Quizlet HESI A2 Anatomy and Physiology

Correct Answer: A

Rationale: The primary role of hemoglobin in red blood cells is to carry oxygen. Hemoglobin binds to oxygen in the lungs and transports it to tissues throughout the body. This is essential for cellular respiration and energy production. Choices B, C, and D are incorrect because hemoglobin's main function is oxygen transport, not carrying nutrients, carbon dioxide, or waste products. Oxygen transport is crucial for the body's overall function and survival.

Correct Answer: C

Rationale: The correct answer is C: Vitamin D. Vitamin D is essential for calcium absorption in the intestines by promoting the production of proteins that transport calcium. Without sufficient Vitamin D, the body cannot effectively absorb calcium, leading to potential bone and muscle weakness. Choice A: Vitamin A is not directly involved in calcium absorption. Choice B: Vitamin C is important for collagen synthesis and immune function but does not play a significant role in calcium absorption. Choice D: Vitamin K is primarily involved in blood clotting and bone health but does not directly affect calcium absorption.

Correct Answer: B

Rationale: The correct answer is B: To protect the body from external damage. The skin acts as a physical barrier, preventing harmful substances from entering the body and protecting internal organs. It also helps regulate body temperature to some extent, but that is not its primary function. The skin does not produce vitamin D; this is mainly done by the liver and kidneys. Red blood cells are produced in the bone marrow, not the skin.

Correct Answer: B

Rationale: The correct answer is B. The main function of the endocrine system is to regulate body functions through hormones. Hormones are chemical messengers that travel through the bloodstream to target organs and tissues, influencing processes such as metabolism, growth, and reproduction. Choice A (To fight infections) is incorrect because the immune system is primarily responsible for fighting infections. Choice C (To produce red blood cells) is incorrect as the production of red blood cells is primarily controlled by the hormone erythropoietin, which is produced by the kidneys. Choice D (To transport oxygen) is incorrect as the transportation of oxygen is mainly carried out by the respiratory and circulatory systems, not the endocrine system.

Correct Answer: B

Rationale: The primary function of the respiratory system is to transport oxygen to the cells. Oxygen is crucial for cellular respiration, which produces energy for the body. The respiratory system accomplishes this through breathing, where oxygen is inhaled and transported via the bloodstream to cells. Removing carbon dioxide (choice A) is an important secondary function. Delivering nutrients (choice C) is the role of the circulatory system. Creating sound and speech (choice D) is the function of the larynx and vocal cords, not the entire respiratory system.