Anatomy HESI A2 Practice Test

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: Cerebrum. The cerebrum, specifically the motor cortex located in the frontal lobe, controls voluntary movement. It sends signals to the muscles via the spinal cord. The cerebellum (A) is responsible for coordination and balance, not voluntary movement. The brainstem (C) controls basic life functions like breathing and heart rate, while the medulla oblongata (D) regulates vital functions such as blood pressure and breathing, not voluntary movement. Therefore, the cerebrum is the correct choice for controlling voluntary movement.

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: A

Rationale: The primary function of the liver is to detoxify harmful substances. It metabolizes and neutralizes toxins, drugs, and other harmful compounds. It does this through various enzymatic processes. Producing bile (choice B) is an important function of the liver, but it is not the primary function. Producing insulin (choice C) is a function of the pancreas, not the liver. Storing glycogen (choice D) is a function of the liver, but it is not the primary function.