The posterior pituitary stores and releases:

Correct Answer: C

Rationale: The correct answer is C: Oxytocin and antidiuretic hormone (ADH). The posterior pituitary stores and releases oxytocin and ADH, also known as vasopressin. Oxytocin is involved in uterine contractions and milk ejection, while ADH regulates water reabsorption in the kidneys. Choices A, B, and D are incorrect because the posterior pituitary does not store or release growth hormone or prolactin.

Correct Answer: B

Rationale: The correct answer is B: ACTH. Adrenocorticotropic hormone (ACTH) is produced by the pituitary gland and stimulates the adrenal glands to produce and release glucocorticoids, such as cortisol. ADH (A) regulates water balance, GH (C) controls growth, and FSH (D) regulates reproductive functions. ACTH specifically targets the adrenal cortex to regulate glucocorticoid production, making it the correct choice in this scenario.

Correct Answer: B

Rationale: The correct answer is B: Pineal gland. The pineal gland secretes melatonin, a hormone that regulates the body's circadian rhythm. Melatonin helps control the sleep-wake cycle, making the pineal gland crucial for maintaining our internal body clock. The other choices, Thymus, Parathyroid, and Pituitary glands, are not directly involved in regulating circadian rhythms. Thymus is responsible for immune function, Parathyroid regulates calcium levels, and Pituitary gland controls various hormones but not specifically circadian rhythm. Hence, the pineal gland is the correct choice for this question.

Correct Answer: A

Rationale: The correct answer is A: Cretinism. Cretinism is a condition of severe hypothyroidism during childhood, leading to stunted growth, intellectual disability, and physical deformities. Myxoedema refers to severe hypothyroidism in adults, not children. Graves disease is a form of hyperthyroidism, opposite of hypothyroidism. Acromegaly is a condition caused by excess growth hormone, not related to thyroid dysfunction. Therefore, Cretinism is the correct answer for hypothyroidism in children due to its specific characteristics and presentation.

Correct Answer: A

Rationale: The correct answer is A: Parathyroid and thyroid. The parathyroid glands produce parathyroid hormone (PTH), which regulates calcium levels in the blood by increasing calcium absorption from the intestines and releasing calcium from bones. The thyroid gland produces calcitonin, which helps lower blood calcium levels by promoting calcium deposition in bones. The other choices (B: Adrenal medulla and pancreas, C: Testes, D: Parathyroid and thymus) are incorrect because they do not play a direct role in regulating calcium levels in the blood.