Anatomy HESI A2 Practice Test

Correct Answer: B

Rationale: The correct answer is B: To speed up chemical reactions. Enzymes act as biological catalysts that accelerate chemical reactions by lowering the activation energy required for the reactions to occur. They do not produce energy (choice A), transport molecules (choice C), or repair tissues (choice D). Enzymes specifically facilitate reactions without being consumed in the process, making them crucial for various metabolic pathways in the body.

Correct Answer: A

Rationale: The correct answer is A: Vitamin A. Vitamin A is essential for vision as it plays a crucial role in the function of the retina and helps maintain a healthy cornea. It is also important for skin health by promoting skin cell growth and repair. Vitamin C (B) is important for immune function and collagen synthesis, not specifically for vision or skin health. Vitamin D (C) is crucial for bone health and immune function. Vitamin E (D) is an antioxidant that helps protect cells from damage, but it is not specifically essential for vision or skin health.

Correct Answer: B

Rationale: The correct answer is B: Medulla oblongata. This brain part is located in the brainstem and controls vital functions such as heart rate and blood pressure. It contains the cardiovascular center which regulates these functions through autonomic nervous system pathways. The other choices (A: Cerebellum, C: Hypothalamus, D: Pons) do not have direct control over heart rate and blood pressure regulation. The cerebellum is mainly responsible for motor coordination, the hypothalamus regulates body temperature, hunger, and thirst, and the pons is involved in sleep and arousal. Thus, the medulla oblongata is the correct choice for regulating heart rate and blood pressure.

Correct Answer: B

Rationale: The correct answer is B: To break down food. The stomach's main role in digestion is to mechanically and chemically break down food into smaller particles through the churning action of muscles and the secretion of gastric juices containing hydrochloric acid and enzymes. This process prepares the food for further digestion and absorption in the small intestine. Explanation for incorrect choices: A: To absorb nutrients - Absorption of nutrients primarily occurs in the small intestine, not the stomach. C: To secrete digestive enzymes - While the stomach does secrete digestive enzymes, its main function is to break down food, not just to secrete enzymes. D: To transport nutrients - Nutrient absorption and transportation occur in the small intestine, not the stomach.

Correct Answer: B

Rationale: The correct answer is B: Medulla oblongata. This part of the brain is located in the brainstem and is responsible for regulating essential functions like breathing and heart rate. The medulla oblongata contains centers that control autonomic functions, ensuring that these processes occur involuntarily and without conscious effort. The other choices, A (Cerebrum), C (Cerebellum), and D (Hypothalamus), are not specifically involved in regulating breathing and heart rate. The cerebrum is responsible for higher brain functions, the cerebellum is involved in coordination and balance, and the hypothalamus controls body temperature, hunger, and thirst regulation.