Tissue healing Flashcards
what are the 2 classifications of healing?
primary and secondary intention
what is primary intention?
minor wounds and surgical incisions with the use of sutures
bring 2 parts of the injury together and let them heal
what is secondary intention?
more severe wounds
requires growth b/w the 2 ends of a wound
what are the 4 phases of healing?
- hematosis and degeneration
- inflammation
- proliferation and migration
- remodeling and maturation
what is the hematosis phase of healing?
the process of stopping blood flow through the locally damaged vessels into the injury site via coagulation-bleeding has to stop or healing doesn’t progress
shortest healing phase
vasoconstriction f/b vasodilation
degeneration is the formation of hematoma, necrosis of dead cells, and start of inflammatory cell response
what is the shortest healing phase?
hematosis
what is the inflammation phase of healing?
function: to inactivate the injurious agent, break down and remove dead cells, and initiate healing
typically 1-3 days and sometimes up to 10 days
goal: to replace damaged tissue with healthy regenerated tissue, a fibrous scar, or both
debris removal 5-6 hours post injury and continues for the next 24-48 hours
what are cell aggregation centers?
areas of whitish pus
what does yellow pus mean?
infection
what are the signs of inflammation?
redness, edema, pain, increased temp, and loss of normal function
what causes redness?
histamine and other hormone and chemicals released
what causes edema?
leakage of fluid, cells, and chemicals
what causes pain?
histamine, prostaglandin, and bradykinin release cause hypersensitive and irritable nerve endings
pressure from edema on nerve endings
what causes increased temperature?
increased local cell and chemical activity
what is an important role of inflammation?
may function to immobilize injured areas
what is the proliferation phase of healing?
the phase that begins with debridement to angiogenesis (production of blood vessels)
-newly formed vessels are leaky giving tissue its edematous appearance
about 5 days following injury to around day 21
fills gaps in tissue
increase in fibroblasts and decrease in PMNs
tissue becomes more dense and protective
increase in extracellular collagen that replaces the ECM
increased proteoglycans
2-4 weeks long
growth factors: andothelial production, angiogenesis, and fibroblasts
what is the role of fibroblasts?
largely responsible for angiogenesis at about 3-5 days post injury
what is early proliferation?
type 3 collagen about 24-48 hours post injury
type 3 is first laid down in injured tissue (weak and thin) to provide early tensile strength
replaced by type 1 collagen by about day 14 to increase cross link formation
what is collagenase?
released during epithelialization to prevent overproduction in collagen (too much scar tissue would prevent mobility and lead to Keloid scar formation)
what are external signs of proliferation?
redness and swelling due to increased capillaries and extra water volume
pain due to pressure sensitive nerve endings (pain with palpation) and stretch sensitive nerve endings (pain with stretch)
what is the remodeling phase of healing?
scar tissue is reduced and remodeled
collagen transition with type 3 being replaced by type 1
thicker and reorient in response to stress applied
wound sensitivity lessens
more parallel fibers and tendons while ligaments have slight deviations bc they absorb stress in multiple planes
about 12 months or long
myofibroblasts are responsible for wound contraction
immature collagen has hydrogen bonds then progresses to covalent bonds to be stronger
at 14 weeks tissue is unresponsive to remodeling
what is a contracture of tissue?
excessive shrinkage of tissue near a joint that limits mobility
what is arthrofibrosis?
local or global periarticular scarring (around a joint) from surgery or trauma
thickened fibrotic capsule that inhibits motion
causes: prolonged immobilization, infection, or graft malposition post reconstruction
is skeletal muscle fiber able to regenerate?
yes, as long as the basement membrane remains in tact
result from mitotic division of satellite cells to promote healing
sprain
ligament
strain
tendon or muscle
is scar tissue contractile or non contractile?
non contractile so when in a muscle it reduces mobility
what happens if there is no basement membrane?
the satellite cells have no place to set up and multiply
muscle tissue heal via connective scar tissue and increases risk of reinjury
