Regeneration of injured cells by cells of same type, for example regeneration of skin/oral mucosa...
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Transcript of Regeneration of injured cells by cells of same type, for example regeneration of skin/oral mucosa...
Tissue Repair
Regeneration of injured cells by cells of same type, for example regeneration of skin/oral mucosa
Replacement by fibrous tissue (fibroplasia, scar formation)
Both require cell growth, differentiation, and cell-matrix interaction
Varieties of Proliferative Potential
Stable (quiescent) cells:◦Normally little proliferation but remain
capable of more rapid cell division following injury.
◦Liver, kidney, pancreas, endothelium, fibroblasts
◦Chances of regeneration are GOOD
Varieties of Proliferative Potential
Labile (always dividing) cells: ◦Replace dying cells◦Epithelial cells of the skin, oral cavity,
exocrine ducts, and GI tract; endometrial and bone marrow cells.
◦Chances of regeneration are EXCELLENT
Varieties of Proliferative Potential
Permanent (non-dividing ) cells:◦Not capable of proliferation.◦Irreversible injury leads only to scar◦Nerve cells, myocardium, skeletal
muscle,
Cell Cycle
Cell Signaling PatternsAutocrine = ligand is secreted and
detected by same cell
Paracrine = ligand is secreted and separately detected by neighboring cells
Endocrine = ligands (usually hormones) are secreted into the vasculature to affect distant target cells
Wound healing
Healing by first intension (primary)This occurs in clean, incised
wound with good apposition of the edges.
24 hours
3 to 7 days
WEEKs
Healing by second intension(secondary)
This occurs in open wound, particularly when there has been significant loss of tissue , necrosis or infection
24 hours
3 to 7 days
WEEKs
FIBROSISFibrosis, in general, refers to any
fibroblast proliferation with deposition of excess extracellular matrix which is mostly collagen.
Leads to functional loss.It is the end result of wound
healing
This is a healing biopsy site on the skin seen a week following the excision, The skin surface has re-epithelialized, and below this is granulation tissue with small capillaries and fibroblasts forming collagen.
Complications of Wounds
• Deficient scar formation – wound dehiscence/ ulceration
• Excess repair – keloid formation
• Excess contraction – joint contractures/ intra-abdominal adhesions