which mineral is considered an antioxidant
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HESI A2

HESI A2 Anatomy and Physiology Practice Exam

1. Which mineral is considered an antioxidant?

Correct answer: A

Rationale: Selenium is the correct answer. It is considered an antioxidant mineral that plays a crucial role in protecting cells from damage caused by free radicals. Selenium is an essential component of the body's antioxidant defense system, promoting overall health and well-being. Calcium (Choice B), Sulfur (Choice C), and Iron (Choice D) are not typically classified as antioxidant minerals. While these minerals have other important functions in the body, they do not primarily act as antioxidants like selenium.

2. Which of the following is not a principal organ of the nervous system?

Correct answer: B

Rationale: The correct answer is B. The thymus is not a principal organ of the nervous system; it is part of the immune system. The brain, spinal cord, and ganglia are principal organs of the nervous system. The brain is responsible for processing information, the spinal cord helps transmit signals between the brain and the rest of the body, and ganglia are clusters of nerve cells that support the nervous system's functions. Therefore, the thymus is the correct answer as it is not directly involved in nervous system functions.

3. Which hormone is responsible for the regulation of calcium levels in the blood?

Correct answer: B

Rationale: Parathyroid hormone, produced by the parathyroid glands, is responsible for regulating calcium levels in the blood. It achieves this by increasing calcium absorption in the intestines and kidneys, thus maintaining appropriate calcium levels in the bloodstream. Insulin is involved in glucose metabolism, not calcium regulation. Cortisol is a stress hormone that affects various body functions but not calcium levels. Melatonin is responsible for regulating the sleep-wake cycle, not calcium levels.

4. Which part of the brain is involved in the regulation of heart rate and breathing?

Correct answer: C

Rationale: The correct answer is C: Medulla oblongata. The medulla oblongata, situated in the brainstem, plays a crucial role in regulating vital functions such as heart rate, breathing, and blood pressure. It serves as the control center for involuntary actions, ensuring the body's automatic functions work properly. Choices A, B, and D are incorrect because the cerebrum is primarily responsible for functions such as thinking, voluntary movements, and sensory processing; the cerebellum is involved in coordination, balance, and muscle control; and the hypothalamus regulates body temperature, thirst, hunger, and some aspects of the autonomic nervous system but not specifically heart rate and breathing.

5. What is the primary function of the respiratory system?

Correct answer: A

Rationale: The primary function of the respiratory system is to facilitate the exchange of oxygen and carbon dioxide between the air and the bloodstream. Oxygen is taken in during inhalation and transported to cells, while carbon dioxide is removed during exhalation as a waste product of cellular metabolism. Choices B, C, and D are incorrect as they do not reflect the primary function of the respiratory system. Regulating body temperature is mainly controlled by the thermoregulatory system, fighting infections is a function of the immune system, and producing energy is primarily done by the metabolic system.

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