Question 1

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

Accepted Answer

Paracrine signaling acts on neighboring cells within the same tissue, while endocrine signaling involves hormones released into the bloodstream to affect distant organs.

Question 2

A patient presents with symptoms of rapid weight loss, heat intolerance, and increased heart rate. Blood tests reveal elevated levels of T3 and T4, but low TSH. Which of the following best explains these findings?

Accepted Answer

Primary hyperthyroidism due to thyroid gland overactivity, leading to negative feedback suppression of TSH.

Question 3

Which hormone is synthesized in the zona glomerulosa of the adrenal cortex and what is its primary function?

Accepted Answer

Aldosterone; promotes sodium reabsorption in the kidneys.

Question 4

A patient with a parathyroid tumor has persistently high blood calcium levels. Which of the following best explains the mechanism?

Accepted Answer

Excess PTH stimulates osteoclast activity, increasing bone resorption and raising blood calcium.

Question 5

Which of the following best describes the mechanism of action for peptide hormones?

Accepted Answer

They bind to cell surface receptors and often activate second messenger systems such as $$cAMP.$$

Question 6

Which of the following is a correct sequence for the Renin-Angiotensin-Aldosterone System (RAAS) activation?

Accepted Answer

Low blood pressure → renin release → angiotensinogen conversion to angiotensin I → angiotensin II → aldosterone secretion

Question 7

A patient with diabetes insipidus is unable to concentrate urine. Which hormone is most likely deficient, and what is its normal effect?

Accepted Answer

Antidiuretic hormone (ADH); promotes water reabsorption in the kidneys.

Question 8

Which of the following best illustrates a permissive hormone interaction?

Accepted Answer

Thyroid hormone increasing the number of adrenergic receptors, enhancing the effect of epinephrine.

Question 9

Which of the following is true regarding the transport of thyroid hormones in the blood?

Accepted Answer

Thyroid hormones are transported bound to thyroxine-binding globulin (TBG) and other plasma proteins.

Question 10

A patient is given a synthetic analog of a peptide hormone that acts via a G protein-coupled receptor (GPCR). Which of the following is the most likely sequence of events after the hormone binds its receptor?

Accepted Answer

Hormone binds receptor → activation of G protein → increase in $$cAMP$$ → activation of protein kinase A

Question 11

Which hormone is primarily responsible for stimulating red blood cell production in response to hypoxia, and where is it produced?

Accepted Answer

Erythropoietin; produced by the kidneys

Question 12

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

Accepted Answer

Insulin decreases blood glucose by promoting cellular uptake and storage as glycogen.

Question 13

A patient with chronic stress is likely to have elevated levels of which hormone, and what is a major effect of this hormone?

Accepted Answer

Cortisol; increases gluconeogenesis and suppresses the immune system.

Question 14

Which of the following is a correct example of negative feedback regulation in the endocrine system?

Accepted Answer

Elevated T3 and T4 inhibit TSH secretion from the anterior pituitary.

Question 15

Which hormone is secreted by the pineal gland and what is its primary function?

Accepted Answer

Melatonin; regulates circadian rhythms and sleep-wake cycles.

Question 16

A patient with a deficiency in calcitriol would most likely experience which of the following?

Accepted Answer

Decreased intestinal absorption of calcium, leading to hypocalcemia.

Question 17

Which of the following best describes the three stages of the General Adaptation Syndrome (GAS) in response to stress?

Accepted Answer

Alarm, resistance, exhaustion

Question 18

Which hormone is released from the posterior pituitary and what is its primary effect?

Accepted Answer

Oxytocin; stimulates uterine contractions and milk ejection.

Question 19

A patient with an insulinoma (insulin-secreting tumor) is most likely to experience which of the following symptoms?

Accepted Answer

Hypoglycemia, confusion, and possible loss of consciousness.

Question 20

Which of the following best describes the effect of receptor down-regulation in target cells?

Accepted Answer

Decreased sensitivity to a hormone due to fewer receptors.

Endocrine System: Structure, Function, and Regulation

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