released by the adrenal medulla in response to neural stimuli during the 'fight or flight' response?

Accepted Answer

Epinephrine

Question 14

Which of the following is TRUE about protein hormones?

Accepted Answer

They must bind to specific protein receptors in the plasma membrane to take effect.

Question 15

Which of the following is NOT an endocrine-only organ?

Accepted Answer

Pancreas

Question 16

Which of the following is a common effect of hormone action?

Accepted Answer

Activating or deactivating enzymes

Question 17

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

Accepted Answer

It controls the pituitary gland, integrating nervous and endocrine functions.

Question 18

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

Accepted Answer

Steroid hormones bind to intracellular receptors, while protein hormones bind to membrane receptors.

Question 19

Which of the following is a correct example of negative feedback in hormone regulation?

Accepted Answer

Low blood calcium levels stimulate parathyroid hormone release, which increases blood calcium and inhibits further hormone release.

Question 20

Which of the following is the correct order of events for the action of a water-soluble hormone using cAMP as a second messenger?

Accepted Answer

Hormone binds to membrane receptor, activates G protein, adenylate cyclase converts ATP to cAMP, cAMP activates protein kinases.

Endocrine System: Structure, Function, and Hormone Mechanisms

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