Anatomy HESI A2 Practice Test

Correct Answer: D

Rationale: The correct answer is D because the liver is responsible for producing enzymes essential for metabolism. Enzymes are biological catalysts that facilitate chemical reactions involved in breaking down nutrients and creating energy. Storing glucose (A) is mainly done by the liver and muscles, secreting bile (B) is the primary function of the gallbladder, and detoxifying harmful substances (C) is also a crucial role of the liver but not directly related to metabolism.

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: Energy production. Mitochondria are known as the powerhouse of the cell due to their role in producing energy in the form of ATP through cellular respiration. This process involves the breakdown of glucose to generate ATP, which is the main energy currency of the cell. Mitochondria have their own DNA and ribosomes, allowing them to produce some of their proteins, but they are not primarily responsible for protein synthesis (Choice A). Breaking down waste (Choice C) is mainly carried out by lysosomes. Cell division (Choice D) involves processes such as DNA replication and mitosis, which are not directly linked to the function of mitochondria.

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.