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Lymphatic system and immunity
 

Lymphatic system and immunity

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    Lymphatic system and immunity Lymphatic system and immunity Presentation Transcript

    • Lymphatic system and immunity Closely associated with cardiovascular because it includes a network of vessels
    • Lymphatic vessels
      • Capillaries to larger lymphatic vessels to collecting ducts to subclavian veins in chest
      • Protein molecules that leak out of capillaries are returned to blood via lymph
      • Movement of lymph is controlled by muscular activity; similar to venous flow
    • Lymph nodes
      • Lymph glands – contain many white blood cells; about 2.5 cm, bean shaped
      • Lymph transports bacteria and viruses to lymph nodes where they are attacked
      • Centers for lymphocyte production (a WBC), also made in bone marrow
      • Swell when actively fighting infection or disease; you may feel them in neck, armpit or groin
    • Thymus
      • Soft, bilobed, surrounded by connective tissue
      • Modifies lymphocytes into killer T-cells
      • Secretes thymosin – stimulates maturation of T-cells after they leave the thymus
    • Spleen
      • Largest lymphatic organ
      • Stores blood
      • White pulp is in nodules composed mainly of lymphocytes
      • Red pulp contains RBCs, plus lymphocytes and macrophages
      • Spleen filters blood looking for foreign material which macrophages destroy
    • Tonsils, adenoids
      • Tonsils – in back of throat (laryngopharynx)
      • Adenoids – in nasopharynx
      • Both work in a similar manner to spleen
      • Can swell from chronic infections and block breathing or swallowing – can be removed
    • Nonspecific immunity first line of defense
      • Species resistance – humans are naturally immune to many diseases that affect other species because chemical makeup and body temp are different
      • Mechanical barriers – skin and mucous membranes keep out invaders by being relatively impenetrable as long as they are intact
    • Second line of defense
      • Chemical barriers –
        • acid and pepsin in stomach tear apart microbes,
        • lysozyme in tears is antibacterial
        • Interferons stimulate nearby cells to produce virus blocking proteins
      • Fever – causes iron needed by bacteria to by hidden in liver and spleen, also increases the activity of phagocytes
    • 2 nd line cont.
      • Inflammation – redness, swelling, heat and pain
        • results from blood vessel dilation
        • WBCs are attracted to the site, may form pus
        • Fibrin may form a clot, limits spread of pathogens
      • Phagocytosis – neutrophils and monocytes engulf and digest foreign particles
    • Specific defense (Immunity) third line of defense
      • Antigens – large molecules present in cells
        • Your body recognizes “self” and anything else is foreign.
        • T-cells and B-cells can recognize foreign antigens
      • Cell mediated immunity – T-cells attach to foreign cells and produce chemicals that kill or interfere with cell growth
    •  
    • Immunity cont.
      • Antibody mediated (humoral) immunity – B-cells produce antibodies which react in various ways to destroy specific antigens
      • Memory cells – produced by both T-cells and B-cells
        • Clones of original cells which fought an infection
        • Remain dormant until exposed to any antigen they have previously encountered
        • Produce a rapid response
    • Acquired immunity
      • Active immunity – exposure to a pathogen causes the body to form memory cells – long lasting
        • Naturally acquired active immunity – results from actually having the disease and fighting it off
        • Artificially acquired active immunity – results from vaccines – a weakened or killed form of the pathogen is introduced into the body
    • Acquired immunity cont.
      • Passive immunity – a person receives antibodies produced by another person -short term protection
        • Naturally acquired passive immunity – babies get antibodies from their mothers through the placenta (before birth) and breast milk.
        • Artificially acquired passive immunity – a shot of immunoglobulin (antibodies) that can deactivate a pathogen
    • Allergic reactions
      • Allergies are immune attacks against nonharmful substances
        • Delayed reaction – takes up to 48 hours to show up, usually from repeated chemical exposure
        • Immediate – happen right away, involve histamine and heparin
        • Either could cause anaphylactic shock which can kill
    • Transplantation and tissue rejection
      • The body recognizes a transplant as foreign and attacks it unless the tissue types are extremely similar. Even then, a person may have to take immunosuppressive drugs for life.
    • Autoimmunity diseases
      • The immune system fails to recognize cells as “self” and attacks them
      • Proteins on a pathogen’s cell surface may resemble those on your own cells
      • Examples
        • Type I diabetes
        • Multiple sclerosis
        • Rheumatoid arthritis
        • lupus