Anatomy HESI A2 Practice Test

Correct Answer: B

Rationale: The correct answer is B: Lens. The lens of the eye is responsible for focusing light onto the retina by changing its shape to adjust the focal length. The cornea (A) helps in the initial focusing of light but does not have the ability to adjust focus. The retina (C) is the layer of cells at the back of the eye where light is converted into electrical signals, not responsible for focusing light. The pupil (D) controls the amount of light entering the eye but does not focus light onto the retina.

Correct Answer: B

Rationale: The correct answer is B: Lens. The lens of the eye is responsible for focusing light onto the retina by changing its shape to adjust the focal length. The cornea (A) helps in the initial focusing of light but does not have the ability to adjust focus. The retina (C) is the layer of cells at the back of the eye where light is converted into electrical signals, not responsible for focusing light. The pupil (D) controls the amount of light entering the eye but does not focus light onto the retina.

Correct Answer: A

Rationale: The correct answer is A: Diaphragm. The diaphragm is the primary muscle responsible for breathing as it contracts and moves downward during inhalation, creating more space in the chest cavity for the lungs to expand. The intercostal muscles assist in expanding and contracting the ribcage during breathing, but they are not the primary muscle responsible. The rectus abdominis is involved in core stabilization and movement but not in the breathing process. The pectoralis major is a chest muscle that aids in arm movements but is not directly involved in the breathing mechanism. Therefore, the diaphragm is the correct answer as it plays a crucial role in the breathing process.

Correct Answer: A

Rationale: The correct answer is A: They secrete chemicals into the blood. Endocrine glands are ductless glands that secrete hormones directly into the bloodstream. This allows the hormones to travel throughout the body to target organs and tissues. Choices B, C, and D are incorrect because endocrine glands do not secrete enzymes into ducts (B), produce sweat (C), or produce saliva (D). These functions are typically associated with exocrine glands that have ducts for secretion.

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.