Flashcards in Repair and regeneration Deck (65)
how is healing divided?
repair and regeneration
what is the body's main response to injury?
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