ImmunologyImmunologyPhagocytes Killer 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 = fluidImmunity

Lymph is filtered before returning to blood

Lymph Tissues & Organs Lymph Nodes

Clean the lymph & alert the immune system to pathogens

TonsilsGuard against ingested or

inhaled pathogens

ThymusProduces T-cells

Spleen (largest Lymph Organ)Monitors blood for foreign objectsRecycles 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 – 1st Line of Defense

Physical barrier = prevents entry of pathogens

Must beunbroken tobe effective

Acidic, oily, sweat glands–inhibitsbacterial growth

Non-Specific Body Defense

MUCUS MEMBRANESRespiratory,

Digestive,Urinary,Reproduction tracts

F(x):To trap debris

& pathogens

Non-Specific Body Defense

HAIRSNasal passageTraps debris &

pathogens CILIA

Upper Respiratory Tract

Traps debris & pathogens

Non-Specific Body Defense CELLULAR DEFENSE

Activated when other defenses are breached

Two Types:PhagocytesLeukocytes

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.

SwellingHeat

↑All four of these – due to fluid build-up

↓RednessPain

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 DEFENSEInterferons (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 antibodiesEpitope = region of antigen recognized

by a specific antibody

Stimulates formationof antibodies

Antibodies Molecules that react with or bind to

antigensMark antigens for destruction by

macrophages

Form due to the exposureto 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 chainsConstant & Variable regionsAntigen-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-cellsDirectly 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 ofcausing disease

Inactivated agents: Pieces or a whole organism that has

been chemically inactivatedCan’t reproduce but retains antigenicity

Immunity 3 Types:

ActivePassiveCell 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”)