18
Chapter 33-Immune System

Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Embed Size (px)

Citation preview

Page 1: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Chapter 33-Immune System

Page 2: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

• Innate immunity-born with• Acquired immunity-develops on exposure

Page 3: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Lines of Defense

Nonspecific Defense Mechanisms……

Page 4: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Phagocytic and Natural Killer CellsRecognize unfamiliar receptors—non-

self.

• Neutrophils– 60-70% WBCs; engulf and destroy microbes

at infected tissue

• Monocytes– 5% WBCs; develop into….

• Macrophages– enzymatically destroy microbes

• Eosinophils– 1.5% WBCs; destroy large parasitic invaders

(blood flukes)

• Natural killer (NK) cells– destroy virus-infected body cells &

abnormal cells

Page 5: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

The Inflammatory Response

1- Tissue injury; release of chemical signals~ • histamine (basophils/mast cells): causes Step 2... • prostaglandins: increases blood flow & vessel permeability

2/3- Dilation and increased permeability of capillary~ • chemokines: secreted by blood vessel endothelial cells mediates phagocytotic migration of WBCs

4- Phagocytosis of pathogens~ • fever & pyrogens: leukocyte-released molecules increase body temperature

Page 6: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Specific Defense Mechanisms

Lymphocyctes• Originate from stem cells in

bone marrow.• Activated by cytokines from

phagocytes.• Antigen-any foreign molecule

recognized by a lymphocyte.• Antigen receptor-plasma

membrane, recognizes specific antigens.

Types:B cellsT cells

Page 7: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Clonal selection of lymphocytes• Need lots of copies of

lymphocyte• Effector cells: short-lived cells

that combat the antigen• Memory cells: long-lived cells

that bear receptors for the antigen

• Clonal selection: antigen-driven cloning of lymphocytes

• “Each antigen, by binding to specific receptors, selectively activates a tiny fraction of cells from the body’s diverse pool of lymphocytes; this relatively small number of selected cells gives rise to clones of thousands of cells, all specific for and dedicated to eliminating the antigen.”

Page 8: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Induction of Immune Responses• Primary immune response: lymphocyte proliferation and

differentiation the 1st time the body is exposed to an antigen• Secondary immune response: immune response if the

individual is exposed to the same antigen at some later time~ Immunological memory

Page 9: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Types of immune responses

Page 10: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Antibody Structure & Function• Antibody-proteins that bind to particular antigens and marks

it for elimination—also called immunoglobulin• Epitope: region on antigen surface recognized by antibodies• 2 heavy chains and 2 light chains joined by disulfide bridges• Antigen-binding site (variable region)

Page 11: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

5 classes of Immunoglobins

Page 12: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

MHC molecules

• Major HistocompatibilityComplex- Cell surface proteins that bind to antigens

Class 1-bind foreign antigens produced by an infected or cancerous cellrecognized by cytotoxic T cells

Class 2-Antigen presentation• Bind to antigens inside the cell and bring them

outside the cell so they can be recognized by the immune system.

• Recognized by helper T cells

Page 13: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Cell-mediated: cytotoxic T cells• Destroy cells infected by intracellular pathogens and cancer cells

Page 14: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Helper T cells• Recognizes presented antigen and activates nearby B

cells and cytotoxic Tcells• CD4-surface protein on HTC’s that bind them to the

infected cell

Page 15: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Humoral response: B cells

Page 16: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Antibody-mediated Antigen Disposal

Page 17: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Immunity in Health & Disease

• Active immunity/natural: conferred immunity by recovering from

disease• Active immunity/artificial: immunization

and vaccination; produces a primary response

• Passive immunity: transfer of immunity from one individual to another

• natural: mother to fetus; breastmilk

• • artificial: rabies antibodies• ABO blood groups (antigen presence)• Rh factor (blood cell antigen); Rh- mother

vs. an Rh+ fetus (inherited from father)

Page 18: Chapter 33-Immune System. Innate immunity-born with Acquired immunity-develops on exposure

Abnormal immune function• Allergies (anaphylactic shock): hypersensitive responses to environmental antigens

(allergens); causes dilation and blood vessel permeability (antihistamines); epinephrine

• Autoimmune disease: multiple sclerosis, lupus, rheumatoid arthritis, insulin-dependent diabetes mellitus

• Immunodeficiency disease: SCIDS (bubble-boy); A.I.D.S.