Healing and Repair Flashcards
What is healing?
Physiological response to tissue response to tissue damage
What are the two main causes of tissue damage?
- Wound
- Inflammatory process in internal organ
What are the two steps to healing and repair?
- Regeneration
- Scar formation
What is regeneration in healing?
Growth of cells and tissues to replace lost structures
What is scar formation in healing?
Laying down of fibrous tissue
What does the result of healing depend on? (4)
- Damage nature
- Damage severity
- Damage duration (acute/chronic)
- Tissue type involved
What are the two types of cell renewal?
- Proliferation
- Differentiation
What does proliferation do in cell renewal?
Replace lost cells
What does differentiation do in cell renewal?
Replace complex architectural structures
What are the 3 types of cell according to proliferation ability?
- Labile cells
- Stable cells
- Permanent cells
What is the proliferation ability of labile cells?
Good capacity to proliferate
What is the proliferation ability of stable cells?
Slow proliferative rate unless necessary, specific stimulus increases rate
What is the proliferation ability of permenant cells?
No effective regeneration
Give an example of a labile cell
Skin basal cell
Why do skin basal cells have a high proliferation rate?
Increased mitotic activity, always building up to replace loss
Give an example of a stable cell
Hepatocytes
In what situation can stable cells regenerate quickly?
Post trauma
What are the consequences of myocardium being permanent cells post MI?
- Old MI healed
- Not replaced with new myocardium just with fibrotic tissue
- No contractile ability
- Less resistant to mechanic pressure
- Can expand cause aneurysm after MI
What can fibrotic plaques in the heart cause?
Arythmia - alters specific heart area contraction ability because can’t transmit stimulus
What is liver cirrhosis made up of in terms of healing?
Fibrosis with proliferation and regeneration of hepatocytes
What are the properties of the liver in liver cirrhosis? (6)
- Micronodularity
- V uneven surface
- Hard to touch
- Fibrosis between nodules
- Decreased in size
- Palpable
What can be seen histologically in liver cirrhosis?
Regenerative nodule of hepatocytes surrounded by strands of fibrous tissue
How does fibrosis affect labile and stable cell population?
Damage of both parenchymal and stromal cells
What are parenchymal cells?
Functional cells of an organ in the body
What are stromal cells?
Structural tissue of organs - connective tissues
How does fibrosis affect the permanent cell population?
Damage to non regenerating cells
What are the 3 parts to fibrosis?
- Formation of granulation tissue
- Extracellular matrix protein deposition
- Remodelling
What is granulation tissue later replaced by in fibrosis?
Fibrous tissue
What extracellular matrix proteins are deposited in fibrosis?
- Collagens
- Fibronectin
What deposits extracellular matrix proteins in fibrosis?
Fibroblasts
What occurs in remodelling in fibrosis?
Maturation and organisation of fibrous tissue
