Anatomy HESI A2 Practice Test

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.

Correct Answer: C

Rationale: Platelets play a crucial role in blood clotting, known as hemostasis. Step 1: When a blood vessel is damaged, platelets adhere to the site to form a temporary plug. Step 2: Platelets release chemicals that attract more platelets and help in clot formation. Step 3: This clotting process prevents excessive bleeding. Choice A is incorrect as oxygen is primarily carried by red blood cells. Choice B is incorrect as fighting infections is mainly done by white blood cells. Choice D is incorrect as nutrient transport is mainly carried out by the plasma in the blood.

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: 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: Vitamin A. Vitamin A is essential for vision as it plays a crucial role in the function of the retina and helps maintain a healthy cornea. It is also important for skin health by promoting skin cell growth and repair. Vitamin C (B) is important for immune function and collagen synthesis, not specifically for vision or skin health. Vitamin D (C) is crucial for bone health and immune function. Vitamin E (D) is an antioxidant that helps protect cells from damage, but it is not specifically essential for vision or skin health.