HESI A2 Anatomy and Physiology 2023

Correct Answer: B

Rationale: The correct answer is B: Skeletal muscle. Skeletal muscle is voluntary as it is under conscious control, allowing us to move our body voluntarily. Cardiac muscle (A) is involuntary and found in the heart. Smooth muscle (C) is also involuntary and found in internal organs. Striated muscle (D) is a general term that can refer to both skeletal and cardiac muscle, but not all striated muscles are voluntary. Therefore, B is the correct answer as it specifically refers to the type of muscle tissue that is under voluntary control.

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: 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: 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.

Correct Answer: B

Rationale: The correct answer is B: Skin. The skin is the largest organ in the human body by surface area, covering about 20 square feet on average. It serves as a protective barrier against external elements and plays a crucial role in regulating body temperature. The liver (A), brain (C), and heart (D) are important organs, but they are not the largest in terms of size or surface area. Therefore, the correct choice is the skin.