HESI A2
HESI A2 Practice Test Anatomy and Physiology
1. Which type of blood cell is responsible for carrying oxygen?
- A. Red blood cells
- B. White blood cells
- C. Platelets
- D. Plasma cells
Correct answer: A
Rationale: The correct answer is A: Red blood cells. Red blood cells, also known as erythrocytes, are specialized cells designed to transport oxygen from the lungs to tissues and organs throughout the body. These cells contain hemoglobin, a protein that binds to oxygen molecules in the lungs and releases them in other parts of the body where oxygen is needed for cellular respiration. White blood cells (choice B) are part of the immune system, responsible for fighting infections. Platelets (choice C) are involved in blood clotting. Plasma cells (choice D) are a type of white blood cell that produces antibodies to help the body fight off infections.
2. What is the primary function of the skin?
- A. To regulate body temperature
- B. To protect the body from external damage
- C. To produce vitamin D
- D. To produce red blood cells
Correct answer: B
Rationale: The primary function of the skin is to protect the body from external damage. While the skin also helps regulate body temperature and produces vitamin D in response to sunlight, its main role is to act as a barrier against harmful external factors, such as pathogens and physical injuries. Choices A, C, and D are incorrect because although the skin does play a role in regulating body temperature and producing vitamin D, its primary function is providing protection against external threats.
3. The sebaceous glands are part of which system?
- A. Endocrine system
- B. Digestive system
- C. Respiratory system
- D. Integumentary system
Correct answer: D
Rationale: The sebaceous glands are a component of the integumentary system, which includes the skin, hair, nails, and associated structures. Sebaceous glands are typically found throughout the skin and are responsible for producing an oily substance called sebum, which helps keep the skin and hair lubricated and moisturized. The endocrine system (Choice A) consists of glands that produce hormones, the digestive system (Choice B) is responsible for processing food, and the respiratory system (Choice C) is involved in breathing and gas exchange.
4. What is the function of the alveoli in the lungs?
- A. To absorb oxygen
- B. To remove carbon dioxide
- C. To exchange gases
- D. To regulate blood pressure
Correct answer: C
Rationale: The alveoli are tiny air sacs in the lungs responsible for the exchange of gases, specifically oxygen and carbon dioxide, during breathing. Oxygen is taken in and carbon dioxide is released through this process, enabling the body to receive oxygen and expel carbon dioxide. Choice A is incorrect because the alveoli do not absorb oxygen but facilitate the exchange of gases. Choice B is incorrect as the alveoli do not remove carbon dioxide but aid in the exchange of gases. Choice D is incorrect as the alveoli are not involved in regulating blood pressure but in gas exchange.
5. 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.
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