what is the main function of the immune system
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HESI A2

Anatomy and Physiology Hesi A2 Practice Test

1. What is the main function of the immune system?

Correct answer: B

Rationale: The main function of the immune system is to protect the body from infections by identifying and destroying pathogens like bacteria and viruses. It plays a crucial role in maintaining overall health and preventing illnesses. Choice A is incorrect because hormone production is primarily handled by the endocrine system, not the immune system. Choice C is incorrect as waste removal is mainly performed by the excretory system, not the immune system. Choice D is incorrect as regulating body temperature is primarily the role of the thermoregulatory system, not the immune system.

2. Which of the following is true about skeletal muscle?

Correct answer: B

Rationale: The correct statement is that skeletal muscle attaches to bones through tendons, enabling movement. Tendons connect muscles to bones and allow the force generated by muscle contraction to be transmitted to the bones, facilitating voluntary movements. Choice A is incorrect because skeletal muscle typically makes up around 40-50% of an individual's body weight, not a fixed 40%. Choice C is incorrect as muscle contraction plays a vital role in temperature regulation by generating heat. Choice D is incorrect as skeletal muscles may have constant low-level contractions even at rest, known as muscle tone.

3. Which hormone is involved in the regulation of water balance in the body?

Correct answer: A

Rationale: The correct answer is ADH (antidiuretic hormone), also known as vasopressin. ADH helps regulate water balance in the body by controlling the amount of water reabsorbed by the kidneys. When there is a need to conserve water, ADH levels increase, leading to more water reabsorption and concentration of urine. Insulin is involved in regulating blood sugar levels, not water balance. Cortisol is a stress hormone that helps regulate metabolism and immune response, not water balance. Thyroxine is a thyroid hormone that regulates metabolism, growth, and development, not water balance.

4. Which gland produces hormones that regulate sleep?

Correct answer: B

Rationale: The pineal gland secretes melatonin, a hormone that plays a crucial role in regulating the sleep-wake cycle. Melatonin production is influenced by exposure to light, with levels increasing in the evening to promote sleep and decreasing in the morning to signal wakefulness. Choices A, C, and D are incorrect because the thyroid gland primarily regulates metabolism, the adrenal gland produces hormones like adrenaline and cortisol related to stress response, and the pituitary gland controls various functions by releasing different hormones but not specifically related to regulating sleep.

5. Which type of blood vessel carries blood away from the heart?

Correct answer: B

Rationale: Arteries are blood vessels that carry oxygenated blood away from the heart to the rest of the body. They have thick, muscular walls to withstand the high pressure generated by the heart's contractions, ensuring efficient transport of blood throughout the body. Veins, on the other hand, carry deoxygenated blood back to the heart, while capillaries facilitate the exchange of nutrients, oxygen, and waste products between the blood and tissues. Nerves are not involved in the transport of blood.

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