HESI A2 Anatomy and Physiology 2023

Correct Answer: A

Rationale: Insulin is the correct answer because it is secreted by the pancreas in response to high blood glucose levels. Insulin helps to lower blood glucose levels by promoting the uptake of glucose into cells for energy storage. Glucagon, on the other hand, is secreted by the pancreas to increase blood glucose levels. Somatostatin regulates the release of insulin and glucagon but does not directly lower blood glucose levels. Cortisol is a stress hormone secreted by the adrenal glands and does not play a direct role in lowering blood glucose levels.

Correct Answer: C

Rationale: The correct answer is C: Pituitary gland. The pituitary gland is known as the 'master gland' because it controls the functions of other endocrine glands in the body by secreting various hormones that regulate growth, metabolism, reproduction, and stress response. It is located at the base of the brain and is divided into anterior and posterior lobes, each with distinct functions. The other choices are incorrect because the thyroid gland regulates metabolism (A), the adrenal gland produces hormones involved in stress response (B), and the pineal gland regulates sleep-wake cycles and melatonin production (D), but none of them have the overarching control over other glands like the pituitary gland does.

Correct Answer: A

Rationale: The correct answer is A: Left ventricle. The left ventricle is the largest and strongest chamber of the heart because it is responsible for pumping oxygen-rich blood to the entire body. It has thicker muscle walls compared to other chambers to generate enough force to push blood through the body's systemic circulation. The left atrium receives oxygenated blood from the lungs, but it does not pump blood out of the heart. The right ventricle pumps blood to the lungs for oxygenation and is not as strong as the left ventricle. The right atrium receives deoxygenated blood from the body and sends it to the right ventricle. Therefore, the left ventricle is the correct answer due to its crucial role in systemic circulation and its muscular structure.

Correct Answer: B

Rationale: The correct answer is B: White blood cells. White blood cells, also known as leukocytes, are primarily responsible for fighting infections by detecting and destroying pathogens. Red blood cells (A) carry oxygen, platelets (C) aid in blood clotting, and plasma (D) is the liquid component of blood carrying nutrients and waste. White blood cells play a crucial role in the immune system's defense against infections, making them the correct choice.

Correct Answer: B

Rationale: The correct answer is B: Vitamin K. Vitamin K is essential for blood clotting as it helps in the production of certain proteins necessary for the process. Vitamin C (choice A) is important for the immune system and collagen synthesis, not blood clotting. Vitamin A (choice C) plays a role in vision and skin health. Vitamin D (choice D) is mainly involved in calcium absorption and bone health, not blood clotting. Therefore, the correct choice is Vitamin K as it directly supports the clotting process by aiding in protein production.