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-specificcomponents

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

Phagocytesengulf and destroy pathogens

Natural Killer Cellsdirect attack of virus or cancer cells

Antimicrobial Chemicals

Interferonsreleased by infected cells to mobilize immune system

Complement(plasma proteins) intensifies the inflammatory response

Urinecleanses the lower urinary tract

Fever

• High body temperatures inhibit bacterial growth

• Enahances body repair

• Fosters the inflammatory and Immune responses

Inflammatory ResponseTriggered when body tissues are injuredSigns and Symptoms:

Redness, Heat, Swelling and Pain

Inflammatory Responsea 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 systemDefends against a particular foreign substance

Antigenforeign 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 responseProtects against a specific invaderPrimes the body for future attacksAntigens are foreign molecules recognized as invadersProvides Antibodies

Immune System

Specific Defense Action

Antibodies—unique proteins that protect against future attack

Humoral ImmunityProvided by antibodies present in the body’s fluids

Cellular (Cell-Mediated) ImmunityLymphocytesdefend the body acting on targets

Cells of the Immune System

Lymphocytes and Macrophages:• B Lymphocytes and T Lymphocytes (Helpers!)• Phagocytic Macrophages fight invaders

B CellsProduce 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 marrowEngulf foreign particles and present antigens to T cellsProduce Monokines—Proteins important

in the immune responseRemain fixed and antigens come to them

Active Immunity

Active Immunity—B Cells encounter antigens and produce antibodies against them

Naturally acquired during infectionsArtificially 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

diseasestimulate 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