Endocrinology Exam Questions and Answers

Correct Answer: D

Rationale: Binding proteins are essential in transporting hormones through the bloodstream and protecting them from rapid degradation by enzymes. These proteins do not actually mediate the hormonal effects themselves. Hormonal effects are typically mediated by the hormone-receptor interactions at target cells. Binding proteins primarily serve as carriers for hormones and maintain their stability and availability in the circulation.

Correct Answer: C

Rationale: Oxytocin is a hormone that is produced in both males and females. In females, oxytocin plays a crucial role in various physiological processes, notably during labor and childbirth. Oxytocin acts on the smooth muscles of the uterus, causing them to contract during labor (parturition) and helps in the ejection of milk during breastfeeding. This hormone is primarily synthesized in the paraventricular nucleus (PVN) and the supraoptic nucleus (SON) of the hypothalamus and stored in the posterior pituitary gland before being released into the bloodstream. Overall, oxytocin's main function is to stimulate smooth muscle contraction in the uterus and the mammary glands.

Correct Answer: D

Rationale: Oxytocin and antidiuretic hormone (ADH; vasopressin) are both synthesized in the hypothalamus, specifically in the supraoptic and paraventricular nuclei. After synthesis, they are transported along axons to the posterior pituitary where they are stored until they are released into the bloodstream when needed. This is why they are released from the posterior pituitary, not the anterior pituitary. These hormones have different functions in the body, with oxytocin being involved in labor and breastfeeding, while ADH plays a role in regulating water balance and blood pressure.

Correct Answer: B

Rationale: Hemoglobin A1c, also known as HbA1c or glycated hemoglobin, is a blood test that measures the average blood glucose level over the previous 2 to 3 months. This test is useful in monitoring long-term blood glucose control in individuals with diabetes. Hemoglobin A1c provides an indication of how well blood glucose levels have been controlled over time, reflecting the average blood sugar levels during the lifespan of red blood cells, which is typically around 2 to 3 months. A higher Hemoglobin A1c level indicates poorer blood glucose control and an increased risk of diabetes complications.

Correct Answer: D

Rationale: Blood calcium levels are primarily regulated by the actions of parathyroid hormone (PTH) and Vitamin D. Vitamin D plays a crucial role in maintaining calcium balance in the body by promoting the absorption of calcium from the intestines. When blood calcium levels are low, Vitamin D works to increase absorption of calcium to raise the levels back to normal. Therefore, elevated blood calcium levels are commonly associated with excess Vitamin D intake or conditions that increase Vitamin D levels, such as hypervitaminosis D.