Immune System

A Boo Boo lets in germs

Like…Bacteria

Or a virus

A germ is still a germ…. 1. Pathogen=agent that causes disease 2. Antigen= foreign particle that triggers an immune response immune response - often they are proteins on the surface of viruses and bacteria

Your Body’s Defenses Against Disease Nonspecific Defenses: Attack all pathogens and antigens the same way Nonspecific Defenses: Attack all pathogens and antigens the same way Specific Defenses: Immune Response – Attack pathogens that get past the nonspecific defenses Specific Defenses: Immune Response – Attack pathogens that get past the nonspecific defenses

Nonspecific Defenses This means that the identity of the pathogen/antigen is not important. The response is the same if a bacteria, virus, splinter or bullet invades the body.

Nonspecific Defenses First Line Defenses Skin: Forms a physical barrier to pathogens Skin: Forms a physical barrier to pathogens -oils and sweat make skin acidic – inhibits the growth of pathogens -lysozyme-enzyme found in sweat and tears digests bacterial cell walls -lysozyme-enzyme found in sweat and tears digests bacterial cell walls Mucus Membranes-layers of tissue which secrete mucus Mucus Membranes-layers of tissue which secrete mucus - found in body openings and the respiratory - found in body openings and the respiratory system system - mucus traps pathogens - mucus traps pathogens

Nonspecific Defenses Second Line Defenses Inflammatory Response Inflammatory Response Damaged cells release histamines – chemical cry for help Damaged cells release histamines – chemical cry for help - histamines cause blood vessels to dilate (open) bringing - histamines cause blood vessels to dilate (open) bringing blood to the area. blood to the area. - the dilated blood vessels become leaky releasing fluid and white blood cells in the infected area - the dilated blood vessels become leaky releasing fluid and white blood cells in the infected area - causes swelling and redness in the damaged area - causes swelling and redness in the damaged area - pus – fluid and dead cells forms - pus – fluid and dead cells forms White Blood cells White Blood cells - Macrophages – “Big Eaters” engulf and kill pathogens - Macrophages – “Big Eaters” engulf and kill pathogens - Neutrophils- engulf bactera and release chemicals that kill the bacteria and themselves. - Neutrophils- engulf bactera and release chemicals that kill the bacteria and themselves. - Natural Killer Cells – recognize and kill virus infected - Natural Killer Cells – recognize and kill virus infected cells and tumors cells and tumors

Textbook page 925 Histamines are released Blood vessels dilate Histamines are released Blood vessels dilate and leak and leak

Macrophage

Nonspecific Defenses Second Line Defenses (continued) Temperature Response - Fever – Temperature Response - Fever – -Body temp increases in response to infection -pathogenic bacteria don’t grow well at higher temp -pathogenic bacteria don’t grow well at higher temp Proteins Proteins - Complement Proteins: kill pathogens by punching a hole in the cell membrane - Complement Proteins: kill pathogens by punching a hole in the cell membrane - Intrerferon: a protein released by cells infected by viruses - Intrerferon: a protein released by cells infected by viruses -causes nearby cells to release an enzyme preventing the virus -causes nearby cells to release an enzyme preventing the virus from reproducing from reproducing

Fevers help eliminate pathogens

Specific Defenses Third Line of Defense Third Line of Defense Specific Defenses Specific Defenses - identity of pathogen/ - identity of pathogen/ antigen must be known antigen must be known - the specific immune - the specific immune response is tailored to response is tailored to the specific pathogen the specific pathogen

Specific Defenses Macrophage Links Nonspecific to Specific When a macrophage engulfs a pathogen, it displays the viral antigen on its surface The antigen is joined to a MHC (Major Histocompatibility Complex) The MHC is a protein on the surface of all vertebrate cells The anitgen must be bound to the MHC for the Helper T Cell to recognize it

Specific Defenses Helper T Cells Receptor proteins on helper T cells (T H ) bind to viral antigens displayed on the macrophage Receptor proteins on helper T cells (T H ) bind to viral antigens displayed on the macrophage causes macrophage to release Interleukin1 causes macrophage to release Interleukin1 Interleukin1 activates Interleukin1 activates the helper T cells (T H ) the helper T cells (T H )

Specific Defenses Helper T Cells continued Activated helper T cells (T H ) release proteins called cytokines which activate cytotoxic T cells (T C ) and B cells Activated helper T cells (T H ) release proteins called cytokines which activate cytotoxic T cells (T C ) and B cells The activated (T C ) and B cells begin to divide The activated (T C ) and B cells begin to divide

Specific Defenses Cell Mediated Response Receptor proteins on the Receptor proteins on the cytotoxic T cells (T C ) bind to cytotoxic T cells (T C ) bind to viral antigens displayed by viral antigens displayed by infected cells infected cells Cytotoxic T cells (T C ) punch a Cytotoxic T cells (T C ) punch a hole in the cell’s membrane hole in the cell’s membrane Your body produces many Your body produces many cytotoxic T cells (T C ) cytotoxic T cells (T C ) - each specific to a particular antigen

Specific Defenses Antibody Mediated Response B cells divide and develop into B cells divide and develop into plasma cells plasma cells Plasma cells release large numbers Plasma cells release large numbers of antibodies of antibodies Antibodies bind to antigens on Antibodies bind to antigens on pathogens pathogens Antibodies cause pathogens to clump Antibodies cause pathogens to clump holding them until macrophages holding them until macrophages can engulf them can engulf them Antibodies are specific to a particular pathogen-your body produces the antibodies in response to infection Antibodies are specific to a particular pathogen-your body produces the antibodies in response to infection

The Specific Defense has two phases Primary Immune Response: Primary Immune Response: - Occurs when the body has never encountered a pathogen /antigen before. - Occurs when the body has never encountered a pathogen /antigen before. -Immune system goes through all of the steps -After the threat has passed, MEMORY Cells are made. -After the threat has passed, MEMORY Cells are made. Secondary Immune Response: Secondary Immune Response: The next time the pathogeninvades MEMORY Cells identify the invader and a massive volume of antibodies are released, destroying the invader before you feel ill. You are immune! You are immune!

Vaccines Polio ,000 cases in the US 3000 fatalities 1955 Salk vaccine 1979 eliminated in US

How do vaccines work? Vaccines are made up of weakened viral particles. Vaccines are made up of weakened viral particles. The weakened particles stimulate a small number of antibodies and memory cells to be produced. Primary Immune Response The weakened particles stimulate a small number of antibodies and memory cells to be produced. Primary Immune Response When a the pathogen attacks, the antibody production is larger. When a the pathogen attacks, the antibody production is larger. Secondary Immune Response Secondary Immune Response

Immune Response

Vocabulary Pathogen B cells T cells Pathogen B cells T cells Macrophages Macrophages Nonspecific Defense Nonspecific Defense Vaccines Vaccines Primary Immune Response Primary Immune Response Secondary Immune Response Secondary Immune Response