B11-5-02 Immune Response

3rd Line – Immune Response B11-5-02 – Body’s response to viruses/bacteria

Immune System Video

The 3 Lines of Defense The 1st line of Defense 

Barriers

The 2nd line of Defense 

Inflammatory response

The 3rd line of Defense 

Immune response

Immune system distinguishes “self” from “non-self” 

Do not react with our own cells

Generates specific response to specific invaders Builds up resistance against Pathogens 

Antigen

Tailored to an individual threat

Most effective 

Memory component Improves response time

Immune Response Two types of specific immune response  

Antibody-mediated Cell-mediated

Antibody-Mediated Immunity

Antibody-Mediated Immunity Production of antibodies specific to a given antigen 

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Antibodies bind to the antigens on invaders and kill or inactivate them Antigens are molecules that cause antibody production

Response provided by B cells (lymphocytes derived from bone marrow)

Lymphocyste Video

In Response to Infection A few days after an infection 

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Antigens cause the production of large amount of the antibody capable of interacting with it Specific antibodies bind specific antigens

Antibodies Antibodies bind antigens in a lock-and-key fashion 

Forming antigen-antibody complex

Type of protein 

Immunoglobulin

Y shaped molecules with  

Two heavy chains Two light chains

Antibodies Cont. Identify Antigens as either  

Self Nonself

Bind non-self antigens clumping them together making them inactive

Antibodies Cont. Body only has antibodies for pathogens that a host has encountered When a new pathogen invades the body, B-cells “learn” about new antigens and develop appropriate antibodies The B-Cells then circulate though the body, releasing antibodies that bind to new antigen

Antibodies Video 1

Antibodies Video 2

Antigens Protein or polysaccharide that is present on the plasma membrane

Cell-Mediated Immunity

Cell-mediated Immunity Require direct physical contact with antigens Does not involve the production of antibodies Response provided by T-Cells (lymphocytes derived from the thymus) 

Four types

1. Cytotoxic (Killer) T-Cells Defend the body by destroying   

Foreign cells Infected cells Cancerous cells

Recognizes viral antigens on plasma membrane of host cell Attaches to plasma membrane of host cell

Secrete enzymes that digest host plasma membrane 

Punching holes

Infected cell’s cytoplasm leaks out and the cell dies The dead cell and its contents are removed by phagocytes

2. Helper T-Cells Regulate immune response by …  

Secreting messenger proteins Direct contact with other cells

Helps Killer T-Cells and B-Cells to perform their function Are destroyed by the HIV virus in patients with Acquired Immune Deficiency Syndrome (AIDS)

3. Suppressor T Cells Reduce the immune response of B cells and T cells to keep them in check

4. Memory T Cells Remain in the body awaiting the reintroduction of the antigen

Grab a Text Read and Make Notes 

13.3 INDUCED IMMUNITY Active Immunity (250) Passive Immunity (251)