Venous blood in systemic circulation is poorer in oxygen and richer in carbon dioxide.

Changes in the immune system that accompany aging include:

The process of breathing is known as pulmonary ventilation.

Tissue grafts harvested from an unrelated person are called xenografts.

Natural killers are unique phagocytic defense cells that can kill cancer cells and virus-infected body cells well before the immune system is activated.

Memory cells are descendants of an activated B or T cell.

_____ immunity – defense against antigens and pathogenic organisms in body fluids

The antibody a mother passes to her fetus is IgM.

Exchange of both oxygen and carbon dioxide through the respiratory membrane occurs by:

Air moving in and out of the lungs is called: