HESI A2 Anatomy and Physiology Quizlet

Correct Answer: A

Rationale: The correct answer is A: Hemoglobin. Hemoglobin is a protein in red blood cells that binds to oxygen in the lungs and carries it to the body's tissues. Plasma is the liquid component of blood and does not directly carry oxygen. Platelets are responsible for blood clotting, not oxygen transport. Red blood cells contain hemoglobin and are the primary carriers of oxygen, making them indirectly responsible for carrying oxygen. However, the specific structure responsible for carrying oxygen is hemoglobin within red blood cells.

Correct Answer: C

Rationale: The correct answer is C: Pineal gland. The pineal gland secretes melatonin, a hormone responsible for regulating sleep-wake cycles. It receives signals from the retina about light levels, which helps to synchronize the body's internal clock. The hypothalamus (A) regulates various bodily functions but is not specifically responsible for sleep-wake cycles. The thalamus (B) is involved in relaying sensory information but not directly related to sleep regulation. The cerebellum (D) is primarily involved in motor control and coordination, not sleep regulation. Therefore, the pineal gland is the structure in the brain that directly regulates sleep and wakefulness.

Correct Answer: C

Rationale: The correct answer is C: Amygdala. The amygdala is a key structure in the brain responsible for processing emotions and forming emotional memories. It plays a crucial role in fear responses, emotional regulation, and memory consolidation. The other choices are incorrect because: A: Cerebrum is responsible for higher brain functions such as thinking, decision-making, and voluntary movements. B: Cerebellum is primarily involved in motor coordination and balance. D: Brainstem controls basic functions like breathing, heart rate, and consciousness levels.

Correct Answer: C

Rationale: The correct answer is C: Veins. Veins carry deoxygenated blood back to the heart. They have valves to prevent backflow and are thin-walled. Arteries (A) carry oxygenated blood away from the heart. Capillaries (B) are tiny vessels where oxygen exchange occurs. Lymphatic vessels (D) transport lymph, not blood.

Correct Answer: B

Rationale: The correct answer is B: Hypothalamus. The hypothalamus plays a crucial role in regulating body temperature through its control over thermoregulation processes. It receives input from temperature receptors in the body and initiates responses to maintain a stable internal temperature. The other choices are incorrect because the cerebellum is primarily responsible for coordination and balance, the medulla oblongata controls vital functions like breathing and heart rate, and the pineal gland regulates sleep-wake cycles through the secretion of melatonin.