Question 1

Which of the following best describes the mechanism by which oxytocin stimulates uterine contractions during childbirth?

Accepted Answer

It mobilizes Ca$$^{2+}$$ through a PIP$$_2-Ca$^{2+}$$ second-messenger system in uterine smooth muscle cells.

Question 2

A patient presents with excessive thirst, frequent urination, and dilute urine. Laboratory tests reveal low levels of antidiuretic hormone (ADH). What is the most likely diagnosis?

Accepted Answer

Diabetes insipidus

Question 3

Which of the following steps is NOT involved in the synthesis of thyroid hormone (TH)?

Accepted Answer

T$$_3$$ and T$$_4$$ are stored in the adrenal cortex until needed.

Question 4

A patient with Graves’ disease is likely to exhibit which of the following symptoms?

Accepted Answer

High metabolic rate, weight loss, and exophthalmos

Question 5

Which hormone is produced by the parafollicular (C) cells of the thyroid gland and what is its primary function?

Accepted Answer

Calcitonin; lowers blood calcium by inhibiting osteoclast activity

Question 6

Which of the following best explains why removal of the thyroid gland does not significantly affect calcium homeostasis in adults?

Accepted Answer

Parathyroid hormone (PTH) is the primary regulator of blood calcium, not calcitonin.

Question 7

A tumor in the zona glomerulosa of the adrenal cortex would most likely result in which of the following clinical findings?

Accepted Answer

Hypertension and edema due to excessive Na$$^+$$ retention

Question 8

Which hormone is primarily responsible for the long-term stress response that includes retention of sodium and water by the kidneys?

Accepted Answer

Aldosterone

Question 9

A patient with Cushing’s syndrome is likely to exhibit all of the following EXCEPT:

Accepted Answer

Hypoglycemia and severe dehydration

Question 10

Which of the following best describes the effect of insulin on target cells?

Accepted Answer

Enhances membrane transport of glucose into fat and muscle cells

Question 11

Which hormone is secreted by the heart and acts to reduce blood pressure, blood volume, and blood Na$$^+$$ concentration?

Accepted Answer

Atrial natriuretic peptide (ANP)

Question 12

A patient with hypoparathyroidism following thyroid surgery is at greatest risk for which of the following complications?

Accepted Answer

Tetany, respiratory paralysis, and death

Question 13

Which of the following is a direct effect of glucagon on the liver?

Accepted Answer

Stimulates glycogenolysis and gluconeogenesis, increasing blood glucose

Question 14

Which hormone is responsible for stimulating the production of red blood cells in response to hypoxia?

Accepted Answer

Erythropoietin

Question 15

Which of the following best explains why older women are more vulnerable to osteoporosis?

Accepted Answer

Estrogen deficiency increases the bone-demineralizing effects of parathyroid hormone (PTH).

Question 16

Which of the following is a function of melatonin secreted by the pineal gland?

Accepted Answer

Regulation of day/night cycles and physiological rhythms

Question 17

Which hormone is released in response to decreased blood pressure and initiates the renin-angiotensin-aldosterone mechanism?

Accepted Answer

Renin

Question 18

Which of the following best describes the negative feedback regulation of thyroid hormone (TH) release?

Accepted Answer

Rising TH levels inhibit the release of TSH from the anterior pituitary.

Question 19

Which hormone is produced by pancreatic beta ($$\beta) $$cells and what is its primary effect?

Accepted Answer

Insulin; lowers blood glucose by enhancing cellular uptake

Question 20

A patient with Addison’s disease is likely to present with which of the following laboratory findings?

Accepted Answer

Decreased blood glucose and sodium levels

The Endocrine System: Structure, Function, and Regulation

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