Chapter 16 Lymphatic System and Immunity. Lymphatic Pathways. Lymphatic Capillaries. network of vessels that assist in circulating fluids

Transcription

1 Chapter 16 Lymphatic System and Immunity network of vessels that assist in circulating fluids closely associated with the cardiovascular system transports excess fluid away from interstitial spaces transports fluid to the bloodstream transports fats to bloodstream help defend the body against diseases 1 Lymphatic Pathways 2 Lymphatic Capillaries microscopic closed-ended tubes in interstitial spaces of most tissues Parallel network of blood capillaries Similar in structure to blood capillaries Collect fluid from surrounding tissue, which becomes lymph Lacteals-specialized lymph capillaries in the lining of the small intestine that absorb digested fats 3 1

2 Lymphatic Vessels walls are similar but thinner than those of veins Have valves to prevent backflow composed of three layers endothelial lining (inner) smooth muscle (middle) connective tissue (outer) larger vessels lead to lymph nodes and then to larger lymphatic trunks 4 Lymphatic Trunks drain lymph from the lymphatic vessels named for the regions they serve lumbar intestinal intercostal bronchomediastinal subclavian jugular Join together to form collecting ducts 5 Collecting Ducts Right lymphatic duct drains lymph from the upper right side of the body Thoracic duct drains lymph from the rest of the body 6 2

3 Summary of Lymphatic Pathway 7 Tissue Fluid and Lymph Lymph tissue fluid that has entered a lymphatic capillary Lymph formation dependent on tissue fluid formation 8 Tissue Fluid Formation Tissue fluid originates from plasma contains water and dissolved substances contains smaller proteins which create colloid osmotic pressure 9 3

4 Lymph Formation increasing hydrostatic pressure within interstitial spaces forces tissue fluid into lymphatic capillaries resultant fluid is lymph this process prevents accumulation of excess tissue fluid or edema 10 Lymph Function absorption of dietary fats delivers fats to bloodstream collection of excess interstitial fluids delivers excess fluids to bloodstream delivers foreign particles to lymph nodes 11 Lymph Movement action of skeletal muscles respiratory movements smooth muscle in larger lymphatic vessels valves in lymphatic vessels 12 4

5 Located along the lymphatic pathway Contain large numbers of lymphocytes and macrophages Usually less than 25 cm long an bean shaped Lymph Nodes 13 Locations of Lymph Nodes May occur singly or in a group associated with mucous membranes of the respiratory and digestive tracts cervical region axillary region supratrochlear region inguinal region pelvic cavity abdominal cavity thoracic cavity 14 Lymph nodes Tonsils-partially encapsulated lymph nodules Peyer s patches-distal portion of the small intestine M cells-certain ingested molecules pass by transcytosis 15 5

6 Functions of Lymph Nodes filter potentially harmful particles from lymph immune surveillance by macrophages and lymphocytes areas of lymphocyte production 16 small in an adult, usually larger infancy and early childhood, then shrinks after puberty Subdivided by connective tissue in lobules, which contains many lymphocytes site of T lymphocyte production Thymus epithelial cells secretes thymosins 17 Spleen largest lymphatic organ located in upper left abdominal quadrant sinuses filled with blood contains two tissue types white pulp lymphocytes red pulp red blood cells lymphocytes macrophages 18 6

7 Major Organs of Lymphatic System 19 Body Defenses Against Infection pathogen disease causing agent bacteria, viruses, complex microorganisms, spores of multicellular organisms innate defenses general defenses protects against many pathogens adaptive defenses immunity more specific carried out by lymphocytes 20 Innate (Nonspecific) Defenses 21 7

8 Inflammation Response 22 Adaptive (Specific) Defenses or Immunity immunity - resistance to particular pathogens or to their toxins or metabolic by-products based on the ability to distinguish self from non-self antigens elicit immune responses 23 Antigens Molecules that can elicit an immune response proteins polysaccharides glycoproteins glycolipids most effective are large and complex haptens are small molecules that are not antigenic by themselves 24 8

9 Lymphocyte Origins Insert figure Lymphocyte Functions T cells (70% - 80%) 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 26 Lymphocyte Functions B cells (20%-30%) differentiate into plasma cells produce antibodies humoral immune response 27 9

10 Comparison of T and B Cells 28 T Cells and the Cellular Immune Response requires antigen-presenting cell requires MHC antigens types of T cells helper T cell-stimulate B cells to produce antibodies CD4 helpter T cells are the target of HIV cytotoxic T cell-attack and destroy cancer cells and virally infected cells memory T cell-provided no-delay response to any future exposure to the same antigen 29 T Cell and B Cell Activation 30 10

11 B Cell Activation, Stimulation and Proliferation 31 B Cell Proliferation and Differentiation 32 Steps in Antibody Production 33 11

12 Antibody Molecules 34 Types of Immunoglobulins 35 Antibody Actions 36 12

13 Immune Responses 37 Classifications of Immunity 38 Allergic Reactions Immune attacks against nonharmful substances that can damage tissues Also called hypersensitivity reaction Allergens-antigens that trigger allergic responses 39 13

14 Allergic Reactions Type I immediate-reaction allergy occurs minutes after contact with allergen hives hay fever asthma eczema gastric disturbances anaphylactic shock 40 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 41 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 42 14

15 Transplantation and Tissue Rejection Transplanted tissues and organs cornea kidney liver pancreas heart bone marrow skin Tissue rejection reaction resembles cellular immune response against antigens important to match MHC antigens immunosuppressive drugs used to prevent rejection 43 Four Major Varieties of Grafts 44 Autoimmunity inability to distinguish self from non-self Make autoantibodies and cytotoxic T cells 45 15

16 SCIDS AIDS Immune deficiencies 46 Life-Span Changes immune system declines early in life when thymus gland shrinks higher risk of infections antibody response to antigens becomes slower IgA and IgG antibodies increase IgM and IgE antibodies decrease 47 Clinical Application Immunity Breakdown: AIDS recurrent fever weakness weight loss caused by HIV (human immunodeficiency virus) HIV impairs macrophages and helper T cells later in infection, HIV impairs cytotoxic T cells HIV mutates quickly immune system cannot keep up with HIV 48 16