Repair and Regen Flashcards
what happens upon cell injury
acute inflammation = immune system enters damaged area to clear dead tissue and protect against infection
what is regeneration vs repair
regen - cells regrow and tissue becomes identical in structure from before
repair - excessive or prolonged injury - cell architecture destroyed and tissue can’t regenerate but healing forms scar tissue (can lead to loss of function)
what does regen and repair depend on
ability of the cells to replicate ability to rebuild architectural structures
what are the three types of cells types differentiated by their regenerative ability
labile - excellent regen - rapid turnover (epithelia of skin or gut)
stable (quiescent) - no turnover unless needed (liver / renal tubes)
permanent - no turnover or regen capacity (neurones, striated muscle cells)
where to replaced cells come from in labile and stable ells populations
stem cell pools
what must be preserved for regeneration to occur - give an example of a disease that destroy this
architecture of the cell (connective cell framework)
cirrhosis destroy reticulin framework - no regen
what is the mechanism of regeneration
complete restitution
damaged area - cells replicate to form protective layer - replication stops (contact inhibition) once covered epidermis is revolt from base upwards
what is the mechanism of repair
formation of fibrous scar which starts as granulation tissue
made up of capillary loops, phagocytic cells, my-fibroblasts (release firkin scaffold)
this granulation tissue contracts to form firm scar
what is dangerous about scar tissue formation
burns - toughening of skin =- restricted movement
oesophageal scars - narrowing, dysphagia
tissue becomes less vascular and more collagenous
what are the two steps of skin healing
first intention
second intention
describe first intention of skin healing
if margins are close or stained together, helloing = first intention (must be clean and have blood supply)
epidermis is regenerated and forms scab, from bottom up
implantation dermoid (mainly larger wounds) - proliferated cells close wound and migrate to dermis forming keratin filled cyst
describe second intention of wound healing
margins aren’t close - infected wound - foreigns bodies present
epidermis is repaired, granulation tissue forms and scar
what is a keloid scar
excessive fibroblasts and collagen proliferation
what factor inhibit healing
local - infection, blood supply, mechanical stress
systemic - age, drugs, anaemia, malnutrition, diabetes, vit C deficiency
describe what happens during bone fracture healing
haematoma forms at fracture site and provides scaffolding framework
phagocytes enter and destroy necrotic fragments of bone
osteoblasts produce callus which is remodelled into hard lamellar bone
