Q: Which of the following equations best represents the signal amplification that occurs in a second messenger system?

$$1 \text{ hormone} \rightarrow 1 \text{ receptor} \rightarrow n \text{ G proteins} \rightarrow n^2$ \text{ enzymes} \rightarrow n^3$ \text{ second messengers}$$

Question 1

Which of the following best describes the main difference between the nervous and endocrine systems in terms of how they affect target cells?

Accepted Answer

The nervous system uses neurotransmitters to directly affect target cells, while the endocrine system uses hormones to indirectly affect target cells.

Question 2

A patient is given a synthetic hydrophilic hormone. Which of the following is most likely to occur at the target cell?

Accepted Answer

The hormone will bind to an integral membrane receptor and activate a second messenger system.

Question 3

Which of the following is an example of a paracrine signal?

Accepted Answer

A chemical secreted by a cell that affects nearby but different types of cells.

Question 4

Which of the following best explains why hydrophobic hormones generally have longer-lasting effects than hydrophilic hormones?

Accepted Answer

Hydrophobic hormones are bound to plasma protein carriers, making them less susceptible to breakdown.

Question 5

A researcher observes that prolonged exposure to a certain hormone leads to a decrease in the number of its receptors on the target cell. This process is known as:

Accepted Answer

Down-regulation

Question 6

Which of the following is true regarding the mechanism of action for steroid hormones?

Accepted Answer

They bind to cytosolic or nuclear receptors and often alter gene transcription.

Question 7

A sudden increase in blood glucose levels stimulates the release of insulin from the pancreas. This is an example of which type of stimulus?

Accepted Answer

Humoral stimulus

Question 8

Which of the following equations best represents the signal amplification that occurs in a second messenger system?

Accepted Answer

$$1 	ext{ hormone} ightarrow 1 	ext{ receptor} ightarrow n 	ext{ G proteins} ightarrow n^2$ 	ext{ enzymes} ightarrow n^3$ 	ext{ second messengers}$$

Question 9

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

Accepted Answer

Directly generating action potentials in neurons

Question 10

A patient with a tumor in an endocrine gland is found to have abnormally high levels of a hormone and a decrease in the number of its receptors on target cells. Which feedback mechanism is most likely responsible for this change in receptor number?

Accepted Answer

Down-regulation

Question 11

Which of the following best describes the transport of hydrophilic hormones in the blood?

Accepted Answer

They travel freely dissolved in the plasma.

Question 12

Which of the following is an example of a hormone acting as an autocrine signal?

Accepted Answer

A hormone secreted by a cell that affects the same cell that secreted it.

Question 13

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 circulate in the blood and can affect target cells for a longer period.

Question 14

A patient is given a drug that blocks G protein activation in target cells. Which hormone action would be most affected?

Accepted Answer

Hydrophilic hormones using second messenger systems

Question 15

Which of the following is a correct statement about hormone-receptor interactions?

Accepted Answer

Hydrophobic hormones can bind to receptors in the cytosol or nucleus.

Question 16

Which of the following best describes a synergistic hormone interaction?

Accepted Answer

Two hormones produce a greater response together than each acting alone.

Question 17

A patient is experiencing rapid removal of a hormone from their bloodstream. Which type of hormone is most likely responsible?

Accepted Answer

Hydrophilic hormone traveling freely in the blood

Question 18

Which of the following is a correct sequence for the pathway of hormone secretion and action?

Accepted Answer

Endocrine cell $$\rightarrow$$ interstitial fluid $$\rightarrow$$ blood $$\rightarrow$$ target cell receptor

Question 19

Which of the following is most likely to occur if a target cell is exposed to abnormally low levels of a hormone for an extended period?

Accepted Answer

Up-regulation of receptors

Question 20

Which of the following best describes the chemical nature of most amino acid-based hormones?

Accepted Answer

They are hydrophilic and range from single amino acids to peptides.

Endocrine System: Hormones, Signaling, and Regulation 16

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