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 Mononuclear Phagocytes/Macrophages will remove debris and begin blood coagulation Formation of a network of FIBRIN Epithelial cells migrate along the edges of the wound and FIBROBLASTS enter to regrow capillaries

Inflammatory Response

Inflammatory response Immediate Vasoconstriction First 5-10 minutes The blood vessels will constrict Vascular Dilation 24-36 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 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 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 Wound Contraction 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