A decrease in the amount of white blood cells is called

A. defense and hemostasis: Hemostasis refers to blood clotting, which is a function of platelets and liver-produced proteins, not lymph nodes.

B. defense and diapedesis: Diapedesis is the process of white blood cells moving through vessel walls, not a function of the node itself.

C. defense and hematopoiesis: Lymph nodes provide defense by filtering pathogens and housing immune cells. They also perform a limited form of hematopoiesis (the final stages of lymphocyte maturation).

D. hematopoiesis and hemostasis: Hematopoiesis occurs mainly in bone marrow, and lymph nodes contribute only to lymphocyte proliferation. Hemostasis (blood clotting) is unrelated to lymph nodes.

A. Buffering: Chemical buffers in the blood (like the bicarbonate system) provide the first line of defense against pH changes.

B. Respirations: The lungs help regulate pH by exhaling or retaining carbon dioxide (CO2), which is acidic.

C. Urine secretion: The kidneys maintain long-term balance by excreting hydrogen ions (H+) and reabsorbing bicarbonate.

D. All of the above: The body requires the integrated action of chemical buffers, the respiratory system, and the urinary system to maintain a stable pH.