1. Chapter 24
The Immune System

2. About this Chapter
Anatomy & function of immune system, organs, & cells
How the body defends itself
Non-specific body defenses
Specific defenses that target one pathogen
Combined defenses against bacteria and viruses
Allergies and autoimmune problems

3. Immune System Functions: Overview of Defenses
Scavenge dead, dying or abnormal (cancerous) body cells
Protect from pathogens & foreign molecules
Parasites
Bacteria
Viruses

12. Immune System Functions: Overview of Defenses
Figure 24-1: Viruses

13. HIV or Human Immunodeficiency Virus

17. Life Cycle

18. Infectious Causes of Gastroenteritis.
Bok K, Green KY. N Engl J Med 2012;367:

19. Genomic Organization and Atomic Structure of the Norovirus Capsid.
Figure 1. Genomic Organization and Atomic Structure of the Norovirus Capsid. The RNA genome of the prototype norovirus strain, Norwalk virus (shown at the top), is organized into three open reading frames (ORF1, ORF2, and ORF3) that encode the designated nonstructural and structural proteins. Most diagnostic primers used in reverse-transcriptase–polymerase-chain-reaction assay target conserved areas in the RNA-dependent RNA polymerase region (NS7POL). VP1, the major capsid protein (shown below), is further organized into the N-terminal (N), shell (S), and protruding (P) domains defined by the indicated VP1 amino acid residues. The P2 region of the P domain (blue) is exposed on the surface of the capsid protein and is the site where histo–blood group antigens (HBGAs) (magenta) interact with the virion (dashed box). 5, 13
Bok K, Green KY. N Engl J Med 2012;367:

20. Body Defenses: Overview
Physical barriers: skin & epithelial linings & cilia
Chemical: acids, mucous & lysozymes
Immune defenses – internal
Innate, non-specific, immediate response (min/hrs)
Acquired – attack a specific pathogen (antigen)
Steps in Immune defense
Detect invader/foreign cells
Communicate alarm & recruit immune cells
Suppress or destroy invader

21. Lymphatic System: Overview of Immune Defense Organs & Cells
Bone marrow
Thymus
Lymph nodes
Spleen
Lymph vessels
Leukocytes:
(white blood cells – WBCs)

22. Lymphatic System: Overview of Immune Defense Organs & Cells
Figure 24-2 ab: Anatomy of the immune system

24. Key Cells & Overview of their Function in Immune Defense
Lymphocytes: helper, plasma, cytotoxic & natural killer (NK)
Basophils
Mast cells
Monocytes
Macrophages
Neutrophils
Eosinophils

25. Key Cells & Overview of their Function in Immune Defense
Figure 24-4: Cells of the immune system

26. Innate Immunity: Phagocytosis & Inflammation
Physical & chemical barriers
Phagocytosis: macrophages, neutrophils, NK cells
Engulf and digest recognized "foreign" cells – molecules
Inflammatory response

28. Innate Immunity: Phagocytosis & Inflammation
Figure 24-6: Phagocytosis

30. Cells of the Innate Immune System
The Innate Leukocytes include:
Natural killer cells
Mast cells
Eosinophils
Basophils
Phagocytic cells: including macrophages, neutrophils and dendritic cells, and
All these cells function within the immune system by identifying and eliminating pathogens that might cause infection

31. Chemical factors produced during inflammation
Histamine
Bradykinin
Serotonin
Leukotrienes
Prostaglandins
sensitize pain receptors, cause vasodilation of the blood vessels at the scene, and attract phagocytes, especially neutrophils

32. Inflammatory Response: Cytokines Signal Initiation
Histamines: from mast cells  swelling, edema, b. v . dilation
Interleukins: fever, b.v. gaps  WBC's & proteins  infection
Bradykinin: pain & swelling
Membrane attack complex proteins

33. Inflammatory Response: Cytokines Signal Initiation
Figure 24-8: Membrane attack complex

34. Acquired Immunity: Antigen-Specific Responses
Activate T lymphocytes: direct attack
Activate B lymphocytes to become:
Memory cells: 20 immune response to that antigen
Plasma cells: antibodies – attack that antigen

35. Antigen Presentation to Immature T Cells
Antigen presentation stimulates T cells to become either "cytotoxic" CD8+ cells or "helper" CD4+ cells. Cytotoxic cells directly attack other cells carrying certain foreign or abnormal molecules on their surfaces. Helper T cells, or Th cells, coordinate immune responses by communicating with other cells. In most cases, T cells only recognize an antigen if it is carried on the surface of a cell by one of the body’s own MHC, or major histocompatibility complex, molecules.

36. T Cell Dependent B Cell Activation
A TH2 cell (left), B cell (right), and several interaction molecules

37. B Cell Activation