HESI A2
Anatomy HESI A2
1. Which hormone stimulates milk production in the breasts during lactation?
- A. norepinephrine
- B. antidiuretic hormone
- C. prolactin
- D. oxytocin
Correct answer: C
Rationale: During lactation, the hormone responsible for stimulating milk production in the breasts is 'prolactin.' Prolactin plays a crucial role in initiating and maintaining lactation by promoting the development of alveoli in the mammary glands and stimulating milk synthesis. While oxytocin is involved in the ejection of milk from the breasts, it is prolactin that primarily governs milk production. Norepinephrine is not directly involved in milk production, and antidiuretic hormone primarily regulates water balance and blood pressure, not milk production.
2. Which gland is known as the 'master gland'?
- A. Thyroid gland
- B. Pituitary gland
- C. Adrenal gland
- D. Pineal gland
Correct answer: B
Rationale: The pituitary gland, often referred to as the 'master gland,' is the correct answer. It is responsible for regulating the release of hormones from other endocrine glands in the body. The pituitary gland controls various bodily functions and plays a crucial role in maintaining hormonal balance, making it a central and vital component of the endocrine system. The other options, such as the thyroid gland (A), adrenal gland (C), and pineal gland (D), have important functions in the endocrine system but are not specifically known as the 'master gland.'
3. What is the primary function of the skeletal system?
- A. To produce blood cells
- B. To protect organs
- C. To store fat
- D. To secrete hormones
Correct answer: B
Rationale: The primary function of the skeletal system is to protect vital organs, provide structural support, and enable movement. It serves as a framework that supports and protects internal organs, such as the brain, heart, and lungs. Choice A is incorrect because blood cell production primarily occurs in the bone marrow, a component of the skeletal system but not its primary function. Choice C is incorrect because fat storage is not a primary function of the skeletal system. Choice D is incorrect because hormone secretion is mainly regulated by endocrine glands, not the skeletal system.
4. Which type of blood cell is responsible for carrying oxygen?
- A. Red blood cells
- B. White blood cells
- C. Platelets
- D. Plasma cells
Correct answer: A
Rationale: The correct answer is A: Red blood cells. Red blood cells, also known as erythrocytes, are specialized cells designed to transport oxygen from the lungs to tissues and organs throughout the body. These cells contain hemoglobin, a protein that binds to oxygen molecules in the lungs and releases them in other parts of the body where oxygen is needed for cellular respiration. White blood cells (choice B) are part of the immune system, responsible for fighting infections. Platelets (choice C) are involved in blood clotting. Plasma cells (choice D) are a type of white blood cell that produces antibodies to help the body fight off infections.
5. Which hormone is involved in regulating the sleep-wake cycle?
- A. Insulin
- B. Melatonin
- C. Cortisol
- D. Thyroxine
Correct answer: B
Rationale: The correct answer is B: Melatonin. Melatonin, produced by the pineal gland, is the hormone involved in regulating the sleep-wake cycle. It plays a crucial role in signaling the body that it is time to sleep and is influenced by light exposure. Melatonin levels typically rise in the evening, promoting sleep, and decrease in the morning, helping in waking up. Choice A, Insulin, is involved in regulating blood sugar levels, not the sleep-wake cycle. Choice C, Cortisol, is a stress hormone that helps regulate metabolism and immune response but is not primarily involved in the sleep-wake cycle. Choice D, Thyroxine, is a hormone produced by the thyroid gland that regulates metabolism, growth, and development, but it is not directly involved in regulating the sleep-wake cycle.
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