Endocrinology Exam Questions

Correct Answer: D

Rationale: Parathyroid hormone (PTH) is a hormone produced by the parathyroid glands in response to low blood calcium levels. Its main function is to raise calcium levels in the blood by acting on the bones, kidneys, and intestines. PTH stimulates the release of calcium from the bones, enhances the absorption of calcium by the intestines, and promotes the reabsorption of calcium by the kidneys. Therefore, it is secreted in increased amounts when blood calcium levels are below normal in order to maintain overall calcium balance in the body.

Correct Answer: A

Rationale: The receptors for non-steroid peptide hormones are typically found on the plasma membrane of target cells. These hormones are large or polar molecules that cannot easily diffuse through the cell membrane. Instead, they bind to specific receptors on the cell surface, initiating signaling pathways that eventually lead to changes within the cell. Once the peptide hormone binds to its receptor on the plasma membrane, secondary messenger systems are activated to relay the signal into the cell and initiate the appropriate cellular response. This distinct mechanism of action highlights the importance of the plasma membrane as the location of receptors for non-steroid peptide hormones.

Correct Answer: B

Rationale: Excess prolactin typically causes gynecomastia in men. Prolactin is a hormone primarily responsible for milk production in women. However, in men, elevated levels of prolactin can lead to various symptoms, with gynecomastia being one of the most common. Gynecomastia is the development of breast tissue in males, which can result in swelling and tenderness of the breasts. It is important to investigate the underlying cause of elevated prolactin levels as it could be due to various conditions such as pituitary tumors, certain medications, or thyroid disorders.

Correct Answer: A

Rationale: Myxoedema is a term used to describe severe hypothyroidism. The characteristic features of myxoedema include sinus bradycardia (choice B), solid oedema (choice C), and madarosis (choice D), which refers to loss of eyebrows and eyelashes. However, a butterfly rash is not a typical feature of myxoedema. A butterfly rash is commonly associated with conditions like systemic lupus erythematosus rather than myxoedema.

Correct Answer: D

Rationale: Growth hormone is primarily released during sleep, particularly during the first few hours of deep sleep. This release is pulsatile in nature, with the majority occurring at night. Growth hormone plays a critical role in growth, repair, and development of body tissues during periods of rest and sleep. Additionally, the secretion of growth hormone is also influenced by factors such as stress, exercise, and nutritional status.