HESI A2
Anatomy HESI A2
1. Which organ system is primarily responsible for generating antibodies?
- A. The endocrine system
- B. The digestive system
- C. The lymphatic system
- D. The nervous system
Correct answer: C
Rationale: The correct answer is C: The lymphatic system. Antibodies are produced by specialized white blood cells called B-lymphocytes (or B cells) in response to foreign substances known as antigens. The lymphatic system includes lymph nodes, lymphatic vessels, tonsils, thymus, and spleen, which work together to produce and store antibodies to help the body fight off infections and diseases. Choice A, the endocrine system, is incorrect because it is responsible for hormone regulation, not antibody production. Choice B, the digestive system, is incorrect because its main function is to break down food and absorb nutrients, not produce antibodies. Choice D, the nervous system, is incorrect as it is responsible for transmitting signals throughout the body and coordinating body functions, not generating antibodies.
2. Which hormone is responsible for the regulation of calcium levels in the blood?
- A. Insulin
- B. Parathyroid hormone
- C. Cortisol
- D. Melatonin
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.
3. Which organ system is primarily responsible for regulating muscle growth?
- A. The skeletal system
- B. The endocrine system
- C. The nervous system
- D. The reproductive system
Correct answer: B
Rationale: The endocrine system is primarily responsible for regulating muscle growth through the production and release of hormones such as growth hormone, testosterone, and insulin-like growth factors. These hormones play crucial roles in stimulating muscle protein synthesis, increasing muscle mass, and promoting overall muscle growth and repair. The skeletal system provides structural support for muscles but does not directly regulate muscle growth. The nervous system controls muscle contractions and movements but is not primarily responsible for muscle growth. The reproductive system plays a role in fertility and secondary sexual characteristics but does not have a direct role in regulating muscle growth.
4. Where are B-lymphocytes produced?
- A. Thymus
- B. Red bone marrow
- C. Lymph nodes
- D. Spleen
Correct answer: B
Rationale: B-lymphocytes are produced in the red bone marrow. The red bone marrow is the primary site for B-cell development, where they mature before entering the circulation. The thymus is responsible for T-lymphocyte maturation, not B-lymphocytes. Lymph nodes and spleen play roles in immune responses but are not the primary sites for B-lymphocyte production.
5. Which of the following is not a principal organ of the nervous system?
- A. Brain
- B. Thymus
- C. Ganglia
- D. Spinal cord
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.
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