Lymphatic & Immune Systems

Lymphatic pathways & capillaries

Lymphatic trunks and ducts Asymmetrical!

Edema 24 liters of lymph are pushed from capillaries every day to bathe the cells – if it isn’t all collected – it’s edema!! Post-mastectomy lymphedema >

What is lymph? It is plasma It is interstitial fluid It is fluid picked up by lymph capillaries It depends where it is!!

What does lymph do? Collects fluid and proteins that squeeze out through the capillaries Absorbs dietary fats Transports bacteria and viruses to lymph nodes

Keep it moving No heart Skeletal muscle movement Valves prevent backflow Trunks contract a little Inhaling creates pressure that moves lymph from abdominal to thoracic cavity

Lymph nodes Bean shaped 2.5 cm long Medulla has T cells and macrophages One exit slows traffic

Lymphoid organs Do NOT filter lymph, but play a role – Tonsils (MALT) – Peyer’s patches (MALT) – Thymus gland – Spleen MALT = mucosa-associated lymphatic tissue

Spleen & Thymus Spleen – filters blood – White pulp contains lymphocytes – Red pulp filters out broken down RBC’s Thymus – contains lymphocytes that mature in T lymphocytes

2 Lines of Defense Innate – Species resistance – Mechanical barriers – Chemical barriers Tears Stomach acid Salt Antimicrobials – Fever – Natural Killer Cells – Inflammation – Phagocytosis Adaptive – Antingens (sprinkles) – Antigen-presenting cells – T cells – Cytotoxic T cells ( fight cancer ) – Memory T cells – Helper T cells ( stimulate B cells ) – B cells Immunoglobins = antibodies

What’s the diff? T cells Directly attack cells w/ toxins or growth inhibitor Mature in the thymus gland Activated by antigen-presenting cells Helper T cells are targeted by HIV Cytotoxic T cells target tumors and virus infected cells Memory T cells confer immunity Activate B cells B cells Differentiate into Plasma cells that produce antibodies Activated by specific antigens or helper T cells Mature in the bone marrow Part of the humoral response

What’s the same? Both respond to specific antigens We have millions of varieties of each

What do antibodies do? Attack – Disable them so that macrophages will get them Activate enzymes that attack antigens – Complement proteins Change the environment to stop the antigens – inflammation

Tissue Rejection Human Leukocyte Antigens (HLA’s) determine our tissue type Inherited from parents Three groups: HLA-A,HLA-B and HLA-DR. many different specific HLA proteins within each of these three groups. ¼ chance that you and a sibling are identical t/html/hla.html

Allergic (hypersensitivity) Reaction Type I (anaphylactic) – Triggered by allergens – Occurs within minutes – Overproduction of IgE antibodies – Severe inflammation Ex: peanut allergy Type IV ( delayed-reaction ) – Repeated exposures to allergins – Activates T cells – T cells cause inflammation Ex: poison oak

Autoimmunity Cytotoxic T cells attack tissues of your own body Mistaken identity Why? – Improperly educated T cells? – Virus with “self markers” on it? Examples: rheumatoid arthritis and multiple sclerosis