4. Healing Flashcards
labile cells
cells that multiply constantly throughout life
stable celsl
cells that multiply when needed
permanent cells
incapable of multiplication - cannot regenerate
brain cells and skeletal and heart muscles
resolution
disappearance of a symptom or condition
wound contraction
myofibroblasts decrease the size of the wound. grips wound edges and contracts. when cells roles are close to complete, unneeded cells undergo apoptosis
wound contracture
excess wound contraction, leads to physical deformities characterized by skin constriction and functional limitations
healing by primary intention
when wound edges are sutured/glued together so that they are adjacent to each other. minimal scarring
healing by secondary intention
allowance of wound granulation –> broader scar, therefore healing process can be slow due to presence of drainage from infection
adhesion
scar tissue in body cavities that joint issues or organs together that normally are not connected
granulation tissue
new connective tissue and tiny blood vessels that form on the surfaces of a wound during healing
keloid formation
scar formation that is composed of collagen (either type III [early] or type I [late]), result of overgrowth in granulation tissue (type III) at the site of healed skin injury –> slowly replaced by type I
what can cause delay in wound healing? (5)
1 reduced blood supply 2 infection 3 foreign bodies 4 excessive movement 5 location of injury
skin healing (3 steps)
- inflammatory phase
- proliferative phase
- repair and remodelling phase
explain what happens in the inflammatory phase
bleeding leads to fibrin formation, resulting fibrin is semi-permanent and also acts to stop bleeding (clot)
explain what happens in the proliferative phase (dermis and epidermis as well)
lots of growth factors released from the clot causing increased cell division
dermis: cell division of fibroblasts and endothelial cells
epidermis: cell division results in re-epithelialisation
explain what happens in the repair and remodelling phase
emigration/chemotaxis of fibroblasts and endothelial cells, fibroblasts form collagen, angiogenesis
forms new tissue called GRANULATION TISSUE
maturation process of granulation tissue
- gap is closed between endothelial cells of blood vessels
- fibroblasts transform into myofibroblasts to produce wound contraction
- type I collagen progressively replaces type III collagen
how does wound contraction work?
fibroblasts transform into myofibroblasts, the smooth muscle like cells link together and contract to produce tension in the wound which is necessary for type I collagen to form (initially there is no tension in the wound, which is why we only see type III/immature collagen formation)
wound healing - granulation to scar tissue (3)
- blanching (apoptosis of endothelial cells)
- tensile strength increases (leading to decreased ability to pull wound apart)
- wound contracture (late process of remodelling which causes shortening of collagen fibers in the scar. this can be detrimental, reducing function or even causing death)
