HESI A2 Anatomy and Physiology 2023

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.

Correct Answer: C

Rationale: The correct answer is C: Front portion of the parietal lobe. This area is known as the primary motor cortex, responsible for planning, control, and execution of voluntary movements. It receives input from other brain regions involved in movement. Choices A, B, and D are incorrect because the top, middle portion of the parietal lobe is involved in sensory processing, the back of the head is associated with the occipital lobe responsible for vision, and around the auditory cortex is involved in processing auditory information, respectively.

Correct Answer: B

Rationale: During the fight-or-flight response, the body needs to prepare for immediate action. Adrenaline, also known as epinephrine, is the hormone released by the adrenal glands in response to stress or danger. Adrenaline triggers physiological changes such as increased heart rate, blood flow to muscles, and heightened awareness to help the body react quickly. Insulin is involved in regulating blood sugar levels, not the fight-or-flight response. Thyroxine plays a role in metabolism, while cortisol is released in response to stress but is not the primary hormone involved in the fight-or-flight response.

Correct Answer: B

Rationale: The correct answer is B: Parathyroid hormone. Parathyroid hormone is produced by the parathyroid glands and plays a crucial role in regulating calcium levels in the blood. It does so by increasing calcium absorption in the intestines, reabsorption in the kidneys, and release from bones. Insulin (choice A) regulates blood sugar, not calcium. Cortisol (choice C) is a stress hormone and does not directly affect calcium levels. Melatonin (choice D) regulates sleep-wake cycles and does not play a role in calcium regulation. Therefore, the correct choice is B as it directly influences calcium levels in the blood.

Correct Answer: C

Rationale: The correct answer is C: Thyroid gland. The thyroid gland secretes hormones that regulate metabolism and calcium levels in the body. It produces thyroxine (T4) and triiodothyronine (T3) which control the body's metabolic rate. This gland also plays a crucial role in maintaining calcium levels in the blood. The other choices, A: Pituitary gland, B: Adrenal gland, and D: Pineal gland, do not primarily regulate metabolism and calcium levels in the body. The pituitary gland controls various other hormones, the adrenal gland is responsible for stress response and hormone regulation, and the pineal gland regulates sleep-wake cycles and melatonin production.