Friday, November 11, 2016

ch. 12 | the lymphatic system & immunity

  • functions:
  1. drainage- interstitial fluid is carried through the system & empties into the veins, where it becomes part of the blood plasma again
  2. transport- moves lipids & lipid-soluble vitamins from digestive tract to blood 
  3. immunity- lymphocytes fight foreign cells 
  • lymph: when interstitial fluid enters lymphatic vessels; drained by lymphatic or thoracic duct 
  • primary lymphatic organs: (sites where stem cells divide & develop into B & T cells)
-red bone marrow
  • T-cells= T lymphocytes (made in red bone marrow & matures in thymus)
  • B-cells = B lymphocytes (made & mature in red bone marrow)
  • secondary lymphatic organs: (sites where most immune responses occur)
-spleen: largest lymphatic organ
  • pathogens: disease-causing organisms
immunity: ability to protect against disease 
  • innate immunity: series of non-specific physical & chemical defenses 
-physical barriers: skin, mucous membranes in the nose, upper respiratory tract, intestines, reproductive & urinary systems
-chemical barriers: chemicals w/in various fluids & secretions, killer cells, inflammation, & fever can slow growth of microbes

  • adaptive immunity: ability to adapt to specific types of infections or antigens
  • cell-mediated immunity: effective against INTRAcellular pathogens, involves T-cells, always involves cells attacking cells 
  • antibody-mediated immunity: effective against EXTRAcellular pathogens, involves B-cells
-cell-mediated & antibody-mediated immunity often work together to rid the body of antigens
  • active immunity: exposed to antigens & body develops antibodies in response; stays for longer periods bc memory cells
  • passive immunity: received pre-made antibodies that body can use to defend itself; fleeting
  • autoimmunity: immunological response against a person's own tissues (immune cells attack your own body cells)
immune response time speeds up after the initial exposure 
-initial response to infection may take several days or weeks
-clonal selection process produces memory cells 
-subsequent exposure to the same antigens--> secondary immune response which is stronger
  • vaccination: receipt of a vaccine (consists of weakened pathogens)
  • acquired immunodeficiency syndrome (AIDS): condition in which a person experiences many infections due to progressive destruction of cells of lymphatic system
  • human immunodeficiency virus (HIV): virus that causes AIDS
-it is not easy to get infected w it 
-cannot be exchanged through casual contact- usually through exchange of body fluids
-symptoms progress SLOWLY & progress in severity 
-is a retrovirus (a virus that can convert its RNA into DNA)

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