Quizlet HESI A2 Anatomy and Physiology

Correct Answer: B

Rationale: The correct answer is B: Lens. The lens in the eye is responsible for focusing light on the retina by changing its shape to adjust the focal point. The cornea (A) helps to initially focus light but does not have the ability to adjust focus. The retina (C) is the light-sensitive layer that receives focused light, not the structure that focuses light. The pupil (D) regulates the amount of light entering the eye but does not focus light on the retina.

Correct Answer: A

Rationale: The correct answer is A: Pineal gland. The pineal gland is located in the brain and is responsible for producing melatonin, which regulates sleep-wake cycles. Melatonin is not produced by the thyroid gland (B), pituitary gland (C), or adrenal gland (D). The thyroid gland produces hormones that regulate metabolism, the pituitary gland regulates various hormones, and the adrenal gland produces hormones like cortisol and adrenaline. Therefore, the pineal gland is the correct answer as it specifically produces melatonin.

Correct Answer: B

Rationale: Platelets play a crucial role in blood clotting. When a blood vessel is damaged, platelets adhere to the site to form a plug to stop bleeding. This process is essential for wound healing and preventing excessive blood loss. Platelets do not transport oxygen (A), fight infection (C), or transport nutrients (D). Oxygen is carried by red blood cells, immune cells fight infection, and nutrients are transported by plasma and other blood components.

Correct Answer: C

Rationale: The correct answer is C: Vitamin D. Vitamin D is essential for calcium absorption in the intestines by promoting the production of proteins that transport calcium. Without sufficient Vitamin D, the body cannot effectively absorb calcium, leading to potential bone and muscle weakness. Choice A: Vitamin A is not directly involved in calcium absorption. Choice B: Vitamin C is important for collagen synthesis and immune function but does not play a significant role in calcium absorption. Choice D: Vitamin K is primarily involved in blood clotting and bone health but does not directly affect calcium absorption.

Correct Answer: A

Rationale: The correct answer is A: To transport oxygen and nutrients. The cardiovascular system consists of the heart, blood vessels, and blood. It is responsible for circulating oxygen and nutrients to all cells in the body and removing waste products. Oxygen and nutrients are essential for cell function and energy production. Regulating body temperature is primarily the function of the respiratory system and sweat glands, not the cardiovascular system. Fighting infections is the role of the immune system, not the cardiovascular system.