Quizlet HESI A2 Anatomy and Physiology

Correct Answer: A

Rationale: The correct answer is A: Pineal gland. The pineal gland is located in the brain and is responsible for producing melatonin, which regulates sleep-wake cycles. Melatonin is not produced by the thyroid gland (B), pituitary gland (C), or adrenal gland (D). The thyroid gland produces hormones that regulate metabolism, the pituitary gland regulates various hormones, and the adrenal gland produces hormones like cortisol and adrenaline. Therefore, the pineal gland is the correct answer as it specifically produces melatonin.

Correct Answer: A

Rationale: The correct answer is A: Transporting oxygen. Hemoglobin is a protein in red blood cells that binds to oxygen in the lungs and carries it to tissues throughout the body. This process is essential for cellular respiration and energy production. The other choices are incorrect because hemoglobin does not primarily function in carrying nutrients, clotting blood, or removing carbon dioxide from the blood. Transporting oxygen is the main and crucial role of hemoglobin in the blood.

Correct Answer: C

Rationale: The correct answer is C: Vitamin D. Vitamin D is essential for calcium absorption in the intestines by promoting the production of proteins that transport calcium. Without sufficient Vitamin D, the body cannot effectively absorb calcium, leading to potential bone and muscle weakness. Choice A: Vitamin A is not directly involved in calcium absorption. Choice B: Vitamin C is important for collagen synthesis and immune function but does not play a significant role in calcium absorption. Choice D: Vitamin K is primarily involved in blood clotting and bone health but does not directly affect calcium absorption.

Correct Answer: B

Rationale: The primary function of the digestive system is to break down food through mechanical and chemical processes, and absorb nutrients for the body's energy and growth. This process involves enzymes, acids, and various organs like the stomach and intestines. Option A is incorrect as oxygen transportation is primarily done by the respiratory system. Option C is incorrect as hormone production is mainly regulated by the endocrine system. Option D is incorrect as blood transportation is the role of the circulatory system.

Correct Answer: A

Rationale: The correct answer is A: Pineal gland. The pineal gland is located in the brain and is responsible for producing melatonin, which regulates sleep-wake cycles. Melatonin is not produced by the thyroid gland (B), pituitary gland (C), or adrenal gland (D). The thyroid gland produces hormones that regulate metabolism, the pituitary gland regulates various hormones, and the adrenal gland produces hormones like cortisol and adrenaline. Therefore, the pineal gland is the correct answer as it specifically produces melatonin.