Which of the following is the most important effect of somatotropic hormone?

Correct Answer: B

Rationale: The correct answer is B: Growth of the musculoskeletal system. Somatotropic hormone, also known as growth hormone, plays a crucial role in stimulating growth and development of bones, muscles, and tissues. It promotes the growth of the musculoskeletal system by stimulating the production of proteins that are essential for muscle and bone growth. This effect is the most important function of somatotropic hormone as it directly impacts overall body growth and physical development. Explanation for other choices: A: Promotion of the urinary excretion of calcium - This is not a primary function of somatotropic hormone. Calcium regulation is mainly controlled by other hormones like parathyroid hormone and calcitonin. C: Regulation of sodium and water balance - This function is primarily controlled by hormones like aldosterone and antidiuretic hormone, not somatotropic hormone. D: Initiates and sustains labor to terminate pregnancy - Labor initiation is regulated by hormones like oxytocin and prostaglandins, not somat

Correct Answer: A

Rationale: The correct answer is A because endocrine glands are ductless and release hormones directly into the bloodstream to reach target organs, while exocrine glands release their secretions through ducts onto the body's surface or into specific locations. This distinction is crucial as it highlights the mode of transportation of their secretions. Choices B, C, and D are incorrect because exocrine glands do not release waste; they release enzymes, sweat, etc. Exocrine glands can be formed by various types of tissues, not just connective tissue. Additionally, exocrine glands do not necessarily act completely independently; they can be part of a system or network but still release their secretions through ducts.

Correct Answer: A

Rationale: The correct answer is A because glucagon stimulates the breakdown of glycogen into glucose, increasing blood glucose levels. Glucagon does not slow down glucose formation from lactic acid (B), decrease glycogen conversion (C), or speed up protein synthesis (D). Glucagon's primary function is to raise blood glucose levels in response to low blood sugar levels.

Correct Answer: B

Rationale: The correct answer is B: negative feedback system. In a negative feedback system, the body's response to a stimulus works to counteract the initial stimulus, bringing the body back to its set point. In the context of the question, hormone release stops when the stimulus is satisfied, which is characteristic of a negative feedback system. A: Positive feedback system amplifies the initial stimulus rather than counteracting it. C: Lock and key system refers to how enzymes bind to specific substrates, not related to hormone regulation. D: Solar system is unrelated to physiological processes.

Correct Answer: C

Rationale: The correct answer is C: Iodine. Iodine is essential for the production of thyroid hormones T3 and T4. These hormones regulate metabolism, growth, and development. Potassium (A), Sodium (B), and Calcium (D) do not play a direct role in thyroid function. Potassium and Sodium are electrolytes important for nerve function and fluid balance, while Calcium is crucial for bone health and muscle function. Therefore, the correct answer is Iodine as it is specifically required for normal thyroid function.