HESI A2
HESI A2 Anatomy and Physiology Practice Exam
1. The anterior chamber of the eye lies between the ___________.
- A. iris and lens
- B. lens and retina
- C. cornea and iris
- D. retina and optic nerve
Correct answer: A
Rationale: The anterior chamber of the eye is the fluid-filled space located between the cornea and the iris in the front part of the eye. It contains aqueous humor and helps maintain intraocular pressure. The space between the iris and the lens is known as the anterior chamber, making option A, 'iris and lens,' the correct choice. Options B, C, and D are incorrect because they do not describe the correct anatomical location of the anterior chamber.
2. Which vitamin is essential for the clotting of blood?
- A. Vitamin A
- B. Vitamin K
- C. Vitamin C
- D. Vitamin D
Correct answer: B
Rationale: Vitamin K is essential for the synthesis of proteins required for blood clotting. It specifically assists in the activation of clotting factors to prevent excessive bleeding from injuries. Vitamin K plays a crucial role in maintaining a balance between clotting and bleeding in the body. Choices A, C, and D are incorrect. Vitamin A is important for vision, immune function, and skin health. Vitamin C is essential for collagen synthesis and acts as an antioxidant. Vitamin D is crucial for calcium absorption and bone health.
3. What is the function of white blood cells?
- A. To carry oxygen to the cells
- B. To fight infection
- C. To transport nutrients
- D. To clot blood
Correct answer: B
Rationale: White blood cells are a vital part of the immune system. Their primary function is to fight infections by attacking bacteria, viruses, and other pathogens that enter the body. They play a crucial role in protecting the body against illnesses and maintaining overall health. Choice A is incorrect because the role of carrying oxygen to cells is primarily performed by red blood cells. Choice C is incorrect as the transportation of nutrients is mainly carried out by the bloodstream and specialized cells. Choice D is incorrect as the process of clotting blood is primarily mediated by platelets.
4. 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.
5. Which part of the brain is responsible for regulating body temperature?
- A. Cerebrum
- B. Cerebellum
- C. Brainstem
- D. Hypothalamus
Correct answer: D
Rationale: The hypothalamus is the part of the brain responsible for regulating body temperature, along with controlling other autonomic functions like hunger, thirst, and sleep. It acts as the body's internal thermostat, helping to maintain a stable internal environment despite external temperature changes. The cerebrum is mainly associated with functions like thinking, perception, and voluntary movements, making it unrelated to regulating body temperature. The cerebellum is involved in coordination and balance, not in regulating body temperature. The brainstem is essential for basic life functions like breathing and heart rate, but it is not primarily responsible for regulating body temperature.
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