Specific Immunity: the body’s 3 rd line of defense

The Immune System is the Third Line of Defense Against Infection

Specific Immunity Basics… Specific Immunity- the body’s way of attacking a specific type of pathogen –Mechanisms involved do not attack everything that’s bad –These mechanisms are considered your body’s 3 rd line of defense Specific Immunity cells in your body use the “lock & key” method of identification- distinguish “self” from “not self (pathogen)”

Must meet or be primed by specific pathogen before it can protect the body

Specific Immunity Naturally Acquired A.Active- –Body generates an immune response to antigens. –Immunity may be lifelong (chickenpox or mumps) or temporary (influenza or intestinal infections). B. Passive- Antibodies pass from mother to fetus via placenta or breast feeding (colostrum). –No immune response to antigens, short lived

Specific Immunity Artificially Acquired A. Active –Antigens are introduced in vaccines (immunization). –Body generates an immune response to antigens. Immunity can be lifelong (oral polio vaccine) or temporary (tetanus toxoid) B. Passive Immunity: – Preformed antibodies (antiserum) are introduced into body by injection. Snake antivenom injection from horses or rabbits. –Immunity is short lived (half life three weeks). –Host immune system does not respond to antigens.

Specific Immunity Basics… - Antigens and Ligands are like “flags” Almost all of your body cells have Ligands, protein markers attached to their plasma membrane these are “self” marker proteins Foreign pathogens have Antigens on their surface -these are “not self” marker proteins –Auto Immune Diseases

Specific Immunity Basics Continued… Important cells involved include: Macrophages T-Lymphocytes (T-Cells) –Helper T-cells –Cytotoxic T-cells –Memory T-cells B –Lymphocytes (B-Cells) -Plasma B-cells -Memory B-cells

Specific Immunity Basics… Resistance=Immunity –Happens AFTER the first exposure to pathogen – Memory cells will launch a faster, more massive, attack –Quicker Response because-Memory cells “remember” pathogen from before and attack it immediately –Reason for vaccinations

Antibody Response After Exposure to Antigen

Specific Immunity: B cells (3rd line of defense continued)

Antibodies are Produced by B Lymphocytes

How do B cells respond to foreign Invaders? Humoral immunity response AKA: Antibody-Mediated Response- “humors”- fluid of blood or lymph B cells mature in red bone marrow extracellular, bind to bacteria, toxins, free viruses before they enter cells useless against viruses, TB, other invaders that slip into cells B cells create plasma cells which release antibodies

Antibody Mediated Response cont. Apoptosis –Programmed cell death (“Falling away”). –Human body makes 100 million lymphocytes every day. If an equivalent number doesn’t die, will develop leukemia. –B cells that do not encounter stimulating antigen will self-destruct and send signals to phagocytes to dispose of their remains. –Many virus infected cells will undergo apoptosis, to help prevent spread of the infection.

Clonal Selection of B Cells is Caused by Antigenic Stimulation

How do B cells respond to foreign Invaders? Steps of B cell response 1.Pathogen (foreign antigen) enters tissue. 2. macrophage engulfs foreign pathogen and displays antigen 3. Helper T cell joins with antigen through “lock and key” and releases cytokines

4. B cell becomes activated (turn on robot and program it to kill one thing/pathogen) because of chemical signals 5. B cell proliferates. (clone robots to kill a bunch of the same thing/pathogen) 6. B cells differentiate into plasma cells and memory cells. (split your army)

7. Plasma cells secrete antibodies to attack the pathogen and stop the reproduction (why we call it antibody mediated response) 8. Memory cells will circulate through the body ready for a 2 nd attack (why is this advantageous?)

How do T cells respond to foreign invaders? Cellular-Immune Response AKA: Cell-mediated Immunity - Cell to cell contact, lymphocyte response –Genes are receptors, NOT antibodies –T- cells mature in Thymus –More diverse and complex –Virus infected, bacteria infected, cancer cells, and cells of foreign grafts are destroyed, inside of cells

Cell Mediated Immunity is Carried Out by T Lymphocytes

How do T cells respond to foreign invaders? Steps for T cell response: 1.Pathogen (foreign antigen) enters tissue 2. Macrophage phagocytizes pathogen 3.Macrophage displays foreign antigen on cell surface.

(reference your diagram) Steps… 4. Helper T cell joins with antigen through lock and key (puzzle pieces fit) 5. Helper T cell secretes cytokines (sprinkles)

(reference your diagram) Steps… 6.T cell becomes activated- enzymes activate lymphocyte response 7.T cells proliferate- make more of themselves 8.T cells differentiate into cytotoxic T cells and memory T cells

Steps… 9. Cytotoxic T cells bind with pathogen and release substances that destroy pathogen. cyto= toxic= 10. Memory cells will circulate through the body ready for a 2 nd attack/exposure

Left Side Assignments Page 84-Lines of Defense Foldable –List characteristics of each defense –List similarities at the bottom –Use pp. 71, 83, 85 Page 86-T cell response to an antigen –Follow directions at the top –Apply the steps in your notes to what is happening in the sections of the picture –Some of the steps in your notes are represented by one part of the diagram (apply your notes to the diagram) Page 88-B cell response to an antigen –Follow directions at the top –Apply the steps in your notes to what is happening in the sections of the picture –Some of the steps in your notes are represented by one part of the diagram (apply your notes to the diagram)

Warm-up Fill in the blanks Underline the word with purple if it is a name of a cell. Underline the word in orange if it is a chemical/substance produced by a cell. Shade the bubble blue if it is a general defense response (1 st /2 nd line of defense) Shade the bubble red if it is a T cell response Shade the bubble green if it is a B cell response.

Warm-up 4/2/13 Fill in the blanks Underline the word with purple if it is a name of a cell. Underline the word in orange if it is a chemical/substance produced by a cell. Shade the bubble blue if it is a general defense response (1 st /2 nd line of defense) Shade the bubble red if it is a T cell response Shade the bubble green if it is a B cell response.

Left Side Assignments Page 70-Compare and contrast specific immunity and nonspecific immunity (Today’s assignment) –This is a review assignment-you will need multiple pages of notes to answer –Your choice of graphic organizer Page 82-Extra Credit Assignment –Compare and contrast the immune system and the integumentary system. –Your choice of graphic organizer.