HESI A2 Anatomy and Physiology Practice Test

Correct Answer: C

Rationale: The correct answer is C: Alveoli. Alveoli are tiny air sacs in the lungs where gas exchange occurs. Oxygen is taken in from the air into the bloodstream, and carbon dioxide is released from the bloodstream into the air in the alveoli. Trachea (A) is the windpipe that carries air to the lungs, bronchioles (B) are smaller airways that branch off from the bronchi, and larynx (D) is the voice box. These structures are important for breathing but not directly involved in gas exchange. Hence, the alveoli are the correct choice for gas exchange in the respiratory system.

Correct Answer: D

Rationale: The correct answer is D: T4. The thyroid gland primarily secretes thyroxine (T4), which plays a key role in regulating metabolism and energy production in the body. Oxytocin (A) is a hormone produced by the pituitary gland, not the thyroid. TSH (B) is thyroid-stimulating hormone produced by the pituitary gland to stimulate the thyroid to produce T4. Adrenaline (C) is produced by the adrenal glands, not the thyroid. T4 is the main hormone secreted by the thyroid gland, making it the correct answer.

Correct Answer: C

Rationale: The correct answer is C: Alveoli. Alveoli are tiny air sacs in the lungs where gas exchange occurs. Oxygen is taken in from the air into the bloodstream, and carbon dioxide is released from the bloodstream into the air in the alveoli. Trachea (A) is the windpipe that carries air to the lungs, bronchioles (B) are smaller airways that branch off from the bronchi, and larynx (D) is the voice box. These structures are important for breathing but not directly involved in gas exchange. Hence, the alveoli are the correct choice for gas exchange in the respiratory system.

Correct Answer: C

Rationale: The gall bladder belongs to the digestive system. It stores bile produced by the liver, which aids in the digestion of fats in the small intestine. The endocrine system (A) regulates hormones, the urinary system (B) filters and eliminates waste, and the nervous system (D) controls body functions through nerve signals. The gall bladder's primary function of storing bile for digestion aligns with its classification within the digestive system.

Correct Answer: A

Rationale: The correct answer is A: Hormones. Hormones are chemical messengers that are produced by endocrine glands and control growth, differentiation, and metabolism of specific target cells. They are released into the bloodstream and travel to target cells to elicit a response. Neurons (B) are nerve cells that transmit electrical signals, not chemical messengers. Glands (C) are structures that produce and secrete substances, including hormones, but they are not the chemical messengers themselves. Second messengers (D) are molecules involved in signal transduction pathways within cells, not the primary chemical messengers that control growth, differentiation, and metabolism.