HESI A2
HESI A2 Anatomy and Physiology Quizlet
1. Which structure in the brain is involved in regulating body temperature?
- A. Cerebellum
- B. Hypothalamus
- C. Medulla oblongata
- D. Pineal gland
Correct answer: B
Rationale: The correct answer is B, the Hypothalamus. The hypothalamus plays a crucial role in regulating body temperature, hunger, thirst, and other autonomic functions, aiding in the maintenance of homeostasis within the body. It acts as the body's thermostat, responding to internal and external temperature changes to keep the body within a narrow temperature range. Choices A, C, and D are incorrect. The cerebellum is mainly involved in coordinating voluntary movements and balance. The medulla oblongata controls vital functions such as heartbeat and breathing. The pineal gland is responsible for producing melatonin, which regulates sleep-wake cycles.
2. 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.
3. Which structure in the eye focuses light onto the retina?
- A. Cornea
- B. Lens
- C. Pupil
- D. Iris
Correct answer: B
Rationale: The lens of the eye is responsible for focusing light onto the retina. It plays a crucial role in adjusting the focus to allow for clear vision. After the light passes through the lens, it reaches the retina where it is converted into neural signals for the brain to interpret. The cornea is the transparent outer layer of the eye that helps in focusing light, but its main function is to protect the eye. The pupil is the opening in the center of the iris that regulates the amount of light entering the eye. The iris is the colored part of the eye that controls the size of the pupil.
4. Which of the following processes represents a different level of defense compared to the others?
- A. A low pH in the stomach
- B. Cilia present in the trachea
- C. Body cells recognizing a pathogen
- D. Mucus present in the nasal cavity
Correct answer: C
Rationale: Among the listed processes, low pH in the stomach, cilia in the trachea, and mucus in the nasal cavity serve as physical barriers that form the first line of defense against pathogens. These barriers work to block pathogens from entering the body. On the other hand, body cells recognizing a pathogen involves the immune response, which operates at a different level of defense. This process is part of the adaptive immune response, where the body's immune cells identify, target, and eliminate specific pathogens to provide a specialized defense after the pathogens have breached the physical barriers. Therefore, body cells recognizing a pathogen represent a different level of defense compared to the other listed processes.
5. What is the normal pH of human arterial blood?
- A. 6.8
- B. 7.4
- C. 7.9
- D. 8.2
Correct answer: B
Rationale: The normal pH of human arterial blood is approximately 7.4. This slightly alkaline pH is crucial for the proper functioning of enzymes and biochemical processes in the body. Any significant deviation from this pH level can result in serious health issues such as acidosis or alkalosis. Choice A (6.8) is incorrect as it is lower than the normal pH of arterial blood, indicating acidity. Choice C (7.9) and Choice D (8.2) are incorrect as they are higher than the normal pH of arterial blood, indicating alkalinity.
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