healing & repair Flashcards
what are the 4 stages of healing in soft tissues
clotting phase
inflammation phase
proliferative phase
maturation phase
what type of repair occurs in hard tissues
fracture repair
regeneration
replacement with functional, differentiated cells
repair
production of a fibrous scar alongside changes in tissue structure/ architecture
labile cells
continuously dividing and regenerating e.g oral keratinocytes of squamous epithelium of the skin
stable cells
low levels of replication, rapid proliferation in response to injury, e.g oral fibroblasts
permanent cells
unable to divide or regenerate e.g neurons
what occurs during the clotting phase (haemostasis) of healing
clot formation via the coagulation system
mitosis of labile and stable cells
what occurs during the inflammation stage of healing
innate immune response - macrophages, nuetrophils phagocytose and degrade infectious agents
stimulation of certain cells e.g keratinocytes to to start regeneration or repair
granulation tissue
new connective tissue with microscopic blood vessels
angiogenesis
formation of new blood vessels
describe how granulation tissue is formed
1st phase - vascular granulation tissue - mix of proliferating capillaries, immune cells and fibroblasts. Capillaries are leaky so fluid and cells can enter the tissue
2nd phase - fibrous granulation tissue - capillaries regress and immune cells return to blood, fibroblasts lay down collagen
describe the process of angiogenesis
new blood vessels are formed from existing vascalature either by sprouting or intussusceptive (splitting). process is driven by VEGF (vascular endothelial growth factor)
what occurs during the proliferative stage of healing
granulation tissue forms, angiogenesis
what is the role of macrophages during the proliferative stage of healing
M2 macrophages are essential in the healing and repair process. They engulf/ degrade pathogens and also produce growth factors e.g VEGF and TGFbeta
what occurs during the maturation stage of healing
granulation tissue is rearranged and collagen fibres are linked
primary intention
tissue regenerates itself, minimal damage
second intention
large infected/ damaged area , larger amount of granulation tissue therefore more scar tissue present
what are the 4 stages of fracture healing
inflammatory stage
repairing stage 1
repairing stage 2
remodelling stage
what occurs during the inflammatory stage of fracture healing
heamatoma formation at fracture (blood clot within tissue)
immune response to clear debris and dying tissue
bone cells deprived of O2/ blood supply die off
occurs within days
what occurs during the 1st repairing stage of fracture healing
occurs within weeks
granulation tissue forms and becomes fibrocartilage callus (soft callus)
osteoblasts produce spongy bone
what occurs during the 2nd repairing stage of fracture healing
occurs within months
remaining granulation tissue is ossified (turned to bone)
formation of hard bone callus
chondrocytes and osteoblasts produce cartilage and bone
what occurs during the remodelling stage of fracture healing
occurs over months/ years depending on severity
angiogenesis
osteoclasts and blasts remodel the hard callus (resorption and formation)
