Anatomy HESI A2 Practice Test

Correct Answer: B

Rationale: The correct answer is B: To transport oxygen. Hemoglobin is a protein in red blood cells that binds to oxygen in the lungs and carries it to tissues throughout the body. This process is essential for cellular respiration and energy production. Choice A is incorrect because fighting infections is the role of the immune system, not hemoglobin. Choice C is incorrect as hemoglobin primarily carries oxygen, not carbon dioxide. Choice D is incorrect as hemoglobin binds and releases oxygen to tissues, rather than storing it.

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: The correct answer is B: Semicircular canals. These structures in the inner ear are responsible for detecting rotational movement and maintaining balance. The semicircular canals contain fluid that moves in response to head movements, stimulating hair cells that send signals to the brain about the body's position in space. A: The cochlea is responsible for hearing, not balance. C: Ossicles are tiny bones in the middle ear that transmit sound vibrations to the cochlea. D: The Eustachian tube helps equalize pressure in the middle ear and is not directly related to balance. In summary, the semicircular canals are crucial for maintaining balance by detecting rotational movements, while the other structures mentioned are primarily involved in hearing or pressure regulation.

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.