The hypothalamus releases thyrotropin-releasing hormone (TRH), which stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH), which in turn stimulates the thyroid to release thyroxine (T4). When T4 levels in the blood become elevated, which of the following best describes the resulting feedback mechanism and its effect on TRH and TSH secretion?

Positive feedback; TRH and TSH secretion both increase to produce even more T4

Negative feedback; elevated T4 inhibits the hypothalamus and anterior pituitary, decreasing TRH and TSH secretion

Negative feedback; elevated T4 inhibits only the thyroid gland, while TRH and TSH secretion remain unchanged

Positive feedback; elevated T4 inhibits TRH and TSH secretion to amplify the hormonal signal

A student is labeling the layers of the heart wall from outermost to innermost. Which sequence is correct?

Endocardium → Myocardium → Epicardium

Epicardium → Myocardium → Endocardium

Myocardium → Epicardium → Endocardium

Epicardium → Endocardium → Myocardium

A biology student is studying negative feedback loops in the endocrine system. The hypothalamus releases thyrotropin-releasing hormone (TRH), which stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH). TSH then stimulates the thyroid to produce T3 and T4. Rising levels of T3 and T4 feed back to inhibit both the hypothalamus and the anterior pituitary. If a person's thyroid is surgically removed and no hormone replacement therapy is given, which of the following sequences of hormonal changes would be expected over time?

TRH increases; TSH increases; T3/T4 remain at zero

TRH decreases; TSH decreases; T3/T4 increase

TRH decreases; TSH increases; T3/T4 remain at zero

TRH increases; TSH decreases; T3/T4 remain at zero

HESI Science Practice Questions — Free Sampler (2026)

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Question 1Endocrine system (glands, hormones)
The hypothalamus releases thyrotropin-releasing hormone (TRH), which stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH), which in turn stimulates the thyroid to release thyroxine (T4). When T4 levels in the blood become elevated, which of the following best describes the resulting feedback mechanism and its effect on TRH and TSH secretion?
- APositive feedback; TRH and TSH secretion both increase to produce even more T4
- BNegative feedback; elevated T4 inhibits the hypothalamus and anterior pituitary, decreasing TRH and TSH secretion
- CNegative feedback; elevated T4 inhibits only the thyroid gland, while TRH and TSH secretion remain unchanged
- DPositive feedback; elevated T4 inhibits TRH and TSH secretion to amplify the hormonal signal
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Question 2Cardiovascular system
A student is labeling the layers of the heart wall from outermost to innermost. Which sequence is correct?
- AEndocardium → Myocardium → Epicardium
- BEpicardium → Myocardium → Endocardium
- CMyocardium → Epicardium → Endocardium
- DEpicardium → Endocardium → Myocardium
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Question 3Endocrine system (glands, hormones)
A biology student is studying negative feedback loops in the endocrine system. The hypothalamus releases thyrotropin-releasing hormone (TRH), which stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH). TSH then stimulates the thyroid to produce T3 and T4. Rising levels of T3 and T4 feed back to inhibit both the hypothalamus and the anterior pituitary. If a person's thyroid is surgically removed and no hormone replacement therapy is given, which of the following sequences of hormonal changes would be expected over time?
- ATRH increases; TSH increases; T3/T4 remain at zero
- BTRH decreases; TSH decreases; T3/T4 increase
- CTRH decreases; TSH increases; T3/T4 remain at zero
- DTRH increases; TSH decreases; T3/T4 remain at zero
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