HESI A2
HESI A2 Anatomy and Physiology 2023
1. Which hormone is involved in the body's stress response?
- A. Insulin
- B. Adrenaline
- C. Cortisol
- D. Melatonin
Correct answer: C
Rationale: The correct answer is C: Cortisol. Cortisol, produced by the adrenal glands, is involved in the body's stress response. It helps regulate metabolism, immune function, and the body's response to stressors by increasing blood sugar levels, suppressing the immune system, and aiding in the metabolism of fats, carbohydrates, and proteins. Choice A, Insulin, is a hormone that regulates blood sugar levels and is not primarily involved in the stress response. Choice B, Adrenaline, is also known as epinephrine and is involved in the fight-or-flight response, which is related to stress but is not the main hormone in the body's stress response. Choice D, Melatonin, is a hormone that regulates sleep-wake cycles and is not directly involved in the stress response.
2. What is the primary function of the alveoli in the lungs?
- A. Removing carbon dioxide from the blood
- B. Exchanging oxygen and carbon dioxide
- C. Transporting oxygen to the bloodstream
- D. Filtering blood
Correct answer: B
Rationale: The primary function of the alveoli in the lungs is to exchange oxygen and carbon dioxide. The alveoli are tiny air sacs in the lungs responsible for this gas exchange during breathing. Oxygen diffuses from the inhaled air into the blood in the capillaries surrounding the alveoli, while carbon dioxide diffuses from the blood into the alveoli to be exhaled out of the body. Choice A is incorrect because the alveoli primarily facilitate the exchange of gases, not just the removal of carbon dioxide. Choice C is incorrect as the alveoli do not transport oxygen to the bloodstream but rather facilitate the exchange of gases. Choice D is incorrect as the alveoli are not involved in filtering blood but in gas exchange to ensure proper oxygenation and removal of carbon dioxide in the respiratory process.
3. Which structure in the eye is responsible for focusing light on the retina?
- A. Cornea
- B. Lens
- C. Retina
- D. Pupil
Correct answer: B
Rationale: The lens of the eye is responsible for focusing light onto the retina. It plays a crucial role in bending light rays to ensure that they converge on the retina, enabling clear vision. The cornea helps in focusing light, but the final adjustment and fine-tuning occur through the lens. The retina receives the focused light and converts it into neural signals for the brain to interpret. The pupil, on the other hand, controls the amount of light entering the eye by dilating or constricting.
4. What is the main function of the nervous system?
- A. Transporting blood
- B. Protecting the body from infection
- C. Regulating body temperature
- D. Digesting food
Correct answer: C
Rationale: The main function of the nervous system is to control and coordinate body activities by transmitting signals between different parts of the body and responding to internal and external stimuli. This allows for the regulation of body temperature, movement, sensory perception, and various other functions necessary for homeostasis. Choices A, B, and D are incorrect as they do not align with the primary role of the nervous system. Transporting blood is mainly carried out by the circulatory system, protecting the body from infection is a function of the immune system, and digesting food is the role of the digestive system.
5. What are the chemical messengers that control growth, differentiation, and metabolism of specific target cells called?
- A. Hormones
- B. Neurons
- C. Glands
- D. Second messengers
Correct answer: A
Rationale: Hormones are signaling molecules produced by glands in multicellular organisms. They travel through the bloodstream to specific target cells where they regulate various physiological processes, including growth, differentiation, and metabolism. Neurons (choice B) are nerve cells that transmit nerve impulses and are not responsible for controlling growth, differentiation, or metabolism. Glands (choice C) produce and release hormones but are not the chemical messengers themselves. Second messengers (choice D) are molecules involved in intracellular signal transduction, not the primary chemical messengers controlling growth, differentiation, and metabolism. Therefore, hormones (choice A) are the correct answer as they match the description provided in the question.
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