Blood & Immunity. Notes. First line of defense. physical barriers – skin and membranes that line body cavities skin provides a protective barrier that cannot normally be penetrated by bacteria or viruses . chemical barriers – sweat, tears, saliva, mucus, stomach acid
The macrophage will extend long pseudopods and engulf the invading microbe
As pathogen is removed, number of injured cells decreases, amount of warning chemical subsides, inflammation dies down, and the wound heals
(a) At the first sign of injury, chemical signals are released by the foreign invader. Other chemicals— histamines and prostaglandins—are
released by the cells of the body.
(b) Chemical signals cause the capillaries to dilate. Blood flow increases and the
capillaries become more
phagocytic cells and
specialized white blood
(c) Phagocytes engulf and digest the invaders and cellular debris, which promotes healing of the tissues.
total body attack against pathogen (bone marrow, WBC, lymphatic system, tonsils, thymus, and spleen)!!!
Complement proteins, T cells and B cells all play an important role in fighting off bacteria
B cells – produced in the bone marrow; produce antibodies in response to the T cells; each B cell produces a single type of antibody which is displayed on its membrane; some will differentiate into super-anitbody producing plasma cell, which produce as many as 2000 antibody molecules every second
Sugar-protein complexes located on the cell membrane act as markers. T cells distinguish the markers on the body’s cells from those of invading cells.
Some of the activated proteins trigger the formation of a protective coating around the invader, which immobilizes it.
The antibodies bind to the antigens and that attracts more phagocytes, which eat the antigen.
HIV has a shape that provides access to the T cell. The T cell engulfs HIV, unlike most other viruses.