The Immune System Chapter 24

External Defenses Prevents infection Block, trap or filter out Skin Nostril hairs Ear wax Mucus Block, trap or filter out

Internal Defenses - WBC Natural killer cells swarming cancer cell (yellow) Phagocytic cell (yellow) engulfing a foreign cell

Inflammatory Response

Lymphatic System https://www.youtube.com/watch?v=QD9AdNXSQe4

Lymphatic and Immune Systems Because the lymphatic vessels penetrate all tissues, lymph can pick up pathogens from anywhere in the body

Recognizing antigens – B cells

Recognizing antigens – T cells

1 Antigens on the surface of a pathogen B cells that recognize Figure 24.6-s1 Antigens on the surface of a pathogen 1 B cells that recognize different antigens Antigen receptor on cell surface Figure 24.6-s1 Clonal selection during the first exposure to an antigen (step 1)

1 2 Antigens on the surface of a pathogen B cells that recognize Figure 24.6-s2 Antigens on the surface of a pathogen 1 B cells that recognize different antigens Antigen receptor on cell surface 2 Figure 24.6-s2 Clonal selection during the first exposure to an antigen (step 2)

1 2 3 Antigens on the surface of a pathogen B cells that recognize Figure 24.6-s3 Antigens on the surface of a pathogen 1 B cells that recognize different antigens Antigen receptor on cell surface 2 Figure 24.6-s3 Clonal selection during the first exposure to an antigen (step 3) 3 Clone of effector B cells Antibodies

1 2 4 3 Antigens on the surface of a pathogen B cells that recognize Figure 24.6-s4 Antigens on the surface of a pathogen 1 B cells that recognize different antigens Antigen receptor on cell surface 2 4 Clone of memory B cells Figure 24.6-s4 Clonal selection during the first exposure to an antigen (step 4) 3 Clone of effector B cells Antibodies

Antibody bound to antigens on the surface of pathogens Antigen- Figure 24.8 Antigen on the surface of a pathogen Antigen- binding site of antibody Nucleus Effector B cell Antigens on the surface of pathogens Antibodies Antigen on the surface of a pathogen Antibody bound to antigens on the surface of pathogens Antigen- binding site

(a) Antibodies block a virus from entering a body cell. Figure 24.9-1 Virus entering a body cell Antibodies preventing viral attachment and entry Viral attachment protein Virus Virus Body cell receptor Antibody Figure 24.9-1 The binding of antibodies to antigens blocks or helps to destroy an invader (part 1: antibodies block virus entry) Body cell Body cell (a) Antibodies block a virus from entering a body cell.

(b) Antibodies enhance phagocytosis. Figure 24.9-2 Antibody Bacteria Antibody binding causes bacteria to clump. A clump of bacteria is easily engulfed by a phagocyte. Figure 24.9-2 The binding of antibodies to antigens blocks or helps to destroy an invader (part 2: antibodies enhance phagocytosis) Phagocyte (b) Antibodies enhance phagocytosis.

1 2 3 Cytotoxic T cell binds to infected cell, becoming activated. Figure 24.10 Proteins Foreign antigen Infected cell Activated cytotoxic T cell Proteins 1 Cytotoxic T cell binds to infected cell, becoming activated. 2 3 Proteins that trigger cell death enter the infected cell. Infected cell dies. Figure 24.10 The cytotoxic T cell response

Antibody concentration Figure 24.11 Secondary immune response to antigen Second exposure to antigen First exposure to antigen Antibody concentration Primary immune response to antigen Figure 24.11 Antibody production during the two phases of the B cell response Antibodies 7 14 21 28 35 42 49 56 Time (days)

Immune Disorders - Allergies

Helpful review videos https://www.youtube.com/watch?v=zQGOcO UBi6s https://www.youtube.com/watch?v=z3M0vU 3Dv8E Polio documentary https://www.youtube.com/watch?v=gE4ef0yQZRU& t=1972s