HESI A2 Anatomy and Physiology 2023

Correct Answer: C

Rationale: The correct answer is C: Medulla oblongata. The medulla oblongata is located in the brainstem and is responsible for regulating essential functions such as heart rate and breathing. It contains vital centers that control autonomic functions, including the cardiovascular and respiratory systems. The medulla receives inputs from various sensory receptors and sends signals to the heart and lungs to maintain homeostasis. The other choices are incorrect because: A: Cerebrum is primarily responsible for higher brain functions such as thinking and voluntary movements. B: Cerebellum is involved in coordination and balance, not in regulating heart rate and breathing. D: Hypothalamus plays a role in regulating body temperature, hunger, and thirst, but not specifically in controlling heart rate and breathing.

Correct Answer: B

Rationale: The gallbladder's function is to store and concentrate bile produced by the liver. When food is ingested, the gallbladder releases bile into the small intestine to aid in the digestion and absorption of fats. Choice A is incorrect because the liver produces bile. Choice C is incorrect as the liver, not the gallbladder, is responsible for detoxifying harmful substances. Choice D is also incorrect as blood sugar regulation is mainly controlled by the pancreas and hormones like insulin and glucagon.

Correct Answer: C

Rationale: The correct answer is C: Cortisol. Cortisol is a hormone released by the adrenal glands in response to stress. It helps regulate metabolism, immune response, and blood pressure during stressful situations. Insulin (A) is involved in regulating blood sugar levels, not the stress response. Adrenaline (B) is also known as epinephrine and is involved in the fight-or-flight response, which is part of the stress response. Melatonin (D) is a hormone that regulates sleep-wake cycles and is not directly related to the stress response.

Correct Answer: B

Rationale: The correct answer is B: Pinna. The pinna, also known as the auricle, is the most visible part of the ear located on the outside of the head. It helps collect sound waves and directs them into the ear canal. The other choices are incorrect because: A: Cochlea is a spiral-shaped organ in the inner ear responsible for hearing. C: Ear canal is the tube that connects the outer ear to the eardrum. D: Organ of Corti is a structure in the cochlea that contains sensory cells responsible for hearing.

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.