1. Defenses Against Infection Human Immune System

2. KEY CONCEPT The immune system has many responses to pathogens and foreign cells.

3. The job of the immune systems is to fight off pathogens & infections. Skin is a physical barrier to infection. Mucous Membranes trap pathogens entering the body.

4. Nonspecific responses First Line of Defense: Skin – few pathogens can penetrate the layers of dead skin cells Mucous membranes

5. Second Line of Defense: Inflammation - blood vessels become leaky. Histamines & interferons Fever - body temperature increases Slows growth of pathogens Low fevers stimulate white blood cells to mature.

6. Cells of the immune system produce SPECIFIC RESPONSES Specific Immune response: Antigens are surface proteins on pathogens. Each pathogen has a different antigen. antigens

7. Recognizing Self Your body’s white blood cells use antigens to recognize “self” versus “other”. Your body then works to inactivate or destroy “other”

8. Attacking Invaders/Pathogens Phagocytes (like Pacman) consume pathogens and present the pathogen’s antibodies to other white blood cells.

9. Antibodies Produced by lymphocyte Bind to foreign antigens Each antibody is specific for a particular antigen Body can make 10B different antibodies!!! Tag foreign cells for destruction by other WBCs

10. Lymphocytes B – Cells Made in bone marrow Each recognizes a single antigen Once activated they produce Memory B cells & plasma cells Memory B cells remain after infection Memory B cells allow a rapid response during re-infection

11. Lymphocytes T – Cells Made in bone marrow, mature in thymus Each recognizes a single antigen Helper T-cells Activate B-cells Activate killer T-cells Produce memory T-cells

13. Vaccines Allow person to acquire immunity without contracting disease Contain the antigen of a weakened pathogen Does not cure a person who is sick

14. –stimulates a specific immune response –causes memory B & T cells to be produced –allows immune system to respond quickly to infection next time –has such a fast response, a person will not get sick A memory B cell is stimulated when the real pathogen binds to it. 2 The B cell quickly activates and makes antibodies that fight the pathogens before you get sick. 3 Antigens in a vaccine trigger an immune response, and memory B cells are made. 1 memory B cells Vaccination provides immunity. Memory B-cells