Immunology PhagocytesKiller T-cells Macrophages Natural Killer Cells

Immune System Group of cells in the body that recognize foreign substances F(x) = to neutralize or destroy all things “non-self” (pathogens or invaders)

What is a Pathogen? Any toxin, living organism, or other agent that can cause disease.

Immune Cells Immune cells circulate throughout the body in the blood system and the lymphatic system

Lymphatic System A network of vessels that penetrate nearly every tissue of the body, and a collection of tissues & organs that produce immune cells F(x):  Fluid recovery from tissues Lymph = fluid  Immunity Lymph is filtered before returning to blood

Lymph Tissues & Organs Lymph Nodes  Clean the lymph & alert the immune system to pathogens Tonsils  Guard against ingested or inhaled pathogens Thymus  Produces T-cells Spleen (largest Lymph Organ)  Monitors blood for foreign objects  Recycles old RBCs TONSIL

Body Defense - Two Types 1. Non-Specific 2. Specific

Non-Specific Body Defense Innate or inborn, not affected by prior exposures NOT specific for any invader Operates constantly

Non-Specific Body Defense SKIN – 1 st Line of Defense  Physical barrier = prevents entry of pathogens  Must be unbroken to be effective  Acidic, oily, sweat glands– inhibits bacterial growth

Non-Specific Body Defense MUCUS MEMBRANES  Respiratory, Digestive, Urinary, Reproduction tracts  F(x): To trap debris & pathogens

Non-Specific Body Defense HAIRS  Nasal passage  Traps debris & pathogens CILIA  Upper Respiratory Tract  Traps debris & pathogens

Non-Specific Body Defense CELLULAR DEFENSE  Activated when other defenses are breached  Two Types: Phagocytes Leukocytes Phagocyte eating dying cells.

Phagocytes Cell’s that recognize “non-self” items F(x): engulf or “eat” foreign debris Reside in lymph organs Travel to the site of infection, via the blood stream  Macrophage – a type of phagocyte

Leukocytes (Natural Killer Cells) a.k.a. NK Cells WBCs police the blood & lymph F(x):  Bind to membrane of the invader, release chemicals, cause infected cell to lyse

Non-Specific Body Defense CELLULAR (TISSUE) DEFENSE  Inflammatory Response  Fever

Inflammation Local defensive response to tissue injury of any kind Response is directly at site of injury Helps to prevent spread of the damaging agent

Inflammation The 4 Signs of Inflammation – S.H.A.R.P.  Swelling  Heat ↑  All four of these – due to fluid build-up ↓  Redness  Pain

Fever Abnormal elevation in body temp.  Response to infection Stimulates phagocytes to go to work Heat kills many pathogens Increases the rate of enzymatic rxns

Non-Specific Body Defense CHEMICAL DEFENSE  Interferons (antiviral proteins)

Interferons Secreted by virus-infected cell Stimulates non-infected cells to make proteins that block viral protein synthesis Slows infection to allow specific defenses to begin working Activates macrophages to “eat” (non-self) viral invaders

Specific Body Defense Immunity = ability to ward off a specific infection or disease  Highly specific resistance to disease Process:  Particular invader recognized  Switches on immune response  Invader is remembered so that future invasions can be immediately fought

Specific Body Defense Specific Body Defense is born out of the Lymphatic System  i.e. Bone marrow  makes B-cells, which make specific antibodies

Antigens Irritant or pathogen– molecule that react with antibodies  Epitope = region of antigen recognized by a specific antibody Stimulates formation of antibodies

Antibodies Molecules that react with or bind to antigens  Mark antigens for destruction by macrophages Form due to the exposure to a specific antigen

Antibodies Made by B-cells Found in plasma, & all body secretions Once present, allows immediate immune response to pathogens

Antibodies Structure (most common)  Composed of 2 heavy chains, 2 light chains  Constant & Variable regions  Antigen-binding site Variable region Constant region

Specific Body Defense Helper T-cells  Attract other T-cells (Killer T-cells) and macrophages to an antigen Killer T-cells  Directly attack & kill pathogens, release chemicals to lyse cells

Specific Body Defense Suppressor T-cells  Stops immune response when antigen is successfully overcome Scanning Electron Micrograph of a T-cell

Specific & Non-specific Defenses work together to protect the body from disease-producing pathogens B-cells mature in bone tissue T-cells mature in thymus tissue

Applications of Immune Response Immunization= process that increases an organism’s rxn to antigen & therefore improves its ability to resist or overcome infection. Vaccine= living or inactivated organism used to induce specific immunity

Vaccines Attenuated agents:  Virus/bacteria that has been modified to be incapable of causing disease Inactivated agents:  Pieces or a whole organism that has been chemically inactivated  Can’t reproduce but retains antigenicity

Immunity 3 Types:  Active  Passive  Cell Mediated

Active Immunity When an individual responds to an antigen  Resulting from vaccination against or  Recovery from a natural infection Permanent Immunity

Passive Immunity Antibodies produced from another organism injected into the body Temporary protection against disease

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