Anatomy and Physiology Hesi A2 Practice Test

Correct Answer: B

Rationale: The correct answer is B: Melatonin. Melatonin is a hormone produced by the pineal gland that plays a crucial role in regulating the sleep-wake cycle. It is released in response to darkness and helps signal to the body that it is time to sleep. Melatonin levels increase at night, promoting sleep, and decrease during the day, promoting wakefulness. A: Insulin is a hormone that helps regulate blood sugar levels, not the sleep-wake cycle. C: Cortisol is a stress hormone involved in the body's response to stress and is not directly related to the sleep-wake cycle. D: Thyroxine is a hormone produced by the thyroid gland that regulates metabolism and energy levels, not the sleep-wake cycle.

Correct Answer: B

Rationale: The correct answer is B: To absorb nutrients. The small intestine is responsible for absorbing nutrients from digested food into the bloodstream for distribution to the rest of the body. This process involves the absorption of proteins, carbohydrates, fats, vitamins, and minerals. The small intestine does not primarily break down food (A), as this is mainly done in the stomach. While the small intestine does secrete digestive enzymes (C), its primary function is absorption. Lastly, the small intestine does not store glucose (D), as glucose is stored in the liver and muscles.

Correct Answer: D

Rationale: The correct answer is D: Larynx. The larynx is an organ of the respiratory system because it plays a crucial role in producing sound and facilitating the passage of air to the lungs. It contains the vocal cords and is located in the throat. The other choices (A: Pancreas, B: Brain, C: Urethra) are not part of the respiratory system. The pancreas is part of the digestive system, the brain is part of the nervous system, and the urethra is part of the urinary system.

Correct Answer: B

Rationale: The correct answer is B: Mitochondria. Mitochondria are known as the powerhouse of the cell because they are responsible for producing energy in the form of ATP through cellular respiration. They contain enzymes necessary for the production of ATP, which is the main energy currency of the cell. The other choices are incorrect because: A: Nucleus - Responsible for controlling cell activities and storing genetic material. C: Ribosome - Responsible for protein synthesis, not energy production. D: Golgi apparatus - Responsible for processing and packaging proteins for secretion, not energy production.

Correct Answer: B

Rationale: The correct answer is B: Melatonin. Melatonin is a hormone produced by the pineal gland that plays a crucial role in regulating the sleep-wake cycle. It is released in response to darkness and helps signal to the body that it is time to sleep. Melatonin levels increase at night, promoting sleep, and decrease during the day, promoting wakefulness. A: Insulin is a hormone that helps regulate blood sugar levels, not the sleep-wake cycle. C: Cortisol is a stress hormone involved in the body's response to stress and is not directly related to the sleep-wake cycle. D: Thyroxine is a hormone produced by the thyroid gland that regulates metabolism and energy levels, not the sleep-wake cycle.