HESI A2 Anatomy and Physiology 2023

Correct Answer: A

Rationale: The pituitary gland regulates metabolism by producing and secreting hormones that control various bodily functions. It plays a key role in growth, reproduction, and overall hormone balance. This is supported by its location in the brain, connected to the hypothalamus which controls hormone production. Other choices are incorrect: Bile is produced in the liver, blood filtration is mainly done by the kidneys, and muscle movement is controlled by the nervous system.

Correct Answer: C

Rationale: The correct answer is C: Retina. The retina contains specialized cells called cones that are responsible for color vision. Cones are sensitive to different wavelengths of light, allowing us to perceive colors. The cornea (A) focuses light onto the retina, the iris (B) controls the amount of light entering the eye, and the lens (D) helps to focus light onto the retina, but they do not directly contribute to color vision.

Correct Answer: A

Rationale: The correct answer is A: Nucleus. The genetic material, DNA, is located within the nucleus of a cell. This is where the DNA is stored and protected. The nucleus also houses the nucleolus, which is responsible for producing ribosomes. Mitochondria (B) is responsible for energy production, not genetic material storage. Ribosomes (C) are involved in protein synthesis, not DNA storage. Golgi apparatus (D) is responsible for packaging and processing proteins, not housing genetic material.

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: 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.