TISSUE RESPONSE TO INJURY Tissue Healing

THE HEALING PROCESS Inflammatory Response Phase  (4 days)  Injury to the cell will change the metabolism (cellular function) and initiate an inflammatory response  Signs of inflammation:  REDNESS (rubor)  SWELLING (tumor)  TENDERNESS AND PAIN (dolor)  INCREASE IN TEMPERATURE (calor)  LOSS OF FUNCTION (function laesa)  Leukocytes and Phagocytes (WBCs) will dispose of injury byproducts via PHAGOCYTOSIS

PHAGOCYTOSIS PMNs (Polymophonuclear neutrophils) kill off bacteria (nondiscriminatory) and eventually die off creating a toxic environment Mononuclear phagocytes/Macrophages will remove debris and begin blood coagulation  Exudates form a network of FIBRIN  Epithelial cells migrate along the edges of the wound and FIBROBLASTS enter to regrow cappilaries

INFLAMMATORY RESPONSE

Immediate Vasoconstriction  First 5-10 minutes  The blood vessels will constrict Vascular Dilation  hours  Blood and plasma will flood the area and the tissue will become more PERMIABLE  White blood cells communicate to clean the area of damaged tissues  Clotting will begin

INFLAMMATORY RESPONSE Chemical Mediators  Histamine – helps with vasodilation and increased cell permeability, sensitizes pain receptors  Leukotaxin - Increase cell permeability, allows for the transfer of WBCs through the cell walls  Necrosin – Phagocytic activity  The amount of swelling that occurs will be in direct relation to the amount of damage to the blood vessels Leukocytes will release  Bradykinin – increases cell permeability, increases pain response, stimulates the release of PROSTOGLANDINS  Prostoglandins – increase permeability of blood vessels and surrounding tissues  This increases the amount of space that WBCs have to move

CLOT FORMATION Platelets adhere to form a sticky matrix Protein THROMBOPLASTIN is released from the cells  Causes prothrombin to change to thrombin Thrombin creates fibrin clots that shot off blood supply to the area

THE HEALING PROCESS Fibroblastic Repair Phase  (day 4- week 6)  Scar formation and repair of injured tissues begins immediately after an injury

FIBROBLASTIC REPAIR Revascularization  Growth of new capillaries is stimulated by a lack of O2  Fibroblasts begin laying collagen  This forms a seal over the injured area Wound Contraction  Fibroblasts begin towards the edges of the wound and move towards the center  There is continuous replacement of tissue as the wound heals

THE HEALING PROCESS Maturation/ Remodeling  (Week 6 – 2-3 years)  Realignment or remodeling of the collagen fibers that make up scar tissue  Parallel to the lines of tension  After approximately 3 weeks a NONVASCULAR scar will exist  Wolff’s Law  Bone and soft tissue will respond the physical demands that are placed on them  This leads to remodeling and realignment along the lines of TENSILE FORCE

FACTORS THAT IMPEDE HEALING  The extent of the injury  Edema  Hemorrhage  Poor vascular supply  Separation of tissue  Muscle spasm  Corticosteroids  Keloids  Infection  Humidity/climate  Health, age, nutrition

PAIN Acute Pain last less than 6 months Chronic Pain will last longer Referred Pain occurs away from the actual site of irritation  Myofascial Pain  Trigger points  Sclerotomic Pain  Deep aching pain that is localized and supplied by a single nerve root  Dermatomic Pain  An area of skin supplied by a single nerve root, sharp and localized

QUICK WRITE Why is it necessary to understand the different stages of healing? Write a paragraph on your thoughts and we will discuss this as a class