HESI A2
HESI A2 Practice Test Anatomy and Physiology
1. Which of the following structures regulates the transport of substances in and out of a cell?
- A. Nucleus
- B. Cell membrane
- C. Cytoplasm
- D. Mitochondria
Correct answer: B
Rationale: The cell membrane, also known as the plasma membrane, is responsible for regulating the transport of substances in and out of the cell. It acts as a selective barrier, allowing the passage of certain molecules while restricting others. This selective permeability helps maintain homeostasis within the cell by controlling the movement of essential substances like nutrients and waste products. The nucleus (Choice A) is the organelle that houses the cell's genetic material and is not directly involved in regulating substance transport. Cytoplasm (Choice C) is the gel-like substance that fills the cell and does not play a direct role in regulating substance transport. Mitochondria (Choice D) are responsible for energy production in the cell through cellular respiration and are not primarily involved in substance transport.
2. Which brain structure is responsible for regulating hunger and thirst?
- A. Hypothalamus
- B. Cerebellum
- C. Medulla oblongata
- D. Cerebrum
Correct answer: A
Rationale: The correct answer is the hypothalamus. This brain structure plays a crucial role in regulating hunger, thirst, body temperature, and various autonomic functions. The hypothalamus is responsible for maintaining homeostasis by responding to sensory signals and releasing appropriate hormones to control these essential physiological processes. The cerebellum (Choice B) is primarily involved in coordinating movement and balance, not hunger and thirst. The medulla oblongata (Choice C) is responsible for regulating vital autonomic functions such as breathing and heartbeat, but not hunger and thirst. The cerebrum (Choice D) is involved in higher brain functions such as thinking, decision-making, and processing sensory information, but it is not primarily responsible for regulating hunger and thirst.
3. What is the primary function of the pancreas in digestion?
- A. To absorb nutrients
- B. To secrete digestive enzymes
- C. To produce bile
- D. To store glucose
Correct answer: B
Rationale: The correct answer is B: To secrete digestive enzymes. The pancreas plays a crucial role in digestion by secreting digestive enzymes that break down carbohydrates, fats, and proteins in the small intestine. These enzymes help in the process of breaking down food particles into smaller molecules that can be easily absorbed by the body for nutrients. Choices A, C, and D are incorrect as the primary function of the pancreas is not to absorb nutrients, produce bile, or store glucose in digestion.
4. Which gland produces the hormone melatonin?
- A. Pineal gland
- B. Thyroid gland
- C. Pituitary gland
- D. Adrenal gland
Correct answer: A
Rationale: The correct answer is the Pineal gland. The pineal gland is responsible for producing melatonin, a hormone that helps regulate the sleep-wake cycle. Melatonin secretion is influenced by light exposure. Higher levels are observed at night to promote sleep, while lower levels during the day encourage wakefulness. Choices B, C, and D are incorrect as they are not associated with the production of melatonin. The thyroid gland produces hormones like thyroxine and triiodothyronine, the pituitary gland controls various other glands, and the adrenal gland produces hormones like adrenaline and cortisol.
5. 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.
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