Anatomy HESI A2 Practice Test

Correct Answer: A

Rationale: The primary function of the hypothalamus is to regulate body balance and thermoregulation. It maintains homeostasis by controlling various physiological processes such as body temperature, blood pressure, and electrolyte balance. It also plays a role in regulating hormonal functions through the pituitary gland. Choices B, C, and D are incorrect because hunger, thirst, sleep, circadian rhythms, and voluntary movements are primarily controlled by other brain regions such as the amygdala, pineal gland, and motor cortex, respectively.

Correct Answer: C

Rationale: The primary function of hemoglobin in red blood cells is to carry oxygen. Hemoglobin binds to oxygen in the lungs and releases it to tissues throughout the body. This process is essential for cellular respiration. Choice A is incorrect because hemoglobin does not transport nutrients. Choice B is incorrect because the function of fighting infections is carried out by the immune system, not hemoglobin. Choice D is incorrect because hemoglobin does not produce energy; it facilitates the transport of oxygen which is necessary for energy production in cells.

Correct Answer: B

Rationale: The correct answer is B: Thymus. The thymus is not a principal organ of the nervous system; it is part of the immune system. The brain (A), ganglia (C), and spinal cord (D) are all essential components of the nervous system. The brain is the main control center, ganglia are clusters of nerve cell bodies outside the central nervous system, and the spinal cord is a major pathway for transmitting nerve signals. Therefore, the thymus stands out as the only choice that is not directly related to the nervous system, making it the correct answer in this context.

Correct Answer: B

Rationale: White blood cells' main function is to fight infections. They are part of the immune system, detecting and destroying pathogens like bacteria and viruses. They do not carry oxygen (A), nutrients (C), or remove waste products (D). White blood cells play a crucial role in protecting the body from harmful invaders, making choice B the correct answer.

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.