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. The epidermis is classified as which of the following?
- A. Cell
- B. Tissue
- C. Organ
- D. System
Correct answer: B
Rationale: The epidermis is classified as a tissue, more specifically as a layer of cells that form the outermost part of the skin. It is composed of multiple layers of cells that protect underlying tissues and regulate various functions related to the skin. Choice A, Cell, is incorrect because the epidermis is not just a single cell but rather a collection of cells. Choice C, Organ, is incorrect because the epidermis is not an organ on its own but rather a part of an organ, the skin. Choice D, System, is incorrect because the epidermis is not a system but rather a component of the integumentary system.
3. Which type of muscle is found in the walls of hollow organs?
- A. Skeletal muscle
- B. Cardiac muscle
- C. Smooth muscle
- D. Striated muscle
Correct answer: C
Rationale: Smooth muscle tissue is found in the walls of hollow organs, such as the intestines, blood vessels, and bladder. It contracts involuntarily, allowing for movements like peristalsis in the intestines and regulation of blood flow in blood vessels. Skeletal muscle (Choice A) is attached to bones and helps in voluntary movements. Cardiac muscle (Choice B) is found in the heart and contracts involuntarily to pump blood. Striated muscle (Choice D) refers to both skeletal and cardiac muscles, which have a striped appearance due to the organization of their filaments. However, smooth muscle (Choice C) is specifically the type found in hollow organs.
4. Which of the following is not part of the axial skeletal system?
- A. the skull
- B. the ribs
- C. the breastbone
- D. the radius
Correct answer: D
Rationale: The correct answer is D, the radius. The axial skeleton comprises bones located along the central axis of the body. It includes the skull, ribs, breastbone (sternum), vertebrae, and sacrum. The radius, on the other hand, is a bone of the forearm, part of the appendicular skeleton. The appendicular skeleton consists of the bones of the limbs and their girdles, not the central axial bones.
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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