Lecture AP Biology Chapter 43 The immune system

Upon completion of this lesson, the successful participant will be able to: Distinguish between innate and acquired immunity; name and describe four types of phagocytic cells; describe the inflammation response; distinguish between the following pairs of terms: antigens and antibodies; antigen and epitope; B lymphocytes and T lymphocytes;...

Chapter 43 Warm-Up

1 Define the following terms:

– Pathogen

– Antigen

– Antibody

– Allergen

– Vaccine

and T cells mature?

Ch 43 Review Warm-Up

1 What is the difference between innate vs

adaptive immunity?

2 Contrast the functions of B cells and T

cells.

3 How are antigens recognized by immune

system cells?

4 What are memory cells?

5 How does HIV affect the immune

system?

THE IMMUNE SYSTEM

Chapter 43

What you must know:

• The differences between B and T cells relative

to their activation and actions.

system cells

• The differences in humoral and cell-mediated immunity

• Why Helper T cells are central to immune

responses

Types of Immunity

Innate Immunity Adaptive Immunity

• Non-specific

• All plantsplants & animalsanimals

• Pathogen-specific

• Only in vertebratesvertebrates

• Involves B and T cells

Plant Defenses

• Nonspecific responses

• Receptors recognize pathogen molecules and trigger defense responses

– Thicken cell wall, produce antimicrobial

compounds, cell death

• Localize effects

Pathogens (such as bacteria, fungi, and viruses)

INNATE IMMUNITY

(all animals)

• Rapid response

Recognition of traits shared

by broad ranges of pathogens, using a small set of receptors

•

Recognition of traits specific to particular pathogens, using a vast array of receptors

•

• Slower response

Barrier defenses:

Skin Mucous membranes Secretions

Internal defenses:

Phagocytic cells Natural killer cells Antimicrobial proteins Inflammatory response

Humoral response:

Antibodies defend against infection in body fluids.

Cell-mediated response:

Cytotoxic cells defend against infection in body cells.

ADAPTIVE IMMUNITY

(vertebrates only)

Figure 43.2

Barrier Defenses:

•Skin

•Mucous membranes

•Lysozyme (tears,

saliva, mucus)

Inflammatory Response:

• Mast cells release histamine 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)

Natural Killer Cells:

•Virus-infected and cancer cells

Antimicrobial Proteins:

•Interferons (inhibit viral reproduction)

•Complement system (~30 proteins,

membrane attack complex)

Innate Immunity

(non-specific)

Innate Immunity

(non-specific)

Phagocytosis

Inflammatory Response

Lymphatic System: involved in adaptive immunity

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

• Antigen: substance that elicits lymphocyte

response

• Antibody (immunoglobulin – Ig): protein made by

B cell that binds to antigens

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 I

• Class II: displayed by immune cells; “non-self”Class II

Humoral Immune Response

(antibodies)

Humoral Immune Response

(antibodies)

Cell-Mediated Immune

Response

(T Cells)

Cell-Mediated Immune

Response

(T Cells)

Antigen-presenting cell

Helper T cell

cell

Plasma cell

Infected cell

Antibodies

Identify and destroy tag for

destruction

Immunological Memory

• Primary immune response: 1st exposure to antigen

• Memory cells:

– Secondary immune response: repeat exposure  faster, greater response

Antigen receptor

Antibody

Plasma cells Memory cells

B cells that

differ in

antigen

specificity

Figure 43.14

• Immunizations/vaccines : induce immune

memory to nonpathogenic microbe or toxin

• Passive immunity : via antibodies in breast milk

• Allergies : hypersensitive responses to

harmless antigens

– Lupus, rheumatoid arthritis, Type I diabetes, multiple sclerosis

• HIV : infect Helper T cells

– AIDS = severely weakened immune system