HESI A2 Anatomy and Physiology Quizlet

Correct Answer: B

Rationale: The correct answer is B: Adrenaline. The adrenal medulla is part of the adrenal glands and is responsible for producing adrenaline, also known as epinephrine. Adrenaline is a hormone that plays a crucial role in the body's fight or flight response, increasing heart rate, blood flow to muscles, and overall alertness in response to stress or danger. Insulin (A) is produced by the pancreas to regulate blood sugar levels, cortisol (C) is produced by the adrenal cortex to regulate stress response and metabolism, and melatonin (D) is produced by the pineal gland to regulate sleep-wake cycles.

Correct Answer: B

Rationale: The correct answer is B: Mitochondria. Mitochondria are known as the powerhouse of the cell because they are responsible for energy production through the process of cellular respiration. They produce ATP, the main energy currency of the cell. The other choices are incorrect because the nucleus is responsible for storing genetic material, ribosomes are involved in protein synthesis, and the Golgi apparatus is responsible for packaging and transporting proteins. Therefore, only the mitochondria play a direct role in energy production within the cell.

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: B

Rationale: The correct answer is B: Ball and socket joint. The hip joint is a ball and socket joint because the rounded head of the femur fits into the cup-shaped acetabulum of the pelvis, allowing for a wide range of motion in multiple directions. This design provides stability and support while enabling movements like flexion, extension, abduction, adduction, and rotation. A hinge joint (A) allows movement in one plane like the elbow, not the hip. Pivot joint (C) allows rotation around a central axis like the neck, not the hip. Saddle joint (D) allows movement in multiple directions but not as freely as a ball and socket joint.

Correct Answer: A

Rationale: The correct answer is A: Melatonin. Melatonin is a hormone produced by the pineal gland that plays a key role in regulating the sleep-wake cycle. It helps control the body's internal clock and signals the brain when it's time to sleep. Melatonin levels typically rise in the evening, promoting sleep, and decrease in the morning, promoting wakefulness. Summary of incorrect choices: B: Insulin - Insulin is a hormone that regulates blood sugar levels, not the sleep-wake cycle. C: Cortisol - Cortisol is a stress hormone that helps regulate metabolism and immune response, but it does not directly control the sleep-wake cycle. D: Thyroxine - Thyroxine is a hormone produced by the thyroid gland that regulates metabolism, growth, and development, but it is not directly involved in the sleep-wake cycle regulation.