ATI TEAS Science Test

Correct Answer: A

Rationale: The correct answer is A: Glial cells. Glial cells are responsible for producing the myelin sheaths that surround and insulate nerve cells in the central and peripheral nervous systems. Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system are types of glial cells that form the myelin sheaths. Choice B, dendrites, are not involved in forming myelin sheaths; they are extensions of neurons that receive signals. Choice C, melanocytes, are cells responsible for producing melanin, not myelin. Choice D, squamous cells, are flat epithelial cells found in various tissues but are not involved in myelin sheath formation.

Correct Answer: C

Rationale: In acute appendicitis, nonpregnant patients with normal anatomy commonly experience pain in the right lower quadrant of the abdomen. The pain usually starts around the umbilicus or epigastric area and then migrates to the right lower quadrant as inflammation progresses in the appendix. This classic migration of pain is known as McBurney's point tenderness and is a key clinical feature in diagnosing appendicitis.

Correct Answer: A

Rationale: The correct answer is the Tricuspid valve. This valve is located between the right atrium and the right ventricle in the heart. Its primary function is to facilitate the flow of blood from the right atrium into the right ventricle and to prevent the backflow of blood. The Pulmonic valve (choice B) is situated between the right ventricle and the pulmonary artery, not between the right atrium and ventricle, making it incorrect. The Mitral valve (choice C) is found between the left atrium and the left ventricle, not the right side, so it is incorrect. The Aortic valve (choice D) is positioned between the left ventricle and the aorta, not involved in the right atrium and ventricle connection, hence it is also incorrect.

Correct Answer: D

Rationale: Homeostasis is defined as the tendency of the body to maintain a stable internal environment despite external changes. This process involves regulating various physiological parameters such as body temperature, blood pressure, and glucose levels to ensure optimal functioning and health. Option A is incorrect as it specifically refers to body weight regulation, which is not the sole focus of homeostasis. Option B is incorrect as it describes maintaining a constant temperature in a room, rather than the internal environment of the body. Option C is incorrect as it only addresses the prevention of hunger pains through food ingestion, which is not the overarching concept of homeostasis.

Correct Answer: A

Rationale: This mechanism is an example of negative feedback. Negative feedback systems work to counteract changes in the body and maintain a stable internal environment (homeostasis). In this case, the release of insulin in response to high glucose levels is followed by a reduction in insulin release when glucose levels drop. This response helps regulate glucose levels and return them to a normal range, demonstrating the characteristic of negative feedback where the body's response opposes the initial stimulus to maintain equilibrium. Positive feedback would amplify the initial change rather than counteract it, so it is not the correct choice. Stress response and parasympathetic regulation are not directly involved in this glucose regulation process, making them incorrect choices.