HESI A2 Anatomy and Physiology Quizlet

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 proteins necessary for the clotting process. Deficiency in Vitamin K can lead to excessive bleeding. A: Vitamin A is important for vision and immune function, not blood clotting. C: Vitamin C is important for collagen synthesis and immune function, not blood clotting. D: Vitamin D is important for calcium absorption and bone health, not blood clotting.

Correct Answer: B

Rationale: The correct answer is B: Hypothalamus. The hypothalamus plays a crucial role in regulating body temperature through its control over thermoregulation processes. It receives input from temperature receptors in the body and initiates responses to maintain a stable internal temperature. The other choices are incorrect because the cerebellum is primarily responsible for coordination and balance, the medulla oblongata controls vital functions like breathing and heart rate, and the pineal gland regulates sleep-wake cycles through the secretion of melatonin.

Correct Answer: C

Rationale: The correct answer is C: Smooth muscle. Smooth muscle tissue is found in the walls of hollow organs such as the intestines, blood vessels, and bladder. It is involuntary, non-striated, and capable of sustained contractions. Skeletal muscle (A) is attached to bones and is under voluntary control. Cardiac muscle (B) is found in the heart and has a unique branching structure. Striated muscle (D) includes both skeletal and cardiac muscle, but smooth muscle specifically lines hollow organs.

Correct Answer: C

Rationale: The correct answer is C: Pineal gland. The pineal gland secretes melatonin, a hormone responsible for regulating sleep-wake cycles. It receives signals from the retina about light levels, which helps to synchronize the body's internal clock. The hypothalamus (A) regulates various bodily functions but is not specifically responsible for sleep-wake cycles. The thalamus (B) is involved in relaying sensory information but not directly related to sleep regulation. The cerebellum (D) is primarily involved in motor control and coordination, not sleep regulation. Therefore, the pineal gland is the structure in the brain that directly regulates sleep and wakefulness.

Correct Answer: C

Rationale: The main component of the cell membrane is lipids, specifically phospholipids. They form a lipid bilayer that provides structure and acts as a barrier to regulate what enters and exits the cell. Proteins are also important in the cell membrane for various functions, but they are not the main component. Carbohydrates are found on the surface of the cell membrane for cell recognition and communication, not as the main component. Nucleic acids are not found in the cell membrane, as they are responsible for genetic information storage and protein synthesis inside the cell.