HESI A2 Anatomy and Physiology Quizlet

Correct Answer: A

Rationale: The main function of the circulatory system is to transport oxygen and nutrients to all cells in the body. This is achieved through the blood vessels and the pumping action of the heart. Oxygen is necessary for cellular respiration, while nutrients are essential for cell growth and metabolism. Without these, cells cannot function properly, leading to organ failure and ultimately, death. Options B, C, and D are incorrect because although the circulatory system indirectly helps remove waste products, regulate body temperature, and protect organs, these are not its primary functions.

Correct Answer: A

Rationale: The correct answer is A, to break down food and absorb nutrients. The digestive system is responsible for the mechanical and chemical breakdown of food into smaller molecules that can be absorbed by the body. This process allows the body to obtain essential nutrients for energy, growth, and repair. Choices B, C, and D are incorrect because regulating body temperature is the function of the thermoregulatory system, transporting nutrients is mainly done by the circulatory system, and hormone production is primarily carried out by the endocrine system, not the digestive system.

Correct Answer: B

Rationale: The correct answer is B: Lens. The lens is responsible for focusing light onto the retina by adjusting its shape to bend the light rays. The cornea (A) primarily helps in refracting light, while the pupil (C) and iris (D) are involved in regulating the amount of light entering the eye, not in focusing light onto the retina. Therefore, the lens is the correct choice as it plays a crucial role in the process of focusing light onto the retina.

Correct Answer: A

Rationale: The correct answer is A: Hemoglobin. Hemoglobin is a protein in red blood cells that binds to oxygen in the lungs and carries it to the body's tissues. Plasma is the liquid component of blood and does not directly carry oxygen. Platelets are responsible for blood clotting, not oxygen transport. Red blood cells contain hemoglobin and are the primary carriers of oxygen, making them indirectly responsible for carrying oxygen. However, the specific structure responsible for carrying oxygen is hemoglobin within red blood cells.

Correct Answer: B

Rationale: The correct answer is B: Pituitary gland. The pituitary gland is known as the 'master gland' because it controls the functions of other endocrine glands in the body. It secretes hormones that regulate various bodily functions, such as growth, metabolism, and reproduction. Other choices are incorrect because the thyroid gland mainly regulates metabolism, the adrenal gland is responsible for stress response and metabolism, and the pineal gland produces melatonin to regulate sleep-wake cycles. The pituitary gland stands out as the 'master gland' due to its control over other gland functions.