Stage 1 - Injury

• Definition of Healing

  process by which the body repairs bone, tissue or organ damage caused by injury, infection or disease

  the initial stages of healing r the same in all parts of the body

  
• Bleeding Phase

  bleeding phase = approx 6-8 hrs except complex trauma = 24hrs

  the stage immediately after injury b4 the inflammatory process is activated

  tissue damage, chemical + mechanical changes r seen
• Clotting (1) - Breakdown of Dead Cells & Release of Histamine

  local blood vessels r disrupted casing a cessation in O2 to the cells they perfuse

  these cells die + disintegrate + release enzyme which have a two-fold effect:

  begin to break down the dead cells themselves

  release histamines + kinins which have an effect on both the live cell nearby + the local blood capillary network
• Clotting (2) - Cascade of Reactions

  the disruption of the blood vessels, which caused cell death, also cause local bleeding:

  the RBCs break down leaving cellular debris + free Hb

  thromboplastin (enzyme) that triggers the cascade of reactions resulting in the formation of a blood clot
• Clotting (3) - Role of Thromboplastin -- Fibrin

  thromboplastin w Ca2+ catalyses prothrombin into thrombin, which catalyses fibrinogen into fibrin

  fibrin = meshwork for the clot to form
• Clotting (4) - Role of Serotonin

  serotonin which makes the smooth muscle walls of the blood vessels contract, narrowing + reducing the blood supply to the area

  clot dries out, forming a hard, tough scab that keeps pathogens out

  epidermal cells below the scab start to grow, sealing the wound permanently, while damaged blood vessels regrow
• Clotting (5) - Role of Collagen Fibres

  collagen fibres r deposited to give the new tissue strength

  once the new epidermis reaches norm thickness, the scab sloghs off + the wound is healed
• Factors that Determine the Bleeding Process

  these changes r affected by age n- intramuscular bleeding is more profusing if over 30 yrs

  the amount of bleeding that occurs will be partially dependent on the vascularity of the tissue involved

  a fitter individual is likely to have muscle tissue which is more highly vascular + therefore greater bleeding will occur w muscle injury

  if an individual cont to exercise once injured the bleeding will be more extensive due to the high blood flow during exercise