Chapter 12 Immunity and Body Defenses What is the difference between: Active and Passive Immunity? What is Specific/Non-Specific Defenses? What is the Immune Response? What is the Inflammatory Response?

Immune System A “Functional System” Not a traditional organ system Fight Pathogens (harmful, disease-causing microorganisms) Uses molecules and immune cells (lymphocytes and monocytes) Protects from most bacteria and viruses Protection for transplant organs/grafts

Organs of the Immune System

Immunity Using cell attack, or chemicals and antibody molecules to resist disease Resistance of an organism to diseases or any particular infection Involves both specific and non-specific components

Specific or Non-Specific Defenses

Non-Specific Body Defenses Responds immediately to protect the body from all foreign substances Provided by intact skin and mucous membranes, and cellular proteins Don’t Forget!!! Surface Membrane Barriers: first line of defense for skin and body membranes

Skin and Mucous Membranes —Secretions and Sebum are acidic to prevent bacterial growth —Keartin provides resistance against invaders —Mucus, Nasal Hairs and Cilia will trap debris —Gastric juice, Vaginal Acid Mantle, Tears and Saliva Inhibit growth

Other Non-Specific Defenses Cell and Chemical Defenders Provide defense against pathogens Phagocytesengulf and destroy pathogens Natural Killer Cellsdirect attack of virus or cancer cells

Antimicrobial Chemicals Interferonsreleased by infected cells to mobilize immune system Complement(plasma proteins) intensifies the inflammatory response Urinecleanses the lower urinary tract

Fever High body temperatures inhibit bacterial growth Enahances body repair Fosters the inflammatory and Immune responses

Inflammatory Response Triggered when body tissues are injured Signs and Symptoms: Redness, Heat, Swelling and Pain Inflammatory Responsea form of non-specific body defense --Disposes of dead cells and tissues --Promotes tissue repairs --Prevents spread of agent to adjacent tissues --Affected area releases chemicals to attract phagocytes

Inflammatory Response

Specific Body Defenses Commonly called the immune system Defends against a particular foreign substance Antigenforeign substance to the body a substance capable of prompting the immune response --Normally not part of our own body --The strongest antigens are in protein form

Antigens and Antibodies

Immune Response

Immune Response Immune Response is the immune system’s response to a threat: Increases the Inflammatory response Protects against a specific invader Primes the body for future attacks Antigens are foreign molecules recognized as invaders Provides Antibodies

Immune System

Specific Defense Action Antibodies—unique proteins that protect against future attack Humoral ImmunityProvided by antibodies present in the body’s fluids Cellular (Cell-Mediated) ImmunityLymphocytes defend the body acting on targets

Cells of the Immune System Lymphocytes and Macrophages: B Lymphocytes and T Lymphocytes (Helpers!) Phagocytic Macrophages fight invaders B CellsProduce antibodies and oversee humoral immunity T Cells Non-Antibody producing cells

B and T Cells B and T Cells generate from hemocytoblasts in red marrow T Cells originate from the Thymus Gland T Cells continuously circulate through the body B Cells develop immunocompetence in the bone marrow Once mature—B and T Cells migrate to the Spleen and Lymph Nodes

B Cell Response

T Cell Response

Macrophages Distributed throughout lymphoid organs and connective tissues Arise from monocutes in bone marrow Engulf foreign particles and present antigens to T cells Produce Monokines—Proteins important in the immune response Remain fixed and antigens come to them

Active Immunity Active Immunity—B Cells encounter antigens and produce antibodies against them Naturally acquired during infections Artificially acquired (Vaccines) Vaccines a preparation of killed microorganisms, living attenuated organisms, or living fully virulent organisms that is administered to produce or artificially increase immunity to a particular disease

Why Vaccinate? Vaccine Benefits: not exposed to signs or symptoms of a disease stimulate antibody production

Passive Immunity Antibodies are obtained from serum of a donor  Cells are not challenged by the antigen Examples: Fetus gets immunity from the mother Gamma Globulin is injected for a snake bit