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 primary function of the alveoli in the lungs is to exchange oxygen and carbon dioxide. This process occurs through diffusion, where oxygen moves from the alveoli into the bloodstream, and carbon dioxide moves from the bloodstream into the alveoli to be exhaled. This exchange is essential for oxygenating the blood and removing carbon dioxide, maintaining proper gas exchange in the body. Why the other choices are incorrect: A: Alveoli do play a role in removing carbon dioxide, but their primary function is the exchange of oxygen and carbon dioxide. C: While alveoli do transport oxygen to the bloodstream, they also exchange carbon dioxide, making this choice incomplete. D: Alveoli do not filter blood; their main function is gas exchange in the lungs.

Correct Answer: B

Rationale: The correct answer is B: Mouth. Digestion begins in the mouth where food is mechanically broken down by chewing and chemically broken down by enzymes in saliva. This initial process prepares food for further digestion in the stomach and small intestine. The stomach (A) primarily functions to further break down food through acid and enzymes. The small intestine (C) is where the majority of nutrients are absorbed, not where digestion begins. The esophagus (D) is responsible for transporting food from the mouth to the stomach, but it does not participate in the actual digestion process.

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: B

Rationale: The correct answer is B: Adrenal cortex. During stress, the adrenal cortex secretes cortisol and aldosterone, which help the body respond to stress. The parathyroid gland (A) regulates calcium levels, not stress hormones. The posterior pituitary gland (C) releases hormones like oxytocin and vasopressin, not stress hormones. The hypothalamus (D) plays a role in regulating the stress response by signaling the adrenal cortex to release stress hormones.