Immune System Phagocytes Killer T-cells Macrophages Natural Killer Cells

Immune system Function = destroy & remove all “non-self” (pathogens/invaders) Often considered part of the Circulatory System 2 Types of Body defenses = 1. Non-specific 2. Specific

I. Non-Specific Body Defenses Effective against all infections First line of defense – Skin 1. Physical barrier prevents entry of pathogens (micro-organisms) 2. Must be unbroken to be effective 3. Skin is acidic, plus oil & sweat glands inhibit bacterial growth

Non-Specific Body Defenses B. Mucus Membranes 1. Location: respiratory, digestive, urinary, & reproductive tracts 2. F(x) = trap pathogens & debris

Non-Specific Body Defenses C. Hairs (nasal passages) F(x) = trap pathogens & debris Nose hairs

Non-Specific Body Defenses D. Cilia - throat (upper respiratory tract) - trap pathogens & debris

Non-Specific Body Defenses E. Cellular & Chemical defenses Activated when outer defenses are breached

1. Phagocytes a. Cells that recognize “non-self”, i.e. foreign particles or invaders Phagocyte eating dying cells

1. Phagocytes b. E.g. White Blood Cells (WBCs) such as neutrophils & macrophages c. Travel to infection site via circulatory system (bloodstream) or lymphatic system d. Can squeeze through intercellular spaces

1. Phagocytes d. Engulf (“eat”) invaders / foreign debris e. Release lysosomes to dissolve invaders / foreign debris Phagocytes & yersinia pestis

2. Natural Killer Cells (NK cells) a. WBCs – police the blood & lymph b. Bind to membrane of invader, release chemicals, lyse cell

3. Inflammatory Response a. Inflammation = heat, redness, swelling due to fluid build-up, pain b. Localized response at site of tissue damage c. Prevents spread of damaging agent

Inflammatory Response

Inflammatory Response

4. Fever a. Systemic response to infection b. Stimulates phagocytes (WBCs) to work c. Heat kills many pathogens

5. Interferon a. Secreted by virus-infected cells b. Stimulates non-infected cells to make proteins that block viral protein synthesis c. Slows infection to allow specific defenses to begin working d. Activates macrophages to “eat” (non-self) viral invaders

II Specific Body Defenses (against a specific pathogen) General Information Create Immunity = highly specific resistance to disease Particular invader recognized, switches on immune response Specific Invader is remembered so that future invasions can be immediately fought

II Specific Body Defenses B. Antigen 1. Irritant or pathogen 2. Stimulates formation of antibody

C. Antibody i.e. Bone marrow  makes B-cells, which make specific 1. Forms due to exposure to a specific antigen 2. Produced by B-cells i.e. Bone marrow  makes B-cells, which make specific antibodies 3. Binds to antigen to mark it for destruction by macrophages

C. Antibody 4. Found in plasma & all body secretions 5. Once present, allows immediate immune response to pathogens 6. (memory B cells remember pathogen, so next exposure brings rapid response)

Antigen Antibody Response Antibodies Antigens

D. Macrophages - destroy cells marked by antigen-antibody complex

E. Helper T-cells Activate other T-cells Attract Killer T cells & macrophages to an antigen

F. Killer T-cells – directly attack & kill pathogens, release cytotoxic chemicals to lyse cells

G. Suppressor T-cells - stop immune response when antigen is successfully overcome

Notice ! Non-specific and Specific Defenses work together to protect the body from disease-producing pathogens

Origins of cells B cells mature in bone tissue T cells mature in thymus tissue

Types of Immunity (3) long-lasting) 1. Active – vaccinated against or recovered from the disease (immunity permanent or long-lasting)

Types of Immunity (3) 2. Passive – antibodies produced by another organism injected into body (temporary protection against the disease)

Types of Immunity (3) 3. Cell Mediated – killer T-cells attack any cell not marked with a special protein (i.e. cells that are “non-self”)

Cell-mediated Immunity

Immune system Vaccine= living or inactivated organism used to induce specific immunity Can be made from antibodies, or cause antibodies to be made Immunization= process that increases an organism’s rxn to antigen & therefore improves its ability to resist or overcome infection