1. Chapter 18 Warm-Up Define the following terms:
Pathogen
Antigen
Antibody
Allergen
Vaccine
What are lymphocytes? Where do B cells and T cells mature?

2. Ch.18 Review Warm-Up
What is the difference between innate vs. adaptive immunity?
Contrast the functions of B cells and T cells.
How are antigens recognized by immune system cells?
What are memory cells?
How does HIV affect the immune system?

3. Chapter 18
THE IMMUNE SYSTEM

4. What you must know: Several elements of an innate immune response
The differences between B and T cells relative to their activation and actions.
How antigens are recognized by immune system cells
The differences in humoral and cell-mediated immunity
Why Helper T cells are central to immune responses

5. Types of Immunity Innate Immunity Adaptive Immunity Non-specific
All plants & animals
Pathogen-specific
Only in vertebrates
Involves B and T cells

6. Plant Defenses Nonspecific responses
Receptors recognize pathogen molecules and trigger defense responses
Thicken cell wall, produce antimicrobial compounds, cell death
Localize effects

7. Pathogens (such as bacteria, fungi, and viruses)
Figure 43.2
Pathogens (such as bacteria, fungi, and viruses)
INNATE IMMUNITY (all animals)
Barrier defenses:
Skin Mucous membranes Secretions
Recognition of traits shared by broad ranges of pathogens, using a small set of receptors •
Internal defenses:
Phagocytic cells Natural killer cells Antimicrobial proteins Inflammatory response
• Rapid response
Figure 43.2 Overview of animal immunity.
ADAPTIVE IMMUNITY (vertebrates only)
Humoral response:
Antibodies defend against infection in body fluids.
Recognition of traits specific to particular pathogens, using a vast array of receptors •
Cell-mediated response:
Cytotoxic cells defend against infection in body cells.
• Slower response

8. Innate Immunity Antimicrobial Proteins: Barrier Defenses:
Interferons (inhibit viral reproduction)
Complement system (~30 proteins, membrane attack complex)
Barrier Defenses:
Skin
Mucous membranes
Lysozyme (tears, saliva, mucus)
Innate Immunity
(non-specific)
Natural Killer Cells:
Virus-infected and cancer cells
Inflammatory Response:
Mast cells release histamine
Blood vessels dilate, increase permeability (redness, swelling)
Deliver clotting agents, phagocytic cells
Fever
Phagocytic WBCs:
Neutrophils (engulf)
Macrophage (“big eaters”)
Eosinophils (parasites)
Dendritic cells (adaptive response)

9. Phagocytosis

10. Inflammatory Response

11. Lymphatic System: involved in adaptive immunity

12. Adaptive Response
Lymphocytes (WBCs): produced by stem cells in bone marrow
T cells: mature in thymus
helper T, cytotoxic T
B cells: stay and mature in bone marrow
plasma cells  antibodies

13. Antigen: substance that elicits lymphocyte response
Antibody (immunoglobulin – Ig): protein made by B cell that binds to antigens

14. Major Histocompatibility Complex (MHC)
Proteins displayed on cell surface
Responsible for tissue/organ rejection (“self” vs. “non-self”)
B and T cells bind to MHC molecule in adaptive response
Class I: all body cells (except RBCs)
Class II: displayed by immune cells; “non-self”

15. Cell-Mediated Immune Response Humoral Immune Response
Antigen-presenting cell
Cell-Mediated Immune Response
(T Cells)
Humoral Immune Response
(antibodies)
Helper T cell
B cell
Cytotoxic T cell
Plasma cell
tag for destruction
Identify and destroy
Infected cell
Antibodies

16. Immunological Memory Primary immune response: 1st exposure to antigen
Memory cells:
Secondary immune response: repeat exposure  faster, greater response

17. B cells that differ in antigen specificity Antigen Antigen receptor
Figure 43.14
B cells that differ in antigen specificity
Antigen
Antigen receptor
Figure Clonal selection.
Antibody
Memory cells
Plasma cells

20. Passive immunity: via antibodies in breast milk
Immunizations/vaccines: induce immune memory to nonpathogenic microbe or toxin
Passive immunity: via antibodies in breast milk
Allergies: hypersensitive responses to harmless antigens
Autoimmune Diseases:
Lupus, rheumatoid arthritis, Type I diabetes, multiple sclerosis
HIV: infect Helper T cells
AIDS = severely weakened immune system