which hormone is involved in regulating the sleep wake cycle

HESI A2

Anatomy and Physiology Hesi A2 Practice Test

1. Which hormone is involved in regulating the sleep-wake cycle?

A. Insulin
B. Melatonin
C. Cortisol
D. Thyroxine

Correct answer: B

Rationale: The correct answer is B: Melatonin. Melatonin, produced by the pineal gland, is the hormone involved in regulating the sleep-wake cycle. It plays a crucial role in signaling the body that it is time to sleep and is influenced by light exposure. Melatonin levels typically rise in the evening, promoting sleep, and decrease in the morning, helping in waking up. Choice A, Insulin, is involved in regulating blood sugar levels, not the sleep-wake cycle. Choice C, Cortisol, is a stress hormone that helps regulate metabolism and immune response but is not primarily involved in the sleep-wake cycle. Choice D, Thyroxine, is a hormone produced by the thyroid gland that regulates metabolism, growth, and development, but it is not directly involved in regulating the sleep-wake cycle.

2. What is the primary function of the integumentary system?

A. Protecting the body from external damage
B. Regulating body temperature
C. Producing vitamin D
D. Producing red blood cells

Correct answer: A

Rationale: The correct answer is A: Protecting the body from external damage. The primary function of the integumentary system, which includes the skin, hair, and nails, is to act as a physical barrier that protects the body from external damage such as pathogens, UV radiation, and mechanical injuries. While the integumentary system does play roles in regulating body temperature and producing vitamin D, its main and most crucial function is to provide a protective shield for the body. Choices B, C, and D are incorrect because although the integumentary system contributes to regulating body temperature and producing vitamin D, as well as housing cells involved in the immune response, its primary role is protection.

3. What is the role of the large intestine in the digestive system?

A. Absorbing nutrients
B. Absorbing water and forming solid waste
C. Breaking down fats
D. Secreting digestive enzymes

Correct answer: B

Rationale: The correct answer is B: Absorbing water and forming solid waste. The large intestine plays a crucial role in absorbing water from the remaining indigestible food matter and forming solid waste (feces) to be excreted from the body. This process helps in maintaining the body's fluid balance and eliminating waste efficiently. Choices A, C, and D are incorrect because the large intestine is not primarily responsible for absorbing nutrients, breaking down fats, or secreting digestive enzymes. These functions are mainly carried out in the small intestine.

4. What is the main function of the lymphatic system?

A. To transport oxygen
B. To produce hormones
C. To fight infections
D. To transport nutrients

Correct answer: C

Rationale: The main function of the lymphatic system is to fight infections. It achieves this by filtering lymph, returning excess tissue fluid to the bloodstream, and aiding in the body's immune response. The lymphatic system is crucial in protecting the body against pathogens and maintaining overall health. Choices A, B, and D are incorrect because transporting oxygen, producing hormones, and transporting nutrients are functions performed by other systems in the body, like the respiratory, endocrine, and circulatory systems, respectively.

5. What is the primary function of the alveoli in the lungs?

A. Removing carbon dioxide from the blood
B. Exchanging oxygen and carbon dioxide
C. Transporting oxygen to the bloodstream
D. Filtering blood

Correct answer: B

Rationale: The primary function of the alveoli in the lungs is to exchange oxygen and carbon dioxide. The alveoli are tiny air sacs in the lungs responsible for this gas exchange during breathing. Oxygen diffuses from the inhaled air into the blood in the capillaries surrounding the alveoli, while carbon dioxide diffuses from the blood into the alveoli to be exhaled out of the body. Choice A is incorrect because the alveoli primarily facilitate the exchange of gases, not just the removal of carbon dioxide. Choice C is incorrect as the alveoli do not transport oxygen to the bloodstream but rather facilitate the exchange of gases. Choice D is incorrect as the alveoli are not involved in filtering blood but in gas exchange to ensure proper oxygenation and removal of carbon dioxide in the respiratory process.