Q: Which of the following equations best represents the second messenger mechanism used by water-soluble hormones?

$$\text{Hormone} + \text{Receptor} \rightarrow \text{G protein activation} \rightarrow \text{Adenylate cyclase} \rightarrow \text{cAMP production}$$

Question 1

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

Accepted Answer

Endocrine glands secrete hormones directly into the bloodstream, while exocrine glands secrete substances into ducts that lead to body surfaces or cavities.

Question 2

A patient presents with excessive thirst and urination, but their blood glucose levels are normal. Which endocrine disorder is most likely responsible?

Accepted Answer

Diabetes insipidus

Question 3

Which hormone is produced by the alpha cells of the islets of Langerhans, and what is its primary function?

Accepted Answer

Glucagon; increases blood glucose by stimulating glycogen breakdown in the liver

Question 4

Which of the following best explains why steroid hormones can pass through cell membranes, while peptide hormones cannot?

Accepted Answer

Steroid hormones are lipid-soluble, allowing them to diffuse through the phospholipid bilayer, whereas peptide hormones are water-soluble and require membrane receptors.

Question 5

A patient with Graves disease is likely to exhibit which of the following symptoms due to hypersecretion of thyroid hormones?

Accepted Answer

Increased metabolic rate, weight loss, and exophthalmos

Question 6

Which of the following equations best represents the second messenger mechanism used by water-soluble hormones?

Accepted Answer

$$	ext{Hormone} + 	ext{Receptor} ightarrow 	ext{G protein activation} ightarrow 	ext{Adenylate cyclase} ightarrow 	ext{cAMP production}$$

Question 7

Which hormone is responsible for lowering blood calcium levels, and what is its mechanism of action?

Accepted Answer

Calcitonin; inhibits osteoclast activity and increases calcium excretion by the kidneys

Question 8

A patient with Cushing syndrome is most likely to have which of the following laboratory findings?

Accepted Answer

Elevated cortisol levels, hyperglycemia, and hypertension

Question 9

Which of the following best describes the difference between diabetes mellitus type I and type II?

Accepted Answer

Type I is caused by autoimmune destruction of beta cells, leading to absolute insulin deficiency; Type II is caused by insulin resistance and relative insulin deficiency.

Question 10

Which of the following hormones is released from the posterior pituitary and is involved in water reabsorption in the kidneys?

Accepted Answer

Antidiuretic hormone (ADH)

Question 11

A patient with hyposecretion of parathyroid hormone (PTH) is most likely to experience which of the following?

Accepted Answer

Tetany due to decreased blood calcium levels

Question 12

Which of the following best describes the hypothalamo-hypophyseal portal system?

Accepted Answer

A network of blood vessels connecting the hypothalamus to the anterior pituitary, allowing regulatory hormones to reach target cells directly.

Question 13

Which of the following is an example of a synergistic effect in the endocrine system?

Accepted Answer

Glucagon and epinephrine both increase blood glucose levels more effectively together than alone.

Question 14

Which equation best represents the negative feedback regulation of thyroid hormone secretion?

Accepted Answer

$$	ext{TRH} ightarrow 	ext{TSH} ightarrow 	ext{T3/T4} ightarrow 	ext{Inhibition of TRH and TSH}$$

Question 15

A patient with acromegaly is most likely to have which of the following underlying causes?

Accepted Answer

Hypersecretion of growth hormone (GH) after epiphyseal plate closure

Question 16

Which hormone is primarily responsible for stimulating the development of secondary sexual characteristics in males?

Accepted Answer

Testosterone

Question 17

Which of the following best describes the effect of up-regulation of hormone receptors?

Accepted Answer

Increased sensitivity of target cells to a hormone due to increased receptor numbers

Question 18

Which of the following best describes the function of mineralocorticoids released by the adrenal cortex?

Accepted Answer

Regulate sodium and potassium balance by acting on the kidneys

Question 19

Which hormone is released in response to darkness and helps regulate circadian rhythms?

Accepted Answer

Melatonin

Question 20

A patient with Addison disease is most likely to have which of the following symptoms?

Accepted Answer

Fatigue, hypotension, and hyperpigmentation due to adrenal cortex hyposecretion

The Endocrine System: Structure, Function, and Disorders

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