healing and repair Flashcards
What will contribute to resolution rather than repair?
- initiating factor removed
2. tissue undamaged/able to regenerate
What will lead to repair rather than resolution?
- initiating factor still present
2. tissue damaged and unable to regenerate
What are the features of repair?
- replacement of damaged tissue by fibrous tissue
2. the collagen is produced by fibroblasts
Give examples of repair
- heart after myocardial infarction
- brain after cerebral infarction
- spinal cord after trauma
Which cells can regenerate?
hepatocytes pneumocytes all blood cells gut epithelium skin epithelium osteocytes
Which cells do not regenerate?
cardiac myocytes
neurones
(striated muscle cells)
What two pt populations suffer with poor wound healing?
elderly
diabetics
What is healing?
restoration with no/minimal residual defect:
- superficial skin abrasion
- healing by 1st intention
Is healing by second intention classified as healing or repair?
repair
Describe healing from skin abrasion
- cells proliferate and spread out as a thin sheet until the defect is covered
- stimulus to proliferate is switched off by contact inhibition
- epidermis is rebuilt from the base upwards
the scale is a layer of fibrin that protects the epidermis as it grows
cells from sweat glands and hair follicles can contribute to healing
What is organisation?
repair of specialised tissues by the formation of a fibrous scar
What happens in organisation?
- granulation tissue is formed and then contracts and accumulates collagen to form a scar
- dead tissue is removed by phagocytosis
what is granulation tissue made of and how is it formed?
capillary loops and myofibroblasts
capillary endothelial cells proliferate and grow into the area
fibroblasts divide and secrete collagen and ECM
collagen forms a scar
why does a wound contract?
Contraction of myofibroblasts in granulation tissue to reduce the volume tissue for repair
What is a disadvantage of granulation tissue?
contraction of scar tissue around a lumen causes stenosis/stricture and contracture in muscles