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. The orthopedic surgeon informs you that you have broken the middle region of the humerus. What area is he describing?
- A. Epiphysis
- B. Articular cartilage
- C. Perichondrium
- D. Diaphysis
Correct answer: D
Rationale: The diaphysis is the correct answer in this scenario. It refers to the middle or shaft region of a long bone like the humerus. The epiphysis is the end of a long bone, while articular cartilage is the smooth tissue covering the ends of bones at a joint. The perichondrium is the dense irregular connective tissue that surrounds cartilage.
3. Which type of joint is found in the knee?
- A. Ball and socket joint
- B. Hinge joint
- C. Pivot joint
- D. Saddle joint
Correct answer: B
Rationale: The correct answer is a hinge joint. The knee is a hinge joint that allows for flexion and extension movements, enabling the leg to bend and straighten. This type of joint is designed for movement along one plane, similar to a door hinge. Choice A, ball and socket joint, is incorrect as this type of joint allows for a wider range of motion in multiple directions, unlike the knee joint. Choice C, pivot joint, and Choice D, saddle joint, are also incorrect as they do not accurately describe the type of joint found in the knee.
4. What is the role of platelets in the blood?
- A. To transport oxygen
- B. To fight infections
- C. To clot blood
- D. To carry nutrients
Correct answer: C
Rationale: Platelets, also known as thrombocytes, play a crucial role in blood clotting. When there is an injury, platelets adhere to the site and release substances that form a clot, preventing excessive bleeding. This function is vital for maintaining hemostasis and preventing blood loss. Choice A is incorrect because red blood cells, not platelets, are responsible for transporting oxygen. Choice B is incorrect as white blood cells are primarily responsible for fighting infections. Choice D is incorrect as nutrients are mainly transported by plasma and red blood cells, not platelets.
5. What are the chemical messengers that control growth, differentiation, and metabolism of specific target cells called?
- A. Hormones
- B. Neurons
- C. Glands
- D. Second messengers
Correct answer: A
Rationale: Hormones are signaling molecules produced by glands in multicellular organisms. They travel through the bloodstream to specific target cells where they regulate various physiological processes, including growth, differentiation, and metabolism. Neurons (choice B) are nerve cells that transmit nerve impulses and are not responsible for controlling growth, differentiation, or metabolism. Glands (choice C) produce and release hormones but are not the chemical messengers themselves. Second messengers (choice D) are molecules involved in intracellular signal transduction, not the primary chemical messengers controlling growth, differentiation, and metabolism. Therefore, hormones (choice A) are the correct answer as they match the description provided in the question.
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