HESI A2
HESI A2 Anatomy and Physiology 2023
1. Which part of the brain is involved in the regulation of heart rate and breathing?
- A. Cerebrum
- B. Cerebellum
- C. Medulla oblongata
- D. Hypothalamus
Correct answer: C
Rationale: The correct answer is C: Medulla oblongata. The medulla oblongata, situated in the brainstem, plays a crucial role in regulating vital functions such as heart rate, breathing, and blood pressure. It serves as the control center for involuntary actions, ensuring the body's automatic functions work properly. Choices A, B, and D are incorrect because the cerebrum is primarily responsible for functions such as thinking, voluntary movements, and sensory processing; the cerebellum is involved in coordination, balance, and muscle control; and the hypothalamus regulates body temperature, thirst, hunger, and some aspects of the autonomic nervous system but not specifically heart rate and breathing.
2. What is the primary function of the liver?
- A. Detoxifying harmful substances
- B. Producing bile
- C. Producing insulin
- D. Storing glycogen
Correct answer: A
Rationale: The primary function of the liver is to detoxify harmful substances in the blood. While the liver also produces bile, which aids in digestion, stores glycogen for energy storage, and participates in metabolism, its main and essential function is detoxification. Producing insulin is mainly attributed to the pancreas, not the liver.
3. What is the main function of the skeletal system?
- A. To produce red blood cells
- B. To protect internal organs and provide support
- C. To regulate body temperature
- D. To store calcium
Correct answer: B
Rationale: The main function of the skeletal system is to provide structural support, protect internal organs, enable movement, and maintain the body's form. Choice A, 'To produce red blood cells,' is incorrect as the skeletal system's role in blood cell production is through the bone marrow, not its main function. Choice C, 'To regulate body temperature,' is incorrect as the skeletal system is not primarily responsible for regulating body temperature. Choice D, 'To store calcium,' is partially correct as the skeletal system does store calcium but this is not its main function; instead, it is essential for bone strength and muscle function.
4. Which structure is responsible for carrying oxygen to the cells?
- A. Hemoglobin
- B. Plasma
- C. Platelets
- D. Red blood cells
Correct answer: A
Rationale: Hemoglobin, located in red blood cells, is responsible for binding to oxygen in the lungs and transporting it to tissues throughout the body. Red blood cells contain hemoglobin, making them the primary carrier of oxygen to cells. Hemoglobin is the correct answer because it is the protein within red blood cells that directly binds to oxygen for transport. Plasma is the liquid component of blood and does not carry oxygen. Platelets are responsible for blood clotting and have no role in oxygen transport. While red blood cells do carry oxygen, it is specifically the hemoglobin within them that performs this function.
5. Which of the following is not part of the body’s secondary defense system?
- A. Macrophages
- B. Leukocytes
- C. T cells
- D. Cilia
Correct answer: D
Rationale: Cilia are not part of the body's secondary defense system. They are hair-like structures primarily involved in movement and transporting substances across cell surfaces, such as in the respiratory tract for debris and pathogen removal. However, cilia do not play a direct role in the immune response mechanisms characteristic of the body's secondary defense system. Macrophages, leukocytes, and T cells are immune cells that actively participate in the secondary defense system by targeting and eliminating pathogens.
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