which hormone is responsible for regulating the sleep wake cycle

HESI A2

HESI A2 Practice Test Anatomy and Physiology

1. Which hormone is responsible for regulating the sleep-wake cycle?

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

Correct answer: A

Rationale: Melatonin, produced by the pineal gland, regulates the sleep-wake cycle by responding to light and darkness in the environment. It plays a crucial role in signaling the body when it's time to sleep and wake up, helping to establish and maintain a healthy circadian rhythm. Thyroxine, Insulin, and Cortisol do not directly regulate the sleep-wake cycle, making them incorrect choices for this question.

2. What is the main function of the endocrine system?

A. To fight infections
B. To regulate body functions through hormones
C. To produce red blood cells
D. To transport oxygen

Correct answer: B

Rationale: The main function of the endocrine system is to regulate various body functions by releasing hormones, which act as chemical messengers. These hormones help maintain homeostasis, regulate metabolism, growth, development, and other essential functions in the body. Option A is incorrect as fighting infections is primarily the role of the immune system, not the endocrine system. Option C is incorrect as the production of red blood cells mainly occurs in the bone marrow. Option D is incorrect as the transportation of oxygen is primarily carried out by the respiratory and circulatory systems. Therefore, option B is the correct answer as it accurately describes the primary role of the endocrine system.

3. What is the primary function of the respiratory system?

A. To transport oxygen and remove carbon dioxide
B. To regulate body temperature
C. To fight infections
D. To produce energy

Correct answer: A

Rationale: The primary function of the respiratory system is to facilitate the exchange of oxygen and carbon dioxide between the air and the bloodstream. Oxygen is taken in during inhalation and transported to cells, while carbon dioxide is removed during exhalation as a waste product of cellular metabolism. Choices B, C, and D are incorrect as they do not reflect the primary function of the respiratory system. Regulating body temperature is mainly controlled by the thermoregulatory system, fighting infections is a function of the immune system, and producing energy is primarily done by the metabolic system.

4. What is the role of the stomach in digestion?

A. To absorb nutrients
B. To break down food
C. To secrete digestive enzymes
D. To transport nutrients

Correct answer: B

Rationale: The correct answer is B: To break down food. The stomach's primary function in digestion is to mechanically and chemically break down food. It achieves this by utilizing gastric acid and digestive enzymes to convert food into chyme, a semi-liquid mixture. The chyme is then passed to the small intestine for further processing and absorption of nutrients. Choices A, C, and D are incorrect because the stomach's main role is not to absorb nutrients, secrete digestive enzymes, or transport nutrients; instead, it primarily focuses on breaking down food.

5. What is the main function of white blood cells?

A. To carry oxygen
B. To fight infections
C. To carry nutrients
D. To remove waste products

Correct answer: B

Rationale: The main function of white blood cells, also known as leukocytes, is to fight infections and foreign invaders to protect the body from harm. They play a crucial role in the immune system by identifying and destroying pathogens like bacteria and viruses, essential for maintaining the body's health and overall immunity. Choices A, C, and D are incorrect as carrying oxygen is primarily done by red blood cells, carrying nutrients is a function of various body systems, and removing waste products is mainly the role of the kidneys and liver, not white blood cells.