Correct Answer: B

Rationale: The primary function of the skin in the integumentary system is to protect the body from external damage. The skin acts as a barrier against pathogens, UV radiation, and physical trauma. While the skin does help regulate body temperature by sweating and vasodilation, its main role is protection. Skin does not produce red blood cells; this is the function of the bone marrow. Hormones are primarily produced by endocrine glands, not the skin.

Correct Answer: A

Rationale: Insulin is the correct answer. Insulin is produced by the pancreas and plays a crucial role in regulating blood glucose levels. It facilitates the uptake of glucose into cells, helping to lower blood sugar levels. Glucagon, on the other hand, is also produced by the pancreas but functions to raise blood glucose levels by stimulating the release of glucose from the liver. Somatostatin is another hormone produced by the pancreas that helps regulate the endocrine system. Cortisol, produced by the adrenal glands, plays a role in stress response and metabolism, not by the pancreas.

Correct Answer: B

Rationale: The pituitary gland, often referred to as the 'master gland,' is the correct answer. It is responsible for regulating the release of hormones from other endocrine glands in the body. The pituitary gland controls various bodily functions and plays a crucial role in maintaining hormonal balance, making it a central and vital component of the endocrine system. The other options, such as the thyroid gland (A), adrenal gland (C), and pineal gland (D), have important functions in the endocrine system but are not specifically known as the 'master gland.'

Correct Answer: B

Rationale: Vitamin K is essential for the synthesis of proteins required for blood clotting. It specifically assists in the activation of clotting factors to prevent excessive bleeding from injuries. Vitamin K plays a crucial role in maintaining a balance between clotting and bleeding in the body. Choices A, C, and D are incorrect. Vitamin A is important for vision, immune function, and skin health. Vitamin C is essential for collagen synthesis and acts as an antioxidant. Vitamin D is crucial for calcium absorption and bone health.

Correct Answer: D

Rationale: The correct answer is D, the Hypothalamus. The hypothalamus is responsible for releasing key hormones like thyrotrophic-releasing hormone, growth hormone-releasing hormone, and gonadotropin-releasing hormone. These hormones play essential roles in regulating various body functions by influencing the activities of other endocrine glands. Choices A, B, and C are incorrect because the thymus is involved in immune function, the pituitary gland releases different hormones, and the pineal gland primarily produces melatonin, not the hormones mentioned in the question.