PATHOLOGY

Detailed explanation-1: -White blood cells, also called leukocytes (LOO-kuh-sytes), play an important role in the immune system. Some types of white blood cells, called phagocytes (FAH-guh-sytes), chew up invading organisms. Others, called lymphocytes (LIM-fuh-sytes), help the body remember the invaders and destroy them.

Detailed explanation-2: -phagocytes (say: FAH-guh-sytes), which chew up invading germs. lymphocytes (say: LIM-fuh-sytes), which allow the body to remember and recognize previous invaders.

Detailed explanation-3: -T lymphocytes They use chemical messengers to activate other immune system cells in order to start the adaptive immune system (T helper cells). They detect cells infected by viruses or tumorous cells and destroy them (cytotoxic T cells). Some T helper cells become memory T cells after the infection has been defeated.

Detailed explanation-4: -B lymphocytes are the cells of the immune system that make antibodies to invading pathogens like viruses. They form memory cells that remember the same pathogen for faster antibody production in future infections.

Detailed explanation-5: -Some white blood cells-B cells (B lymphocytes)-can recognize invaders directly. But others-T cells (T lymphocytes)-need help from cells called antigen-presenting cells: Antigen-presenting cells ingest an invader and break it into fragments.