The secretions from which of these glands differs between males and females?

Correct Answer: C

Rationale: The correct answer is C: Gonadal glands. These glands differ between males and females in terms of the hormones they secrete. In males, the gonadal glands (testes) produce testosterone, while in females, the gonadal glands (ovaries) produce estrogen and progesterone. Adrenal glands (A) secrete hormones like cortisol and adrenaline, which are not gender-specific. Parathyroid glands (B) regulate calcium levels and are not gender-specific. Pancreas (D) secretes insulin and glucagon, which are also not gender-specific. Therefore, the key difference in secretions between males and females lies in the gonadal glands.

Correct Answer: A

Rationale: The correct answer is A because thyroid hormone is a lipid-soluble hormone that can diffuse across the cell membrane and bind to intracellular receptors within the nuclei. This binding activates gene transcription, leading to various metabolic effects. Choice B is incorrect because thyroid hormone actually has a significant impact on body metabolism. Choice C is incorrect as thyroid hormone does not directly affect blood vessel adrenergic receptors or blood pressure. Choice D is incorrect as thyroid hormone actually acts to increase basal metabolic rate, not decrease it.

Correct Answer: D

Rationale: The correct answer is D: humoral stimulation. This mechanism directly responds to changing blood levels of ions and nutrients. Humoral stimulation refers to the regulation of hormone secretion in response to changes in blood levels of various substances like ions and nutrients. It is a feedback mechanism that helps maintain homeostasis by adjusting hormone levels based on the body's needs. A: Rapid oxidation of carbohydrates is not related to endocrine control systems responding to changing blood levels of ions and nutrients. B: Catabolic inhibition does not directly respond to changing blood levels of ions and nutrients. C: Protein synthesis is not a mechanism that directly responds to changing blood levels of ions and nutrients.

Correct Answer: D

Rationale: The correct answer is D: Parathyroid hormone is the single most important regulator of calcium levels in the blood. Parathyroid hormone plays a crucial role in maintaining calcium homeostasis by stimulating bone resorption, increasing calcium reabsorption in the kidneys, and activating vitamin D to enhance calcium absorption in the intestines. It acts to raise blood calcium levels when they are low. Explanation for other choices: A: Increased calcitonin levels actually lower blood calcium levels by promoting calcium deposition in bones. B: High calcium levels do not cause bone resorption; it is actually the opposite as mentioned in choice D. C: Parathyroid hormone does not increase osteoblast activity; it primarily affects osteoclasts to release calcium from bones.

Correct Answer: D

Rationale: The correct answer is D: breaking down nutrients. Hormones are chemical messengers that regulate various physiological processes in the body. Hormones do not directly break down nutrients; instead, they regulate the processes involved in nutrient breakdown. A: maintaining homeostasis is a function of hormones as they help regulate internal balance. B: influencing metabolism is a function of hormones as they regulate energy production and utilization. C: influencing growth and development is a function of hormones as they play a crucial role in the growth and maturation of cells and tissues.