Pathoma - Ch. 3 - Wound Healing Flashcards
what are the two key components of healing?
a combination of regeneration and repair
what type of tissue do you replace damaged tissue with in regeneration?
- native tissue
- it is dependent of regenerative capacity of the tissue itself
tissues are divided into three types based on regenarative capacity. what are the 3 types?
1) labile tissues
2) stable tissues
3) permanent tissues
what are labile tissues?
tissues that constantly cycle to regenerate tissue via stem cells
egs: SI, LI, skin, bone marrow
where are the stem cells located for the small/large bowel, skin and bone marrow?
SB/LB: mucosal crypts
skin: basal layer
bone marrow: hematopoietic stem cell (CD34+)
what are stable tissues?
quiescent cells, but can reenter cell cylce
eg: regeneration o fthe liver by compensatory hyperplasia after partial resection
what are permanent tissues?
tissues that lack significant regenerative potential
myocardium
skeletal muscle
neurons
what happens to the permanent tissues when they get damaged and need to be fixed?
they get repaired instead
what does repair do?
replaces damaged tissue with fibrous scar
- when regenerative stem cells are lost or when tissue lacks regenerative capacity
what is the initial phase of repair?
granulation tissue
what does granulation tissue consist of?
fibroblasts (deposit type III collagen)
capillaries (provide nutrients)
myofibroblasts (contract wound)
what does granulation tissue eventually form, and how?
everntually results in scar formation
- type III collagen is replaced with type I collagen
- collagenase removes type III collagen and requires zinc as a cofactor
what is the mechanism of regeneration and repair?
it is mediated by paracrine signaling via growth factors
- interaction of factors with receptors results in gene expression and cellular growth
whats TGF-alpha do?
epithelial and fibroblast growth factor
whats TGF-beta do?
important fibroblast growth factor; inhibits inflammation
