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 protect against pathogens. The skin acts as a physical barrier that prevents harmful pathogens from entering the body. It also contains specialized immune cells that help to fight off infections. Vitamin D production (choice A) primarily occurs in the skin but is not the main function of skin protection. Storing nutrients (choice C) is not a primary function of the skin. While the skin does play a role in thermoregulation (choice D), its main function in protecting the body is to defend against pathogens.

Correct Answer: B

Rationale: The correct answer is B: Endocrine glands secrete chemicals into the blood. This is because endocrine glands release hormones directly into the bloodstream to regulate various physiological functions throughout the body. Other choices are incorrect: A is incorrect as endocrine glands do not absorb chemicals from the blood; C is incorrect because endocrine glands do not filter chemicals from the blood; and D is incorrect as endocrine glands do not absorb chemicals from the lymphatic system.

Correct Answer: D

Rationale: The correct answer is D: Hypothalamus. The hypothalamus releases thyrotrophic-releasing hormone (TRH), which stimulates the release of thyroid-stimulating hormone (TSH) from the pituitary gland. It also secretes growth hormone-releasing hormone (GHRH) to stimulate growth hormone release and gonadotropin-releasing hormone (GnRH) to regulate the secretion of gonadotropins (FSH and LH). The other choices are incorrect because: A: Thymus - The thymus is primarily involved in immune function and does not release the mentioned hormones. B: Pituitary gland - While the pituitary gland responds to the hormones released by the hypothalamus, it does not release TRH, GHRH, or GnRH directly. C: Pineal gland - The pineal gland mainly secretes melatonin and is not involved in releasing the mentioned hormones related to growth, thyroid function, and reproduction

Correct Answer: D

Rationale: The correct answer is D: Pinna. The pinna, also known as the auricle, is the most visible part of the ear. It is the external, cartilaginous structure that helps collect and funnel sound waves into the ear canal. The ear canal, choice A, is not the most visible part as it is mostly within the ear. The cochlea, choice B, and the organ of Corti, choice C, are internal structures within the ear responsible for processing sound signals, but they are not visible from the outside. Therefore, the pinna is the correct answer as it is the visible part of the ear that is easily recognizable on the exterior.