how body responds to injury - healing Flashcards
What happens after inflammation?
- resolution
- regeneration or repair
What is complete restoration of the tissue to its normal state called?
restitutio ad integrum
What do macrophages do?
- clear offending stimuli and dead tissue
- produce growth factors for healing response
What actions can macrophages perform (like for themselves)?
- chemotaxis
- hypertrophy
- pseudopodia
- pinocytosis
- phagocytosis
What is pseupodia?
active movement (makes an arm basically)
What is pinocytosis?
ingest fluid from their surroundings
What can labile and stabile cells heal by?
regeneration or repair
What can permanent cells heal by?
Repair
What is regeneration dependent on?
preserved integrity of extracellular matrix (scaffolding) or basement membrane
Under what condition can liver tissue regenerate from stem cells?
if the stromal reticulin scaffolding remains intact
What are the steps to repair?
- formation of granulation tissue
- formation of connective tissue/scar
What controls the development of new blood vessels?
vascular endothelial growth factor (VEGF-A)
What are the steps to angiogenesis?
- vasodilation
- degradation of BM of local blood vessels
- migration of endothelial cells and recruitment of endothelial precursor cells from bone marrow
- maturation of endothelial cells into tubes
What are the two parts to formation of granulation tissue?
angiogenesis and the proliferation of fibroblasts
What growth factors do macrophages release to induce proliferation of fibroblasts?
fibroblast growth factors (FGFs)
What do fibroblasts produce?
ECM proteins (mainly collagen and elastin)
What controls the production of ECM proteins by fibroblasts?
transforming growth factor beta (TGF-beta)
What does granulation tissue eventually become?
a scar
What determines the remodelling of scars?
interactions of collagen deposition and degradation by matrix metalloproteinases (MMPs)
What are the steps to scar remodelling?
- collagen changes to type 1 collagen
- blood vessels disappear
- contraction of scar tissue
- final scar is collagen and remaining fibroblasts
What percentage of normal tissue strength do scars retain?
80%
