Chapter 16Lymphatic System and

Immunity

• vessels that assist in circulating fluids• • transports fluid to the bloodstream• transports fats to bloodstream•

16-2

Lymphatic Pathways

16-3

Lymphatic Pathways

16-4

Lymphatic Capillaries

• microscopic• closed-ended tubes• in interstitial spaces of most tissues

16-5

Lymphocytes.mov

Lymphatic Vessels

• merge into lymphatic trunks• lymphatic trunks drain into collecting ducts

16-6

Tissue Fluid and Lymph

Lymph• tissue fluid that has entered a lymphatic capillary

16-8

Spleen

• largest lymphatic organ• upper left abdominal quadrant• sinuses filled with blood

16-15

Body Defenses Against Infection

• pathogen• • bacteria, viruses, etc

• innate defenses • general defenses•

• adaptive defenses• immunity• • carried out by lymphocytes

16-16

Innate Defenses

• Species Resistance• resistance to certain diseases to which other species are susceptible

• Mechanical Barriers• skin• mucous membranes

• Fever •

• increases phagocytic activity

16-17

Innate Defenses

• Chemical Barriers• enzymes in various body fluids• • • interferons• defensins• collectins

• Natural Killer Cells• type of lymphocyte• lysis of viral-infects cells and cancer cells

16-18

Innate Defenses

• Inflammation• response to injury• • promotes healing• blood vessels dilate• • white blood cells attracted to area• clot forms• fibroblasts arrive• phagocytes are active

• Phagocytosis• neutrophils• monocytes• macrophages• destruction of foreign particles

16-19

Nonspecific Immunitiy.movMachrophage.mov

Fevor.movInterferion.mov

Immunity

• resistance to particular pathogens or to their toxins or metabolic by-products• • antigens elicit immune responses

16-20

Lymphocyte Functions

• T cells• secrete lymphokines

• help activate T cells• cause T cell proliferation• activate cytotoxic T cells• stimulate leukocyte production• stimulate B cells to mature• activate macrophages

• secrete toxins that kill cells• secrete growth-inhibiting factors• secrete interferon• cellular immune response

16-23

T cells.mov

Lymphocyte Functions

• B cells• differentiate into plasma cells

• produce antibodies

16-24

T Cells

•types of T cells• T cell• T cell• T cell

16-25

T Cell and B Cell Activation

16-26

B Cell Proliferation

16-27

Antibody Actions

• agglutination• precipitation• neutralization• activation of complement

16-31

Antibodies.mov

Actions of the Complement System

16-32Vacination.mov

Allergic Reactions

Type I• • hives• hay fever• asthma• eczema• gastric disturbances• anaphylactic shock

16-35

Allergic Reactions

Type II• antibody-dependent cytotoxic reaction• takes 1-3 hours to develop• transfusion reaction

Type III• immune-complex reaction• takes 1-3 hours to develop• antibody complexes cannot be cleared from body• damage of body tissues

16-36

Allergic Reactions

Type IV• delayed-reaction allergy• results from repeated exposure to allergen• eruptions and inflammation of the skin• takes about 48 hours to occur

16-37

Transplantation and Tissue Rejection

• corneas• kidneys• livers• pancreases• hearts• bone marrow• skin

Tissue rejection reaction•

• important to match MHC antigens•

16-38

Graft Types

• Isograft – identical twin• Autograft - self• Allograft – same species• Xenograft – different species

16-39

Autoimmunity

•

Autoimmune Disorders• glomerulonephritis• Graves disease• type I diabetes• hemolytic anemia• myasthenia gravis• rheumatic fever• rheumatic arthritis• lupus

16-40

Life-Span Changes

• immune system declines early in life when thymus gland shrinks• higher risk of infections• antibody response to antigens becomes slower

16-41

Clinical Application

Immunity Breakdown: AIDS

• recurrent fever• weakness• weight loss• caused by HIV (human immunodeficiency virus)• HIV impair macrophages and helper T cells• later in infection, HIV impairs cytotoxic T cells• HIV mutates quickly• immune system cannot keep up with HIV

16-42