The release of oxytocin is controlled by _____ feedback.

Correct Answer: C

Rationale: The correct answer is C: positive feedback. Oxytocin release is triggered by the positive feedback mechanism. When oxytocin is released in response to a stimulus, it further stimulates the release of more oxytocin, intensifying the effect. This continuous loop enhances the initial response, leading to a cascade effect. Negative feedback (choice A) works to maintain homeostasis by counteracting the initial stimulus, which is not the case for oxytocin release. Neutral feedback (choice B) does not play a significant role in regulating hormone release. Choice D is incomplete and irrelevant.

Correct Answer: B

Rationale: The correct answer is B: right atrium of the heart. Atrial natriuretic hormone (ANH) is produced by specialized cells in the right atrium of the heart called atrial myocytes. When the heart senses an increase in blood volume or pressure, these cells release ANH to help regulate fluid and electrolyte balance by promoting sodium and water excretion by the kidneys. Choices A, C, and D are incorrect because ANH is not produced by the kidney tubules, adrenal cortex, or pancreas. The primary site of ANH production is specifically within the cardiac atria.

Correct Answer: B

Rationale: Correct Answer: B - aldosterone Rationale: 1. Aldosterone is a hormone produced by the adrenal glands that primarily regulates salt and water balance, not fuel metabolism. 2. Insulin helps in lowering blood sugar levels by facilitating glucose uptake by cells. 3. Glucagon stimulates the release of glucose from the liver to raise blood sugar levels. 4. Cortisol plays a role in mobilizing energy stores during stress. Summary: Aldosterone does not directly impact fuel metabolism like insulin, glucagon, and cortisol do. Insulin lowers blood sugar levels, glucagon raises blood sugar levels, and cortisol mobilizes energy stores during stress.

Correct Answer: C

Rationale: The correct answer is C: Myxedema. Insufficient levels of thyroid hormone in adults lead to myxedema due to decreased metabolism and energy production. Goiter (A) is the enlargement of the thyroid gland, not caused by low thyroid hormone levels. Tetany (B) is muscle spasms due to low calcium levels, not related to thyroid hormone deficiency. Cretinism (D) is a condition of severe hypothyroidism in infants, not in adults. Therefore, the correct choice is C as it directly relates to the consequences of low thyroid hormone levels in adults.

Correct Answer: C

Rationale: The correct answer is C: Oestrogen. Oestrogen is the primary female sex hormone responsible for the development of secondary sexual characteristics such as breast development, regulation of the menstrual cycle, and maintenance of the reproductive system. Adrenaline (A) is a stress hormone that prepares the body for fight or flight responses. Glucagon (B) is a hormone that raises blood sugar levels. Calcitonin (D) is involved in regulating calcium levels in the body. These hormones do not play a direct role in the development of female secondary sexual characteristics.