The posterior pituitary stores and secretes _________.

Correct Answer: A

Rationale: The posterior pituitary gland secretes anti-diuretic hormone (ADH) and oxytocin, which are produced in the hypothalamus and then transported and stored in the posterior pituitary before being released into the bloodstream. ADH, also known as vasopressin, helps regulate water balance in the body by controlling the reabsorption of water in the kidneys. Oxytocin, on the other hand, plays a role in various reproductive functions such as labor and lactation, as well as social bonding and behavior.

Correct Answer: A

Rationale: Thyrotoxicosis, also known as hyperthyroidism, is a condition characterized by excessive thyroid hormone production by the thyroid gland. Symptoms of thyrotoxicosis can include weight loss, heat intolerance, tremors, hyperactivity, and fatigue. While musculoskeletal symptoms such as weakness and tremors are common in thyrotoxicosis, true myopathy (muscle disease) is not a typical feature of the condition. Therefore, myopathy is the correct choice among the given options.

Correct Answer: D

Rationale: Thyroid-stimulating hormone (TSH) is a hormone produced by the anterior pituitary gland. It stimulates the thyroid gland to produce and release thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3). TSH secretion is regulated by the hypothalamus via the release of thyrotropin-releasing hormone (TRH). TRH acts on the anterior pituitary gland to stimulate the production and release of TSH. Therefore, TSH secretion is indeed inhibited by TRH, not stimulated as in the other options.

Correct Answer: D

Rationale: Persistent muscular weakness is characteristic of myxoedema, which is severe hypothyroidism. Myxoedema can lead to general weakness and fatigue, as thyroid hormones play a crucial role in controlling metabolism and energy production in the body. Other symptoms of myxoedema include cold intolerance, weight gain, dry skin, and hair loss. Conn's syndrome (hyperaldosteronism) is characterized by hypertension and low potassium levels, not persistent muscular weakness. Acromegaly is a condition resulting from excess growth hormone production, leading to enlarged body parts and metabolic changes but not specifically muscular weakness. Hyperparathyroidism is associated with high levels of parathyroid hormone, which can lead to bone weakening and calcium imbalance, but it is not typically a primary cause of muscular weakness.

Correct Answer: A

Rationale: Hypertonicity (increased osmolarity or high concentration of solutes in the blood) is the most potent stimulus for the hypothalamic production of arginine vasopressin (also known as antidiuretic hormone or ADH). When the body senses increased plasma osmolality, the osmoreceptors in the hypothalamus stimulate the release of vasopressin from the posterior pituitary gland. Vasopressin acts on the kidneys to increase water reabsorption and decrease urine output, helping to restore normal osmolarity. This mechanism helps to conserve water and maintain body fluid balance in response to dehydration or increased solute concentration in the blood.

Correct Answer: D

Rationale: Follicle-stimulating hormone (FSH) is one of the hormones produced in the anterior pituitary gland. The anterior pituitary gland secretes several hormones that regulate various functions in the body. FSH plays a crucial role in both males and females. In females, FSH stimulates the growth and maturation of ovarian follicles, which contain the eggs. In males, FSH is essential for the production of sperm in the testes. The production and release of FSH are regulated by the hypothalamus and gonadotropin-releasing hormone (GnRH).

Correct Answer: D

Rationale: Osteomalacia is a condition in which there is a softening of the bones due to a deficiency in vitamin D or calcium. It is not a cause of hypocalcemia, as it is a result of low levels of calcium in the bloodstream. The other options listed are potential causes of hypocalcemia:

Correct Answer: B

Rationale: Cushing's syndrome is a disorder caused by prolonged exposure to high levels of cortisol hormone. While Cushing's syndrome can manifest with a variety of symptoms, peripheral neuropathy is not a typical feature of this condition. Cushing's syndrome is commonly associated with symptoms such as hirsutism (excessive hair growth), purple striae (skin stretch marks that are purple in color), and acne due to the hormonal imbalances it creates. Peripheral neuropathy, which involves damage to the peripheral nerves leading to symptoms like numbness, tingling, and weakness in the extremities, is not a characteristic symptom of Cushing's syndrome.

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.