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Flashcards in Repair and regeneration Deck (65)
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how is healing divided?

repair and regeneration


what is the body's main response to injury?

acute inflammation


what is the main role of acute inflammation?

to allow the immune system into the damaged area, clear away dead tissue and to protect against local infection


what is the ideal outcome?

resolution - when organised tissue replaces the damaged area with identical tissues in structure and function to the original - cell must be able to regrow and cell debris must be cleared


what happens if the damage is very severe?

the damaged cells cannot regrow and the architecture of the tissue is destroyed meaning that healing takes place by formation of a scar - fibrous repair


what is the basis of regeneration?

normal structure and function is preserved


what are the three things that result from acute inflammation?

repair, regeneration or chronic inflammation


what are the two most important factors in determining the outcome of the injury?

the ability of the cells to replicate and the ability of the cells to rebuild complex architectural structures


which cells will continuously go through the cell cycle?

cells of skin and GIT - those that need to be continually replaced due to exposure - labile cells


What are permanent cells and quiescent cells?

permanent have no chance of replication such as neurons and quiescent have a very slow rate of replication but can speed up when required such as liver


what happens in S phase and G2 to M phase?

in S phase there is chromosomal replication and between G2 and M there is the check for damaged or unduplicated DNA


what happens in G1 and between G1 and S?

in G1 there is centrosome duplication and between G1 and S there is check for DNA damage


what are the characteristics of a labile cell population?

active stem cell population, excellent regenerative capacity and high normal turnover rate


where is the active stem cell population found in epidermis?

in a particular part of the body of the epidermis at the basal layer


what are the characteristics of the stable/quiescent cell population?

good regenerative capacity, low physiological turnover rate but it can greatly increase if needed


what are the characteristics of permanent?

they have no regenerative capacity, are long life cells and have no physiological turnover


what are the characteristics of stem cells?

prolonged self renewal and asymmetric replication


what happens in the mitosis of stem cells?

one of the daughter cells will retain the characteristics of the stem cell but the others will progress along the differentiation pathway


what happens before stem cells reach the epidermis?

there is terminal differentiation


what is essential for regeneration to occur?

no severe local damage, complex architectural structures not damaged and connective tissue framework still present


what is cirrhosis?

it is the collapse of the reticulin - the normal architectural framework in the liver and therefore it cannot regenerate - usually occurs by persistent long term exposure to noxious agents - regenerative nodules are separated by a fibrous septum - imbalance between the hepatocyte regeneration and failure to reconstruct the architecture


what happens in regeneration when a labile cell population is lost?

it can be restored - cells at the edge of the defect can multiply to cover the defect - one they cover the defect proliferation stops - contact inhibition - epidermis grows from the base upwards


what is regeneration controlled by?

growth factors, cell to cell and cell to matrix interactions


what happens in repair?

healing by non-specialised fibrous tissue resulting in functional consequences


what is the difference between mechanical and electrical heart damage due to fibrous scar tissues?

mechanical: loss of pumping capacity
electrical: focus of the abnormal electrical activity resulting in arrhythmia or disruption to the cardiac conducting system giving heart block


what is organisation?

the repair of specialised tissue by formation of a fibrous scar - basic stereotyped pathological process


what occurs in organisation?

the production of granulation tissue on a scaffold of fibrin and then removal of dead tissue by phagocytosis


what is granulation tissue?

it is from endothelial cell proliferation and it is tissue with capillaries within it - important for inflammation and has white cells for phagocytosis of dead matter


what is responsible for contraction in wounds?

myofibroblasts - synthesis ECM and collagen and infiltrate the granulation tissue - acquire myofibrils - they have contractile capacity - found in granulation tissue


what is wound contraction important for?

reducing the volume of tissue for repair (up to 80%)