Page 856 - Fundamentals of anatomy physiology

Chapter 22 The Lymphatic System and Immunity 843

Figure 22–27 Defenses against Bacterial and Viral Pathogens.

BACTERIA VIRUSES

Phagocytosis by
macrophages and APCs

Infection of Infection of or uptake
tissue cells by APCs

Antigen
presentation

Release of Appearance of antigen Antigen
interferons in plasma membrane presentation

Activation of Activation of
cytotoxic T cells helper T cells

Increased Stimulation Activation of Activation of
resistance to of NK cells cytotoxic T cells helper T cells
viral infection
Activation and spread Activation 22
of B cells of B cells

Antibody
production by
plasma cells

Opsonization Formation of Antibody
and phagocyte antigen-antibody production by
plasma cells
attraction complexes

Destruction of bacteria by Destruction of Destruction of
cell lysis or phagocytosis virus-infected cells viruses or

prevention of
virus entry into cells

a Defenses against bacteria involve phagocytosis b Defenses against viruses involve direct contact with virus-infected cells and
and antigen presentation by APCs. antigen presentation by APCs.

Checkpoint 20. Describe the structure of an antibody.
21. Which would be more negatively affected—the primary
18. Define sensitization.
response or the secondary response—by a lack of
19. A sample of lymph contains an elevated number of memory B cells for a particular antigen?
plasma cells. Would you expect the number of antibodies
in the blood to be increasing or decreasing? Why? See the blue Answers tab at the back of the book.