HESI A2
HESI A2 Practice Test Anatomy and Physiology
1. 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.
2. Which type of muscle tissue is found in the heart?
- A. Smooth muscle
- B. Cardiac muscle
- C. Skeletal muscle
- D. Striated muscle
Correct answer: B
Rationale: Cardiac muscle tissue, represented by choice B, is the correct answer. Cardiac muscle tissue is unique to the heart and responsible for its involuntary contractions that pump blood throughout the body. Smooth muscle (choice A) is found in the walls of hollow organs, skeletal muscle (choice C) is attached to bones for movement, and striated muscle (choice D) is a general term that can refer to both cardiac and skeletal muscle but is not specific to the heart.
3. Which vitamin is essential for the synthesis of collagen?
- A. Vitamin C
- B. Vitamin D
- C. Vitamin B12
- D. Vitamin K
Correct answer: A
Rationale: The correct answer is Vitamin C. Vitamin C is essential for the synthesis of collagen, a protein crucial for maintaining the structure and integrity of skin, blood vessels, and bones. It plays a key role in the hydroxylation of proline and lysine residues in collagen synthesis, which is necessary for the stability and strength of collagen fibers. Choice B: Vitamin D is essential for bone health and calcium absorption but is not directly involved in collagen synthesis. Choice C: Vitamin B12 is important for red blood cell formation and neurological function but is not directly related to collagen synthesis. Choice D: Vitamin K is necessary for blood clotting and bone metabolism but does not play a direct role in collagen synthesis.
4. What is the function of the kidneys in the urinary system?
- A. To filter blood and remove waste
- B. To produce red blood cells
- C. To regulate blood pressure
- D. To absorb water
Correct answer: A
Rationale: The correct answer is A: 'To filter blood and remove waste.' The kidneys play a crucial role in the urinary system by filtering blood to remove waste products and excess fluids, which are then excreted as urine. This process helps maintain the body's internal balance by regulating electrolyte levels and controlling blood pressure. Choices B, C, and D are incorrect because the kidneys do not produce red blood cells (bone marrow does), regulate blood pressure directly (although they indirectly influence it through the renin-angiotensin-aldosterone system), or absorb water (they regulate water balance but do not absorb water).
5. 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.
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