HESI A2
HESI A2 Anatomy and Physiology 2023
1. Which structure in the ear is responsible for detecting sound?
- A. Cochlea
- B. Eustachian tube
- C. Ossicles
- D. Semicircular canals
Correct answer: A
Rationale: The cochlea, situated in the inner ear, is responsible for detecting sound waves and converting them into neural signals that are transmitted to the brain for processing. The cochlea contains specialized sensory cells that respond to different frequencies of sound, allowing us to hear a wide range of sounds. The other structures listed, such as the eustachian tube, ossicles, and semicircular canals, play roles in functions like equalizing pressure, transmitting vibrations, and maintaining balance, respectively, but they are not directly involved in the detection of sound.
2. Which part of the brain controls balance and coordination?
- A. Cerebellum
- B. Cerebrum
- C. Medulla oblongata
- D. Brainstem
Correct answer: A
Rationale: The correct answer is the cerebellum. Located at the back of the brain, the cerebellum plays a crucial role in controlling balance, coordination, and fine motor movements. It receives information from the sensory systems, the spinal cord, and other parts of the brain to coordinate voluntary movements and maintain posture. Damage to the cerebellum can result in issues with balance, coordination, and muscle tone. The cerebrum is responsible for higher brain functions like thinking and problem-solving, the medulla oblongata controls vital autonomic functions like breathing and heartbeat, and the brainstem serves as a pathway for neural fibers traveling to and from the brain.
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. How might the headrest on a car prevent traumatic injury?
- A. By limiting hyperflexion of the neck
- B. By limiting hyperextension of the neck
- C. By reducing vertebral compression
- D. By preventing disc degeneration
Correct answer: B
Rationale: The headrest on a car is designed to prevent traumatic injury by limiting hyperextension of the neck during a rear-end collision. This helps reduce the risk of whiplash and other neck injuries that may occur when the head is forcefully thrown backward. Choice A is incorrect because hyperflexion is not the primary concern in rear-end collisions. Choice C is incorrect as the headrest does not directly reduce vertebral compression. Choice D is incorrect because the headrest is not directly involved in preventing disc degeneration.
5. Which hormone is involved in the fight or flight response?
- A. Cortisol
- B. Adrenaline
- C. Thyroxine
- D. Melatonin
Correct answer: B
Rationale: The correct answer is B: Adrenaline. Adrenaline, also known as epinephrine, is the hormone involved in the fight or flight response. It is released by the adrenal glands, preparing the body for action by increasing heart rate, dilating airways, and mobilizing energy stores. Choice A, Cortisol, is a hormone released in response to stress but is not directly involved in the fight or flight response. Choice C, Thyroxine, is a hormone produced by the thyroid gland that regulates metabolism and growth, not specifically associated with the fight or flight response. Choice D, Melatonin, is a hormone that regulates sleep-wake cycles and is not involved in the fight or flight response.
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