HESI A2
HESI A2 Anatomy and Physiology Practice Test 2023
1. 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.
2. 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.
3. Which of the following is the largest organ in the human body?
- A. Liver
- B. Skin
- C. Brain
- D. Heart
Correct answer: B
Rationale: The skin is the largest organ in the human body. It serves as a protective barrier against the environment, regulates temperature, and provides sensory information. The liver, brain, and heart are vital organs, but they are not as extensive as the skin. The liver is primarily responsible for detoxification and metabolism. The brain is the control center of the body, coordinating various functions. The heart is a crucial organ that pumps blood throughout the body. However, in terms of size, the skin surpasses all of these organs.
4. How do the intercostal muscles between the ribs assist with respiration?
- A. By protecting the delicate bronchioles and alveoli
- B. By signaling a decrease in intra-alveolar pressure
- C. By enlarging and reducing the space in the thorax
- D. By maintaining a medial separation between pleurae
Correct answer: C
Rationale: The intercostal muscles located between the ribs play a crucial role in respiration by aiding in the enlargement and reduction of the space in the thorax. During inspiration, these muscles contract, lifting the rib cage, which increases the volume of the thoracic cavity and allows the lungs to expand and fill with air. This process directly relates to the expansion of the thorax rather than protecting bronchioles and alveoli (Choice A), signaling intra-alveolar pressure changes (Choice B), or maintaining the separation between pleurae (Choice D). Therefore, the correct answer is C.
5. What is the primary function of platelets in the blood?
- A. To carry oxygen
- B. To fight infections
- C. To clot blood
- D. To transport nutrients
Correct answer: C
Rationale: The correct answer is C: To clot blood. Platelets, also known as thrombocytes, have a primary function in blood clotting. They help in the process of coagulation, forming clots to prevent excessive bleeding when injuries occur. Platelets play a crucial role in maintaining the integrity of the circulatory system by sealing off damaged blood vessels and promoting wound healing. Choices A, B, and D are incorrect because platelets do not carry oxygen, fight infections, or transport nutrients in the blood.
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