HESI A2
HESI A2 Practice Test Anatomy and Physiology
1. Which type of blood cell is involved in clotting?
- A. Red blood cells
- B. White blood cells
- C. Platelets
- D. Plasma
Correct answer: C
Rationale: Platelets, also known as thrombocytes, are cell fragments that play a crucial role in blood clotting and wound healing. They are responsible for forming blood clots to stop bleeding when a blood vessel is injured, making them the correct choice in this context. Red blood cells (Choice A) are primarily involved in oxygen transport, white blood cells (Choice B) are part of the immune system, and plasma (Choice D) is the liquid component of blood that carries various substances.
2. What is the name of the outermost layer of the skin?
- A. dermis
- B. epidermis
- C. subcutaneous tissue
- D. hypodermis
Correct answer: B
Rationale: The epidermis is the correct answer as it is the outermost layer of the skin. It acts as a protective barrier against environmental factors and helps in regulating moisture balance. The epidermis is also where new skin cells are continuously formed and contains melanocytes responsible for skin pigmentation. Choices A, C, and D are incorrect. The dermis is the layer beneath the epidermis, the subcutaneous tissue is the deepest layer of the skin, and the hypodermis lies below the dermis.
3. Which structure in the ear is responsible for balance?
- A. Cochlea
- B. Semicircular canals
- C. Ossicles
- D. Eustachian tube
Correct answer: B
Rationale: The semicircular canals in the inner ear are responsible for maintaining balance by detecting changes in head position and movement. These structures contain fluid and hair cells that send signals to the brain regarding the body's orientation in space, helping us stay balanced and navigate our surroundings. The cochlea is responsible for hearing, the ossicles are involved in sound transmission, and the Eustachian tube helps equalize pressure in the middle ear, but they are not directly related to balance.
4. 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.
5. Which type of blood cell is primarily responsible for fighting infections?
- A. Red blood cells
- B. White blood cells
- C. Platelets
- D. Plasma
Correct answer: B
Rationale: White blood cells, also known as leukocytes, play a crucial role in the immune system by primarily combating infections. These cells can identify and destroy pathogens, such as bacteria and viruses, helping the body defend against illnesses and maintain overall health. Red blood cells are responsible for oxygen transport, platelets aid in blood clotting, and plasma carries various components throughout the circulatory system, but none of these functions involve fighting infections like white blood cells do.
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