HESI A2 Anatomy and Physiology Quizlet

Correct Answer: A

Rationale: The correct answer is A: Epithelial tissue. Epithelial tissue is characterized by cells tightly packed together, lining body surfaces or cavities. In this case, the cells are found on the internal surface of the stomach, which aligns with the location of epithelial tissue in the body. The absence of extracellular matrix, tall and thin cells, and lack of blood vessels all point towards epithelial tissue, which functions in protection, absorption, and secretion. Summary: B: Connective tissue would have extracellular matrix and blood vessels. C: Muscle tissue would have muscle fibers and blood vessels. D: Cartilage tissue would have a gel-like matrix and chondrocytes.

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: A

Rationale: The correct answer is A: Melatonin. Melatonin is a hormone produced by the pineal gland that plays a key role in regulating the sleep-wake cycle. It helps control the body's internal clock and signals the brain when it's time to sleep. Melatonin levels typically rise in the evening, promoting sleep, and decrease in the morning, promoting wakefulness. Summary of incorrect choices: B: Insulin - Insulin is a hormone that regulates blood sugar levels, not the sleep-wake cycle. C: Cortisol - Cortisol is a stress hormone that helps regulate metabolism and immune response, but it does not directly control the sleep-wake cycle. D: Thyroxine - Thyroxine is a hormone produced by the thyroid gland that regulates metabolism, growth, and development, but it is not directly involved in the sleep-wake cycle regulation.

Correct Answer: B

Rationale: The correct answer is B: To fight infection. White blood cells are part of the immune system and play a crucial role in defending the body against infections by attacking and destroying pathogens such as bacteria, viruses, and other foreign invaders. They are key players in the immune response. A: White blood cells do not carry oxygen to the cells. That is the role of red blood cells. C: White blood cells do not transport nutrients. Nutrients are transported by the bloodstream and absorbed by various organs. D: White blood cells are not responsible for clotting blood. Platelets are primarily responsible for blood clotting.

Correct Answer: C

Rationale: The correct answer is C: Medulla oblongata. The medulla oblongata is located in the brainstem and is responsible for controlling vital functions such as breathing, heart rate, and blood pressure. It contains important centers that regulate these involuntary actions, making it the correct choice. The cerebrum (A) is responsible for higher brain functions such as thinking and voluntary movement. The cerebellum (B) is involved in coordination and balance. The hypothalamus (D) regulates body temperature, hunger, and thirst, but does not directly control breathing and heart rate.