Healing and Repair Flashcards
What is regeneration/resolution vs Fibrous repair/organisation?
Regeneration is growth of cells to replace lost ones - requires connective tissue scaffold to not be lost
Fibrous repair is fibrovascular connective tissue growing into area of tissue loss (significant or complex tissue lost)
What three processes does wound healing involve?
Haemostats
Inflammation
Regeneration
What is primary vs secondary intention healing?
Primary is regeneration
Secondary is fibrous repair
Which type of repair to labile, stable and permanent cells undergo?
Labile/Stable - Regeneration
Permanent - Fibrous repair
How do stem cells replicate?
Asymmetrically - produce one ‘self’ cell and one differentiated cell
What is a labile tissue? Give example
Proliferate through life - mitosis
E.g. skin epithelia, columnar epithelium of GI and uterus, transitional epithelia of GI, cells of bone marrow and haemopoeitic tissues
What is a stable tissue? Give examples
Quiescent but can undergo proliferation if needed
e.g. parenchymal cells of liver, kidneys, pancreas, SMCs, vascular endothelial cells, resting lymphocytes and other WBCs mesenchymal cells e.g.: osteoclasts, fibroblasts
What is a permanent tissue? Give examples?
Contain cells that have left the cell cycle and cannot undergo mitosis
e.g. neurones, cardiac myocytes, skeletal muscle cells.
What is required for cells that are terminally differentiated to be able to regenerate? What if they can’t regenerate?
Stem cells
Otherwise will undergo secondary intention healing
What are the 4 stages of fibrous repair post inflammation?
1) Phagocytosis of debris
2) Proliferation of endothelial cells - angiogenesis - granulation tissue
3) Fibroblasts and myofibroblasts secrete collagen & wound contraction
4) Matures into scar - less vascularisation and contracts
Which cells are unipotent multipotent totipotent?
Uni - produce 1 cell line e.g. epithelia
Multi - produce many e.g. haematopoeitic
Toti - embyonic
Why is a scar white and hairless? Why do they stretch?
Often no regeneration of melanin or hair follicles etc
Stretch as they produce collagen but not elastin so don’t recoil with growth e.g.
Which three ways can cells communicate in regeneration and repair? Which is the most important?
Endocrine - hormones
Paracrine - local mediators e.g. growth factors
Autocrine - cell to cell contact or cell-connective tissue contact
What are growth factors? Which 4 major growth factors are important in wound healing?
They are ‘local hormones’ polypeptide protooncogenes that bind to cell surface receptors and stimulate transcription of genes that promote mitosis
1) EGF
2) PDGF
3) VEGF
4) TNF
Name three cells involved in wound healing that produce growth factors
Macrophages
Platelets
Endothelial cell