HESI A2
HESI A2 Anatomy and Physiology 2023
1. Which part of the brain is involved in the regulation of heart rate and breathing?
- A. Cerebrum
- B. Cerebellum
- C. Medulla oblongata
- D. Hypothalamus
Correct answer: C
Rationale: The correct answer is C: Medulla oblongata. The medulla oblongata, situated in the brainstem, plays a crucial role in regulating vital functions such as heart rate, breathing, and blood pressure. It serves as the control center for involuntary actions, ensuring the body's automatic functions work properly. Choices A, B, and D are incorrect because the cerebrum is primarily responsible for functions such as thinking, voluntary movements, and sensory processing; the cerebellum is involved in coordination, balance, and muscle control; and the hypothalamus regulates body temperature, thirst, hunger, and some aspects of the autonomic nervous system but not specifically heart rate and breathing.
2. What is the function of white blood cells?
- A. To carry oxygen to the cells
- B. To fight infection
- C. To transport nutrients
- D. To clot blood
Correct answer: B
Rationale: White blood cells are a vital part of the immune system. Their primary function is to fight infections by attacking bacteria, viruses, and other pathogens that enter the body. They play a crucial role in protecting the body against illnesses and maintaining overall health. Choice A is incorrect because the role of carrying oxygen to cells is primarily performed by red blood cells. Choice C is incorrect as the transportation of nutrients is mainly carried out by the bloodstream and specialized cells. Choice D is incorrect as the process of clotting blood is primarily mediated by platelets.
3. Which structure in the eye is responsible for focusing light on the retina?
- A. Cornea
- B. Lens
- C. Retina
- D. Pupil
Correct answer: B
Rationale: The lens of the eye is responsible for focusing light onto the retina. It plays a crucial role in bending light rays to ensure that they converge on the retina, enabling clear vision. The cornea helps in focusing light, but the final adjustment and fine-tuning occur through the lens. The retina receives the focused light and converts it into neural signals for the brain to interpret. The pupil, on the other hand, controls the amount of light entering the eye by dilating or constricting.
4. Which type of muscle is under voluntary control?
- A. Smooth muscle
- B. Cardiac muscle
- C. Skeletal muscle
- D. Striated muscle
Correct answer: C
Rationale: The correct answer is C: Skeletal muscle. Skeletal muscle is under voluntary control, allowing individuals to consciously regulate its contractions for movement. Examples of skeletal muscle control include actions like walking, running, and lifting weights. Smooth muscle (choice A) and cardiac muscle (choice B) are both involuntary muscles, meaning they are not under conscious control. While skeletal muscle is striated (choice D), striated muscle is a broader category that includes both voluntary (skeletal) and involuntary (cardiac) muscles.
5. Which is a posterior feature of the human leg?
- A. Patella
- B. Quadriceps sartorius
- C. Triceps brachii
- D. Achilles tendon
Correct answer: D
Rationale: The correct answer is the Achilles tendon. The Achilles tendon is a strong tendon located at the back of the human leg, connecting the calf muscles to the heel bone. This positioning makes it a posterior feature, situated at the rear of the leg. The patella, also known as the kneecap, is positioned at the front of the leg, making it an anterior feature. The quadriceps sartorius are muscles located in the front of the thigh, not at the back of the leg. Additionally, the triceps brachii is a muscle found in the upper arm, not in the leg, making it an incorrect choice.
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