HESI A2 Anatomy and Physiology 2023

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.

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: 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: C

Rationale: The motor cortex is located in the front portion of the parietal lobe. This is because it is primarily responsible for planning, executing, and controlling voluntary movements of the body. The parietal lobe is known for processing sensory information, making it an ideal location for integrating sensory inputs with motor commands. Choices A, B, and D are incorrect because the motor cortex is specifically situated in the frontal lobe, not the top or back of the head or around the auditory cortex.

Correct Answer: B

Rationale: The correct answer is B: cartilage. Cartilage is the substance that makes up the pads between the vertebrae, known as intervertebral discs. Cartilage provides cushioning and support, allowing for flexibility and shock absorption in the spine. Bone (A) is a hard tissue that forms the structure of the vertebrae but does not provide the cushioning function of the discs. Tendon (C) is a fibrous tissue that connects muscle to bone and does not play a role in supporting the vertebrae. Fat (D) is a type of adipose tissue that is not found in the pads between the vertebrae.