ATI Anatomy and Physiology

Correct Answer: D

Rationale: The correct answer is Parathyroid glands. The parathyroid glands are responsible for regulating calcium levels in the blood by secreting parathyroid hormone (PTH). PTH helps increase calcium levels in the blood when they are too low. The other glands listed, such as the Hypothalamus, Thyroid, and Pituitary glands, do not directly control calcium concentration in the blood.

Correct Answer: A

Rationale: The correct answer is the Ileum. The Ileum is the final section of the small intestine where the absorption of key nutrients such as iron and bile salts occurs. The Jejunum mainly absorbs nutrients like carbohydrates and proteins, while the Duodenum primarily facilitates the absorption of minerals and vitamins. The Colon's main function is to absorb water and electrolytes, not iron and bile salts. Therefore, choices B, C, and D are incorrect.

Correct Answer: C

Rationale: Calcium plays an essential role in the clotting of blood by being involved in several steps of the coagulation process. It is necessary for the conversion of prothrombin to thrombin, which is a crucial step in forming blood clots. Sodium, magnesium, and potassium do not directly participate in the clotting cascade and are not associated with the coagulation process. Therefore, the correct answer is calcium.

Correct Answer: D

Rationale: Macrophages are a type of white blood cell that plays a crucial role in the immune system by engulfing and digesting cellular debris, foreign substances, microbes, cancer cells, and old or damaged cells. Basophils are primarily involved in allergic reactions and parasitic infections, eosinophils combat multicellular parasites and have a role in allergic reactions, and B-cells are responsible for producing antibodies. Therefore, the correct answer is macrophages as they are specialized in phagocytosis and removal of unwanted cells and microorganisms.

Correct Answer: B

Rationale: The correct function associated with the dermal layer of the skin is to provide support and structure to the skin. The dermis is the thickest layer of the skin and is responsible for maintaining the skin's integrity and firmness. Choices A, C, and D are incorrect as sensory perception, protection from UV rays, and insulation are functions associated with other layers of the skin, such as the epidermis and subcutaneous tissue.