40-2 The Immune System Pg. 1036

Introduction 1. The immune system fights infection by producing cells that inactivate (DEFEAT!) foreign substances/cells.

A. Nonspecific Defenses 1. Nonspecific defenses do not discriminate.

A. Nonspecific Defenses 2. Skin is the first line of defense and most important nonspecific defense.

A. Nonspecific Defenses 3. The 2 nd line of defense is an inflammatory response which occurs in response to injury/infection.

A. Nonspecific Defenses 4. Another 2 nd line of defense is a fever when the body tries to kill pathogens/fight infection.

B. Specific Defenses 1. Immune responses attack specific substances called antigens (viruses, bacteria, etc.)

B. Specific Defenses 2. Two types of cells recognize specific antigens: – B Lymphocytes (B Cells) – T Lymphocytes (T Cells)

B. Specific Defenses 3. B cells provide immunity through body fluids; this process is called humoral immunity.

B. Specific Defenses 4. T cells provide immunity to against pathogens INSIDE the cell; this process is called cell mediated immunity.

B. Specific Defenses 5. T cells can become – Killer T cells that track down/destroy antigens – Helper T cells that make Memory T cells – Memory T cells that respond if the same antigen enters the body again.

B. Specific Defenses 6. When antigens enter the body, plasma cells release antibodies. 7. Antibodies are proteins that recognize/bind to antigens.

Think about it? Why would it be difficult to accept an organ transplant???

C. Acquired Immunity 1. Vaccinations are a form of acquired immunity where an individual receives a weakened form of the pathogen to produce immunity.

C. Acquired Immunity 2. Active immunity is the body's response to a vaccine by making antibodies. 3. Passive immunity is when antibodies are injected into the bloodstream.