HESI A2
HESI A2 Anatomy and Physiology Practice Test
1. Which structure of the respiratory system is involved in gas exchange?
- A. Trachea
- B. Bronchioles
- C. Alveoli
- D. Larynx
Correct answer: C
Rationale: The alveoli are the primary site for gas exchange in the respiratory system. These tiny air sacs in the lungs are where oxygen is taken up into the bloodstream and carbon dioxide is released from the bloodstream into the lungs to be exhaled. The trachea (Choice A) is the windpipe that carries air to and from the lungs but is not directly involved in gas exchange. Bronchioles (Choice B) are smaller airway branches that lead to the alveoli but do not participate in gas exchange themselves. The larynx (Choice D) plays a role in producing sound and protecting the airway but is not primarily responsible for gas exchange.
2. Which of the following is an organ of the respiratory system?
- A. Brain
- B. Larynx
- C. Urethra
- D. Pancreas
Correct answer: B
Rationale: The larynx is an essential organ of the respiratory system. It plays a crucial role in producing sound, protecting the trachea from food aspiration, and regulating the airflow to and from the lungs. The brain is part of the nervous system, the urethra is part of the urinary system, and the pancreas is part of the digestive system. Therefore, they are not directly related to the respiratory system's functions.
3. What is the primary function of the hypothalamus?
- A. Regulates body balance and thermoregulation
- B. Controls hunger and thirst
- C. Regulates sleep and circadian rhythms
- D. Controls voluntary movements
Correct answer: A
Rationale: The primary function of the hypothalamus is to regulate body balance and thermoregulation. It plays a crucial role in maintaining overall body equilibrium by controlling functions such as body temperature and water balance. While the hypothalamus is also involved in hunger and thirst regulation, its main role is to ensure homeostasis by monitoring and adjusting body balance and temperature. Choices B, C, and D are incorrect because hunger and thirst regulation, sleep and circadian rhythm regulation, and control of voluntary movements are secondary functions of the hypothalamus compared to its primary role in maintaining body balance and thermoregulation.
4. Which hormone regulates the sleep-wake cycle?
- A. Melatonin
- B. Insulin
- C. Cortisol
- D. Thyroxine
Correct answer: A
Rationale: Melatonin, produced by the pineal gland, is the hormone that regulates the sleep-wake cycle. Its secretion is influenced by light exposure, with levels typically rising in the evening to promote sleep and falling in the morning to encourage wakefulness. Insulin is involved in regulating blood sugar levels, not the sleep-wake cycle. Cortisol plays a role in the body's stress response and circadian rhythm but is not the primary hormone regulating sleep-wake cycles. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism, not the sleep-wake cycle.
5. What is the term for red blood cell production?
- A. Hematopoiesis
- B. Erythropoiesis
- C. Phagocytosis
- D. Thrombopoiesis
Correct answer: B
Rationale: The correct term for red blood cell production is erythropoiesis. This process specifically refers to the production of red blood cells, mainly occurring in the bone marrow. Hematopoiesis is a broader term that encompasses the production of all blood cells, including red blood cells, white blood cells, and platelets. Phagocytosis is the process of engulfing and digesting particles by cells like macrophages, not related to red blood cell production. Thrombopoiesis is the production of platelets, not red blood cells.
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