MEDRADSC 1B03 Lecture Notes - Lecture 3: Extracellular Fluid, Frostbite, Semipermeable Membrane
3 Sep 2018
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Non specific: body doesn"t care what the agent is (reacts the same: first line of defence: mechanical barrier (non-specific) Tears & saliva contain enzymes/chemicals that inactivate/destroy potentially damaging material: second line of defence: inflammation & phagocytosis (nonspecific) Neutrophil: is a leukocyte; flood out & go after anything. Macrophages: present if inflammation if let go a little bit longer. Both randomly engulf & destroy bacteria, cell debris, or foreign matter: third line of defence: immune system (specific) Stimulates production of unique antibodies or sensitized lymphocytes following exposure to specific substances. Reacts in a specific way for each kind of inflammatory process. Injury or disease happens if any of the defences fail. Usually all capillaries aren"t open in a particular capillary bed unless the cells" metabolic needs aren"t being met by the blood supply to the area, or an accumulation of wastes occurs. Precapillary sphincters composed of smooth muscle restrict flow; controls fluid exchange between arterioles & venules.
