HESI A2
HESI A2 Anatomy and Physiology 2023
1. Which part of the eye is responsible for color vision?
- A. Cornea
- B. Iris
- C. Retina
- D. Lens
Correct answer: C
Rationale: The correct answer is option C: Retina. The retina contains photoreceptor cells, including cones that are responsible for color vision. Cones are sensitive to different wavelengths of light, allowing us to perceive and differentiate various colors. Choice A, Cornea, is the transparent outer layer of the eye that helps focus light. It does not play a direct role in color vision. Choice B, Iris, is the colored part of the eye that controls the size of the pupil and regulates the amount of light entering the eye. While it is essential for adjusting light levels, it is not directly involved in color vision. Choice D, Lens, is responsible for focusing light onto the retina. It helps to form clear images on the retina but does not play a role in color vision.
2. A person who has damage to their ulnar nerve will have decreased sensation in which part of the body?
- A. Hand
- B. Arm
- C. Leg
- D. Foot
Correct answer: A
Rationale: Corrected Rationale: Damage to the ulnar nerve typically results in decreased sensation in the hand, particularly affecting the little finger and half of the ring finger. The ulnar nerve innervates the hand and is responsible for providing sensation to these areas. This nerve does not extend to the leg or foot, so choices C and D are incorrect. While the ulnar nerve travels through the arm, its primary sensory impact is felt in the hand, making choice B less specific and therefore not the best answer.
3. Which part of the brain controls breathing and heart rate?
- A. Cerebrum
- B. Medulla oblongata
- C. Cerebellum
- D. Hypothalamus
Correct answer: B
Rationale: The medulla oblongata, located in the brainstem, plays a crucial role in controlling vital functions such as breathing, heart rate, and blood pressure. It serves as the control center for automatic functions necessary for survival, making it the correct choice in this scenario. The cerebrum is responsible for higher brain functions like thinking and voluntary movements, so it does not control basic physiological functions like breathing and heart rate. The cerebellum is mainly involved in coordination and balance, while the hypothalamus regulates body temperature, hunger, and thirst, but not specifically breathing and heart rate.
4. What is the meaning of exocytosis?
- A. The cell engulfs and brings in substances.
- B. The cell releases content outside by fusing with the plasma membrane.
- C. The cell engulfs liquid material.
- D. The cell brings in solid particles.
Correct answer: B
Rationale: Exocytosis is the process by which a cell releases substances to the outside by fusing with the plasma membrane. During exocytosis, vesicles containing molecules fuse with the cell membrane, allowing the release of the contents outside the cell. This process is crucial for the secretion of various substances such as hormones, enzymes, and neurotransmitters. Choices A, C, and D are incorrect as they describe processes different from exocytosis. Choice A describes endocytosis, where the cell engulfs substances to bring them into the cell. Choice C is more aligned with pinocytosis, the process of engulfing liquid material. Choice D refers to phagocytosis, which is the uptake of solid particles by the cell.
5. Which organ system is primarily responsible for generating antibodies?
- A. The endocrine system
- B. The digestive system
- C. The lymphatic system
- D. The nervous system
Correct answer: C
Rationale: The correct answer is C: The lymphatic system. Antibodies are produced by specialized white blood cells called B-lymphocytes (or B cells) in response to foreign substances known as antigens. The lymphatic system includes lymph nodes, lymphatic vessels, tonsils, thymus, and spleen, which work together to produce and store antibodies to help the body fight off infections and diseases. Choice A, the endocrine system, is incorrect because it is responsible for hormone regulation, not antibody production. Choice B, the digestive system, is incorrect because its main function is to break down food and absorb nutrients, not produce antibodies. Choice D, the nervous system, is incorrect as it is responsible for transmitting signals throughout the body and coordinating body functions, not generating antibodies.
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