Anatomy HESI A2 Practice Test

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: To store and concentrate bile. The gallbladder acts as a reservoir for bile produced by the liver, which is then released into the small intestine to aid in digestion. Bile helps emulsify fats for better absorption. Choices A, C, and D are incorrect as the gallbladder does not produce bile (the liver does), detoxify harmful substances, or directly break down fats. The primary function of the gallbladder is to store and concentrate bile for efficient digestion.

Correct Answer: C

Rationale: The function of the alveoli in the lungs is to exchange gases. Oxygen from the inhaled air diffuses into the bloodstream, while carbon dioxide from the bloodstream diffuses into the alveoli to be exhaled. This exchange process is crucial for maintaining proper oxygen levels in the blood and removing carbon dioxide, a waste product. Option A is incorrect because the alveoli do not absorb oxygen but facilitate its exchange. Option B is incorrect because while the alveoli do remove carbon dioxide, their primary function is gas exchange. Option D is incorrect as the alveoli do not regulate blood pressure but are essential for gas exchange in the respiratory system.

Correct Answer: B

Rationale: The correct answer is B: Thymus. The thymus is not a principal organ of the nervous system; it is part of the immune system. The brain (A), ganglia (C), and spinal cord (D) are all essential components of the nervous system. The brain is the main control center, ganglia are clusters of nerve cell bodies outside the central nervous system, and the spinal cord is a major pathway for transmitting nerve signals. Therefore, the thymus stands out as the only choice that is not directly related to the nervous system, making it the correct answer in this context.

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.