1. The Immune System
Chapter 24

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

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

4. Inflammatory Response

5. Lymphatic System

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

7. Recognizing antigens – B cells

8. Recognizing antigens – T cells

9. 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)

10. 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)

11. 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

12. 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

14. 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

15. (a) Antibodies block a virus from entering a body cell.
Figure
Virus entering a body cell
Antibodies preventing viral attachment
and entry
Viral
attachment
protein
Virus
Virus
Body cell
receptor
Antibody
Figure 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.

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

17. 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 The cytotoxic T cell response

18. 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 Antibody production during the two phases of the B cell response
Antibodies 7 14 21 28 35 42 49 56
Time (days)

19. Immune Disorders - Allergies

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