Biology  5/e   Raven/Johnson
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Phagocytosis: During phagocytosis a cell engulfs food particles (such as another cell or fragments of an organism) by enfolding it within extensions of its cell membrane. As a result, the food particles wind up inside the cell in a vesicle where they can be broken down by digestive enzymes. Phagocytosis allows the bulk passage of material into the cell, material that is too large to enter the cell by diffusion or through transmembrane channels.

Recombination: Recombination is the architect of the genome. Mutation is the ultimate source of new genetic material, but recombination is responsible for the reshuffling of existing genetic material that results in the genetic diversity and myriad of allele combinations that we see in species. Recombination can occur by the exchange of entire chromosomes, as occurs during meiosis and sexual reproduction, and it can occur by the exchange of parts of chromosomes (e.g., crossing-over, gene transfer) or rearrangement within a single chromosome.

Macrophage: Macrophages are one of the types of connective tissue cells. They are specialized types of white blood cells that are phagocytic. They circulate throughout the body and engulf and digest invading bacteria, foreign material, and cellular debris. They will phagocytize any cell coated with antibodies and can thus detect and remove diseased cells that are carrying antibodies.

Lymphocyte: Lymphocytes are another type of defensive specialized white blood cell. They circulate in the blood and produce antibodies in response to the presence of foreign material. The antibodies are a crucial component in the body's defense against disease.

The lymphatic system: The closed circulatory system of vertebrates is not completely closed – some of the fluid that diffuses out of the plasma as the blood passes through the capillaries is not taken back in by the capillaries. This fluid is collected by the lymphatic system, which returns it to the bloodstream near the heart. Defensive white blood cells are also found in the lymphatic system.

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