healing ad repair Flashcards
what is regeneration?
proliferation of cells and tissue to replace lost or damaged cells and tissue - normal structure restored
what is repair?
response to injury involving regeneration and scar formation (fibrosis), normal structure permanently altered
which outcome is seen as resolution, regeneration or repair ?
regeneration
what are liable cells?
normal state is active cell division, rapid regeneration
give an example of a liable cell?
oral keratinocyte
what is a stable cell?
not normally dividing at significant rate, can undergo rapid proliferation in response to injury
give an example of a stable cell?
oral fibroblast
what is a permanent cell?
unable to divide or regenerate
give an example of a permeant cell
nerve cell
what are the 4 stages of wound healing?
1 haemostasis
2 inflammatory
3 proliferation
4 remodelling
what does haemostasis refer to?
blood clotting
what happens during the inflammatory phase of wound healing?
fibroblasts and macrophages accumulate, scab forms
what happens during the proliferation phase of wound healing?
1st phase - vascular granulation tissue forms
2nd phase - fibrous granulation tissue forms
what happens during the remodelling phase of wound healing?
freshly healed epidermis and dermis, re-epithelialisastion and maturation
what fibrous protein pulls the wound together and provides tensile strength?
collagen
what does healing by 1st intention refer to?
surgical incision
what does healing by 2nd intention refer to?
dirty wound, larger scab, more inflammation due to necrotic debris, exudate and fibrin to remove, larger granulation tissue, invoke wound contraction
what is angiogenesis ?
growth of new BVs from existing vasculature
what are the 2 mechanisms of angiogenesis and how do they work?
- sprouting ( new BV from existing)
- intussusceptive ( splitting angiogenesis)
what is angiogenesis controlled by?
vascular endothelial growth factor (VEGF)
which two growth factors inhibit and promote cell growth and differentiation?
- cytokines
- hormones
give some functions of growth factors
- promote cell survival
- locomotion
- contractility
- differentiation
- angiogenesis
- activate signal transduction pathways
which cells produce collagen?
fibroblasts
what are the 4 stages of fracture healing?
- reactive phase
- reparative (regenerative) phase
- bonny callous formation
- remodelling phase
what happens during the reactive phase of fracture healing?
- blood clot forms (haematoma)
- macrophages scavenge debris producing inflammatory agents
what happens during the reparative phase of fracture healing?
- inflammation triggers growth of new BVs
- chondrocytes secrete collagen and osteoblasts start producing spongy bone
- soft callus is formed
what happens during the bonny callous phase of fracture healing?
- woven bone replaces soft callous to create hard callous round the broken bone fragments
what is fibrosis?
formation of scar tissue- extensive deposition of collagen & formation of excess fibrous connective tissue
fibrosis occurs in response to what?
chronic inflammation
which immune cells initiate fibrosis and which growth factor do they produce?
M2 macrophages - releasing TGF-beta
during which phase of fracture healing is fracture callus produced?
regenerative
granulation tissue formation occurs during which stage of wound healing?
proliferation
fibrosis is characterised by the extensive deposition of which substance in tissues?
collagen
what happens during the remodelling phase of fracture healing?
- osteoclasts and osteoblasts remodel the bone, replacing hard callus with mature lamellar bone
during which stage of wound healing does angiogenesis occur?
proliferative phase
