Question 1

Which of the following best describes the main difference between the nervous system and the endocrine system in terms of response duration and signaling mechanism?

Accepted Answer

The nervous system initiates responses rapidly with short-duration effects using neurotransmitters, while the endocrine system initiates responses slowly with long-duration effects using hormones.

Question 2

A patient presents with persistently low levels of a particular hormone. Which cellular adaptation is most likely to occur in the target cells?

Accepted Answer

Up-regulation of receptors for that hormone.

Question 3

Which of the following hormones is synthesized from cholesterol and is lipid-soluble, allowing it to cross the plasma membrane and bind to intracellular receptors?

Accepted Answer

Cortisol

Question 4

Amino acid-based hormones (except thyroid hormone) typically exert their effects through which of the following mechanisms?

Accepted Answer

Second-messenger systems involving membrane receptors

Question 5

Which of the following equations correctly represents the conversion of ATP to cyclic AMP (cAMP) in the cAMP signaling mechanism?

Accepted Answer

$$ATP \rightarrow cAMP + PP_i$$

Question 6

Which hormone is secreted in response to declining blood calcium levels and acts to increase blood calcium by stimulating osteoclasts, enhancing kidney reabsorption, and promoting intestinal absorption?

Accepted Answer

Parathyroid hormone (PTH)

Question 7

A patient with hypersecretion of aldosterone would most likely exhibit which of the following symptoms?

Accepted Answer

Increased blood sodium and decreased blood potassium

Question 8

Which of the following best explains why thyroid hormone (TH) is considered permissive for epinephrine and norepinephrine?

Accepted Answer

TH increases the number of adrenergic receptors in blood vessels, allowing normal blood pressure regulation.

Question 9

Which of the following is a correct sequence for the activation of the cAMP second messenger system by an amino acid-based hormone?

Accepted Answer

Hormone binds receptor → G protein activated → Adenylate cyclase activated → ATP converted to cAMP → Protein kinases activated

Question 10

Which of the following best describes the role of melatonin secreted by the pineal gland?

Accepted Answer

Regulates biological rhythms and acts as an antioxidant

Question 11

A patient is experiencing symptoms of long-term stress. Which hormone is most likely elevated, and what is its primary metabolic effect?

Accepted Answer

Cortisol; increases blood glucose by promoting gluconeogenesis and protein breakdown

Question 12

Which of the following best describes the feedback mechanism regulating blood calcium levels involving PTH?

Accepted Answer

Negative feedback: rising blood calcium inhibits PTH secretion

Question 13

Which hormone is secreted by the heart in response to high blood volume and pressure, and what is its effect?

Accepted Answer

Atrial natriuretic peptide (ANP); increases sodium excretion and decreases blood pressure

Question 14

Which of the following is NOT a function of insulin?

Accepted Answer

Promoting gluconeogenesis in the liver

Question 15

Which of the following equations represents the relationship between blood hormone concentration, rate of release, and rate of removal?

Accepted Answer

$$[Hormone] = \frac{Rate\ of\ Release}{Rate\ of\ Removal}$$

Question 16

Which of the following best explains why steroid hormones typically have longer-lasting effects than amino acid-based hormones?

Accepted Answer

Steroid hormones bind to plasma proteins, prolonging their half-life in circulation.

Question 17

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

Accepted Answer

Declining blood calcium levels stimulate parathyroid glands to secrete PTH.

Question 18

Which of the following hormones is produced by parafollicular cells of the thyroid gland and acts to lower blood calcium levels?

Accepted Answer

Calcitonin

Question 19

Which of the following best describes the effect of glucagon on blood glucose levels?

Accepted Answer

Increases blood glucose by stimulating glycogenolysis and gluconeogenesis in the liver

The Endocrine System: Structure, Function, and Comparison with the Nervous System

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