Question 1

Which of the following best explains why hydrophilic hormones, such as insulin, require membrane-bound receptors to exert their effects on target cells?

Accepted Answer

They are unable to cross the lipid bilayer of the cell membrane due to their water solubility.

Question 2

A patient is given a drug that causes upregulation of insulin receptors on muscle cells. What is the most likely physiological effect of this drug?

Accepted Answer

Increased sensitivity of muscle cells to insulin, leading to enhanced glucose uptake.

Question 3

Which of the following is a correct sequence for the hormone transport pathway from secretion to action?

Accepted Answer

Endocrine gland secretes hormone → hormone enters bloodstream → travels through heart and arteries → diffuses out of capillaries to reach target cells

Question 4

Which of the following hormones is most likely to bind to an intracellular receptor and directly influence gene transcription?

Accepted Answer

Cortisol

Question 5

A researcher observes that after repeated administration of a certain opioid drug, the number of opioid receptors on neurons decreases. This phenomenon is best described as:

Accepted Answer

Downregulation

Question 6

Which of the following best distinguishes the nervous system from the endocrine system in terms of signal transmission?

Accepted Answer

The nervous system uses electrical signals (action potentials) that are fast and short-lived, while the endocrine system uses chemical signals (hormones) that are slower and longer-lasting.

Question 7

Which of the following is an example of a secondary endocrine organ and the hormone it secretes?

Accepted Answer

Kidneys – Erythropoietin

Question 8

A hormone is found in the bloodstream bound to a carrier protein. Which statement best describes this hormone?

Accepted Answer

It is likely a hydrophobic hormone, such as a steroid or thyroid hormone, and is inactive while bound.

Question 9

Which of the following best describes paracrine signaling?

Accepted Answer

A hormone acts on nearby cells via interstitial fluid.

Question 10

Which of the following is a correct example of a neuroendocrine organ and its function?

Accepted Answer

Adrenal medulla – Secretes epinephrine and norepinephrine in response to sympathetic stimulation

Question 11

A patient with low blood calcium is found to have increased numbers of parathyroid hormone (PTH) receptors on bone cells. This is an example of:

Accepted Answer

Upregulation

Question 12

Which of the following best explains why even tiny concentrations of hydrophilic hormones can have large effects on target cells?

Accepted Answer

Second messenger cascades amplify the signal, so one hormone molecule can activate many intracellular messengers.

Question 13

Which of the following is NOT a typical action of hormones on target cells?

Accepted Answer

Directly generating action potentials in neurons

Question 14

Which hormone is correctly matched with its primary action?

Accepted Answer

Glucagon – Stimulates glycogen breakdown in the liver

Question 15

A hydrophobic hormone is most likely to:

Accepted Answer

Bind to an intracellular receptor and influence gene transcription

Question 16

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

Accepted Answer

It acts as a master regulator by secreting releasing and inhibiting hormones that control the pituitary gland.

Question 17

Which of the following is a correct statement about the duration and speed of action for the nervous and endocrine systems?

Accepted Answer

The nervous system acts very quickly (milliseconds) but its effects are short-lived, while the endocrine system acts more slowly (hours to weeks) but its effects are long-lasting.

Question 18

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

Accepted Answer

Autocrine signaling affects the same cell that secreted the hormone, while paracrine signaling affects nearby cells.

Question 19

A patient with chronically high levels of a hormone is found to have decreased responsiveness to that hormone. Which mechanism best explains this observation?

Accepted Answer

Downregulation of hormone receptors on target cells

Question 20

Which of the following is a correct example of a hormone and its transport in the blood?

Accepted Answer

Thyroid hormone ($T_4$) is transported bound to thyroxine-binding globulin.

Endocrine and Nervous Systems: Structure, Function, and Hormone Signaling

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