6External defense Skin produces Sweat which contains lysozymes Oil – traps bacteria / fungiMucus membranes of digestive and respiratory tract produceMucus to trap foreign particlesCilia sweep the mucus to be cleared from body
7Non-specific internal defense WHITE blood cellsMonocytes and Neutrophilsare able to cross capillary wallsuse PHAGOCYTOSIS to engulf foreign invadersNatural Killer cellsRespond to chemical message from Neutrophils; sensing molecular changes in cells causes the release of cytotoxic proteins into “foreign cell”.Monocytes differentiate into macrophages
8Non-specific internal defense Inflammatory ResponseHistamines make capillary walls “leaky”RBC, WBC, platelets and fluid cross capillary walls swelling, redness and warmth in the injured area PUS formation – tissue debris, microbes and WBC (dead and alive)
9Non-specific internal defense FEVER – triggered if pathogen is in bloodstream or infection is now systemic rather than localized.102 – 1030 F is beneficial high temp in fighting viral infections and triggers release of interferon.Interferon literally interferes with viral replication.
10Specific Internal Response aka IMMUNE RESPONSEUse LymphocytesB-Cells = humoralT-Cells = cell mediatedThymus, lymph nodes and spleen house these cells until called into action by interleukins and cytokines.
11White Blood Cells (White Blood Cells) Leukocytes lymphocytes T cells B CellsNK CellsOther Types ofWBCEosinophilsMacrophagesWhite Blood Cells
12B cellsB Memory Cells- These are the same as B plasma cells, except they remain inactive until the secondary immune responseSecondary immune response is considered anytime the body encounters a pathogen after the first time. Quicker response time.Primary response is the first time the body encounters a specific pathogen, Lag period before B cells respond.B Plasma Cells- when the B cell produces the antibody for a specific antigen, it begins to clone itself into B plasma cells, that produce more of that particular binding antibody.These cells release immunoglobulin, or antibodies.B plasma cells have a 5 to 7 day life-span; all its protein synthesis energy is going into the production of Antibodies, not self preservation.
13T cellsKiller T cells - They find specifically coded infected cells, and then destroy them with cytotoxins. They may be directed by Helper T cellsHelper T cells - secrete lymphokines that direct B cells into producing antibodies and also direct the Killer T cells as to which cell they get to eliminate.T cellsHelper T cell (Th)Memory T cellHelper T cellKiller T cellSuppressor T cellKiller T cell (Tk)Memory T cells - derived from Helper T cells, have the same properties as their parent cell, and circulates until the body encounters the pathogen its parent cells were designer for.Suppressor T cells - in charge of slowing and stopping the immune response after the foreign substance is destroyed.
14Antibodies & AntigensAntigens= a fragment of a protein or peptide from the pathogen, taken to the surface of the infected cell and bound in an MHC (major histocompatibility complex) molecule.The class 1 MHC complex molecule and the foreign peptide form the antigen, which can be read by the receptors on Killer T cells.Antibodies are produced by B cells, when stimulated by lymphokines from helper T cells. The antibody attaches to the antigen, completing the signal, coding the infected cells for destruction.Antibodies are constructed of DNA fragments, making them so unique and almost innumerable.AntigenCellClass 1 MHC moleculePathogen
15Antibodies – proteins created by B-cells that “lock” down foreign antigens Antibodies are shaped to match antigen binding sites called epitopes.Epitopes are the accessible portion of the antigen – a single bacterial surface protein can have several different epitopes.
16B-cell receptors “Y” shaped proteins extend from cell membrane. 2 heavy chains2 light chains that can be rearranged to match antigen.
17T-cell receptors a - chain b – chain 2 parallel protein chainsa - chainb – chainThese chains form the recognition site for each different antigen.
18How antigen recognition by Lymphocytes works MHC – major histocompatibility complexChemical signaling proteinsClass I MHC – found on ALL cellsto tell self from non-selfClass II MHC – found on macrophages & B-cellsdisplay antigens to Helper T-cellsAPC – antigen presenting complexChemical signaling displays antigen
19Cell mediated immunity Cell mediated =T-CellHelper T-Cells respond to chemical signals presented by macrophage.Helper T-Cells stimulate cytokines and interleukin which triggers production of B-cells and cytotoxic T-cells.Helper T cells function in both Humoral & CellMediated immunity.
20Cell mediated immunity Infected cellT-CellPerforinsT-cells attack invaders directlyPerforins released by cytoxic T-Cells create pores in infected cell resulting in ion/water inflow cell lysisEffective against intracellular parasites
21T-cells interaction with antigen presenting cells In both interactions the MHC receptor allows a T-cell to bind which starts defense response.In (a) an infected body cell alerts cytotoxic cells to destroy infected cell (short term).In (b) a macrophage displays antigen which triggers immune response (long term).
22ACTIVE – direct exposure that creates immune response. What is immunity?The ability to resist a pathogenTwo forms of immunity;ACTIVE – direct exposure that creates immune response.PASSIVE – induced exposure through vaccination.
23Immunity involves producing a primary immune response Step one – virus or bacteria infects body cellStep two – macrophage recognizes foreign antigen of pathogen and engulfs it presenting antigen to alert SPECIFIC DEFENSE SYSTEM
24Development of primary immune response - continued Step three – macrophage activates Helper T-cellsHelper T-cells set up the two prong attack of the immune response
25Development of primary immune response - continued Step four –Helper T- cells activate both plasma B-cells and Cytotoxic T-cellsStep five - B-cells form plasma cells which make antibodies to match foreign antigens of pathogenantibodies
26Development of primary immune response - continued Step five part 2- memory B-cells are created to always remember foreign antigen.Step six –Antibodies madeby plasma B-cells find & attach to pathogens antigens
27Development of primary immune response - continued Step seven - Antibodies mark pathogens for destruction.Step eight - Cytotoxic T-cells locate and destroy infected cell by making a hole in the cell membrane.
28Immune Response 2-prong attack triggered when Helper T-cells are alerted 5b. Creation of Memory B-cell
29Immunological MemoryThe reason why vaccines make sense, and we eventually build a tolerance to certain diseases…Vaccination is an introduction of a dormant or dead pathogen, which allows our body to do its primary immune response without the risk of actual sickness.It’s because after every encounter with a pathogen, both the T cells and the B cells differentiate into an inactive form of their parent cell. They remain inactive until the second immune response for that specific pathogen.
30How do vaccines work?Vaccine contains a dead or weakened pathogen or protein from pathogen.Most vaccines are only effective against infections before you get them.Vaccines can wear off overtime booster shots revive immunity.
31Immunological MemoryHeightened secondary response is due to long lived memory cells as a result of first exposure to antigen A.
32Immune Response 2-prong attack triggered when Helper T-cells are alerted