0516 - wound healing

Question 1

1. Does an ulcer heal by 1ry or 2ndry intention?

Answer 1

Secondary intention; the edges cannot be opposed and covering skin must grow in
across the bed of granulation tissue.

Question 2

2. If a segment of a liver is donated to a child as a transplant, would the architecture of liver
   ultimately be normal?

Answer 2

Yes the histological picture will have well defined portal triads etc with main bile duct
etc. However, at a macroscopic level, there will not be the usual lobar construction and
the gall bladder will be absent.

Question 3

3. Is cirrhosis of the liver a picture of normal regeneration? (To answer, first what does
   “cirrhosis” mean and then consider what is happening).

Answer 3

No. There are significant amounts of fibrous (connective) tissue separating lobules of
regenerated hepatocytes and biliary tubules. (By definition cirrhosis is liver disease
characterised by loss of normal microscopic lobular architecture). Consider chronic
inflammation.

Question 4

4. In TB of the lung following treatment, is the lung parenchyma normal or abnormal?
   (consider when treated)

Answer 4

No, there has been destruction of tissue and where infection has been present, there will
be significant scarring and fibrosis.

Question 5

5. In TB of lung, as seen on X-ray, what tissue does a Ghon focus represent?

Answer 5

Site of the chronic inflammatory process (caseous necrosis) with subsequent scarring and
calcification.

Question 6

6. Following major surgery, might stiches be left in situ longer in a diabetic patient than
   another patient of the same age?

Answer 6

Yes. Poor tissue healing is common in diabetes mellitus. A combination of altered blood
supply (↓ perfusion) and high blood glucose altering (immune) cell function.

Question 7

what are the 4 principal components of tissue repair

Answer 7

1. cell migration
2. cell proliferation
3. cell differentiation
4. cell-matrix interaction (scaffolding)

Question 8

what determines is the regenerated cell will resemble the original organ?

Answer 8

this only occurs if underlying stroma cell is maintained

degree of differentiation will determine balance between regen and fibroplasia

depends on tissue type as well. connective and mesenchymal cells can proliferate in response to injury. while highly differentiated cells such as CVS can only come from stem cells.

Question 9

describe how fibrosis repairs tissue

Answer 9

1. angiogenesis - via budding and VGEF
2. migration and proliferation of fibroblasts
3. deposition of ECM
4. maturation and remodelling

this most easily seen in the skin but applies else where

Question 10

describe healing by primary intent - clean cut, little damage

Answer 10

1. thrombus clots forms, basal cells start to deposit basal membrane, neutrophils flood in, fibroblasts start to make collagen and ECM (granulation tissue), angiogenesis
2. macrophages present, production of granulation tissue continues, immature scar forms
3. continued fibroblast proliferation, production of collagen + ECM, inflammation fades, remodelling begins

Question 11

describe healing by secondary intent - large tissue damage, which must be filled, original can’t be fully regenerated, function may be lost

Answer 11

e.g. ulcers, infection, infarction

more fibrin and necrotic debris
more intense inflammation
more granulation tissue formed
wound contraction via myofibroblasts which have contractile properties to pull two part together

Question 12

what factors can influence wound healing

Answer 12

nutrition
infection
mechanical factors
individual differences
drugs
radiotherapy
anything that affects inflammatory response

Question 13

what are some examples of abnormal wound healing

Answer 13

keloids - too much granulation replaced by collagen
exuberant granulation

fascitis - rapid growth and proliferation of fibrobalsts and myoblasts