HESI A2
HESI A2 Practice Test Anatomy and Physiology
1. 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.
2. What is the primary function of the respiratory system?
- A. To absorb oxygen
- B. To transport nutrients
- C. To produce sound and speech
- D. To regulate blood pressure
Correct answer: A
Rationale: The primary function of the respiratory system is to absorb oxygen from the air into the bloodstream and expel carbon dioxide from the body. This process is essential for cellular respiration and the production of energy in the body. Option A, 'To absorb oxygen,' aligns with this crucial function, making it the correct choice. Choices B, C, and D are incorrect as they do not represent the primary function of the respiratory system. The respiratory system is not responsible for transporting nutrients (choice B), producing sound and speech (choice C), or regulating blood pressure (choice D).
3. What is the main component of the cell membrane?
- A. Proteins
- B. Carbohydrates
- C. Lipids
- D. Nucleic acids
Correct answer: C
Rationale: The main component of the cell membrane is the phospholipid bilayer, which is primarily composed of lipids. Lipids form a barrier that separates the interior of the cell from the external environment, providing structural integrity and regulating the passage of substances in and out of the cell. Proteins are also essential components of the cell membrane, serving various functions such as transport, signaling, and cell recognition. Carbohydrates are present in the form of glycoproteins and glycolipids on the cell membrane surface, contributing to cell-cell recognition. Nucleic acids are not a primary component of the cell membrane.
4. Where do nearly all of the gaseous exchanges between air and blood take place in the lungs?
- A. Pleura
- B. Trachea
- C. Bronchioles
- D. Alveoli
Correct answer: D
Rationale: Nearly all gaseous exchanges between air and blood take place in the alveoli of the lungs. The walls of the alveoli are thin and surrounded by an extensive network of tiny blood vessels called capillaries. Oxygen from the air diffuses through the alveoli walls and into the bloodstream, while carbon dioxide, a waste product, diffuses from the blood into the alveoli to be exhaled out of the body. This process is essential for respiration and providing oxygen to the body's cells. Choices A, B, and C are incorrect. Pleura is the membrane surrounding the lungs, trachea is the windpipe that carries air to the lungs, and bronchioles are the smaller air passages in the lungs. However, the primary site for gaseous exchange is the alveoli due to their structure and function.
5. The sebaceous glands are part of which system?
- A. Endocrine system
- B. Digestive system
- C. Respiratory system
- D. Integumentary system
Correct answer: D
Rationale: The sebaceous glands are a component of the integumentary system, which includes the skin, hair, nails, and associated structures. Sebaceous glands are typically found throughout the skin and are responsible for producing an oily substance called sebum, which helps keep the skin and hair lubricated and moisturized. The endocrine system (Choice A) consists of glands that produce hormones, the digestive system (Choice B) is responsible for processing food, and the respiratory system (Choice C) is involved in breathing and gas exchange.
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