Lymphatic System & Immunity

Vocab -gen: be produced Humor-: fluid Nod-: knot Immun-: free Inflamm-: set on fire Patho-: disease Lymph: the fluid inside lymph vessels and capillaries

Lymphatic System The lymphatic system: A collection of cells and biochemicals that travel through lymph vessels, organs and glands

Functions Launch immune attacks against foreign particles Protects against toxins and cancer Filters blood plasma

Pathways Begin at capillaries and merge with larger vessels Capillaries → Vessels → lymph nodes → lymph trunks → ducts

Lymph Nodes Lymph nodes: specialized glands that contain lymphocytes B & T cells of the immune system Macrophages that kill microorganisms found all over the body except in the nervous system Functions: Filters harmful particles from lymph Immune surveillance= lymphocytes attack viruses, bacteria and parasites

Lymphatic System Hilum- where blood vessels and nerves join a lymph node Lymphatic trunks: collecting ducts that receives lymph fluid from distal parts of the body

Lymphatic System Lymph Modules: the functioning unit of a lymph node Lymph Sinuses: a network of chambers in a lymph node

Lymph Movement One way Exercise and movement increase lymph flow Breathing stimulates lymph movement Impaired lymph movement: Causes edema (swelling)

Lymphatic System Thymus= a soft gland located posterior to the sternum Large when you are born – shrinks when you get older Secretes lymphocytes and hormones

Spleen The largest organ in the lymphatic system Filled with blood vessels, not lymph Contains lymphocytes and macrophages Filters blood as much as lymph nodes do

Defense Against Infection Pathogen: disease-causing agent virus, bacteria, fungus

Nonspecific (innate responses) Inflammation= swelling, heat, pain, redness and pus Fever= makes body inhospitable to pathogens Phagocytosis= digests foreign material Chemical barriers= body fluid, stomach acid, (low pH) mechanical barriers= skin, mucus membranes, hair, sweat Species resistance= organism can’t survive in human body Natural killer cells= cells that secrete cytolytic (“cell cutting”) substances that cut through cell membranes

Specific Immune Responses Specialized cells recognize foreign invaders Respond more slowly than non-specific responses Antigens= proteins, sugars or lipids on a cell’s surface recognize foreign invaders

Lymphocytes T cells: require antigen-presenting cells to be activated Enter tissues and Kill foreign invaders Have a memory once exposed to a pathogen

Lymphocytes B-cells: activated by specific antigens or T-cells Have a memory once exposed to a pathogen Never enters tissues Produce antibodies

Antibodies Immunoglobins: present in plasma, interstitial fluid, breast milk, tears, bile, stomach acid, nasal mucus, urine Act on allergens, bacteria, viruses, fungus and toxins Reaction to antigens: Tries to contain the pathogen or toxin to the area it is in direct attack, stimulate inflammation, or activate cells to act

Allergic Reactions Allergic reactions: an immune response to a non- harmful substance can damage tissues Allergens: antigens that cause allergic reactions

Allergic Reactions Immediate-reaction allergies: within minutes of contact with allergen Activates B-cells Release histamines and prostaglandins that: Causes blood vessel dilation Swelling Increased mucus production Contraction of bronchial muscles

Transport/Tissue Rejection Transplant/Tissue Rejection: donor part is recognized as an invader and the body reject it Immunosuppressive drugs: used to reduce the chance of tissue rejection Interfere with immune response by suppressing T-cells and antibody formation

Auto Immunity Auto immunity: immune system turning against itself Autoantibodies: attack tissues and organs Examples: type 1 diabetes, mellitus, rheumatoid arthritis, lupus Caused by: Viruses T-cells not “learning” to recognize other threats Genetics

Active Immunity Naturally Acquired: exposure to pathogens stimulates immune response ex: chicken pox Artificially Acquired: a vaccination containing weak or dead pathogens is given to stimulate an immune response ex: polio vaccination

Passive Immunity Naturally Acquired: antibodies passed from mother to fetus through umbilical cord or breast milk Artificially Acquired: antibodies injected into the blood stream