Lecture 7 - Regeneration And Repair Flashcards
What is repair?
(Fibrosis)
When tissue has been substantially damaged leading to repair with connective tissue
What are the general stages of wound healing?
Injury occurs
Haemostasis (blood clot when blood vessels damaged)
Inflammation
Then either Regeneration and/or repair
What is regeneration?
Re growth of cells with minimal evidence of injury (cant tell injury has happened)
What type of injuries can be regenerated?
Minor injuries (skin incision/abrasion)
What area the 3 criteria for regeneration to happen?
1.) Injury must be minor (skin abrasion/incision)
2.) Connective tissue architecture must be intact
3.) Tissue must have ability of regeneration
What is an example of physiological regeneration (normal)?
Haematopoiesis
(Production of blood cells from bone marrow)
What type of cells do new cells come from?
Stem cells
What are the features of stem cells?
Differentiation
Self-renewal
What is meant by potency of a stem cell?
The ability of the stem cell to differentiate into different types of cell
What is a Totipotent stem cell?
Where can they be found?
Can differentiate into all cell types
Embryonic stem cells
What is a Multipotent stem cell?
Where can they be found?
Can differentiate into several cell types but NOT ALL
Haematopoietic stem cells (Bone marrow)
What is a Unipotent stem cell?
Where can they be found?
Can only differentiate into ONE cell type
Epithelial stem cells (only into epithelium)
What are the 3 categories of tissue when referring to their ability to regenerate?
Labile Tissue
Stable Tissue
Permanent Tissue
What is the regenerative ability of Labile tissue?
Continuously replicating and regenerating
What are some examples of Labile tissues?
Epithelium
Haematopoietic tissue
What is the regenerative ability of stable tissue?
Normally undergoing low level replication but can rapidly replicate and regenerate if required
What are some examples of Stable tissue?
Liver
Kidneys
Pancreas
Smooth muscle
Bone
What is the regenerative ability of Permanent tissue?
Cells do not replicate (regenerate)
If damaged must undergo repair (scarring)
How do Labile cells navigate the cell cycle?
Continuously cycling
How do Stable cells navigate the cell cycle?
Enter G0 (Left cell cycle)
But can re-enter the cycle
How do Permanent cells navigate the cell cycle?
Cell permanently in G0
Cannot re-enter the cell cycle
Can regeneration occur with on going chronic inflammation?
No only FIbrous scar REPAIR
What is meant by fibrous repair?
The replacement of functioning tissue with a scar
What are the 4 phases to scar formation?
Bleeding + Haemostasis
Inflammation
Proliferation
Remodelling
What is the Haemostasis stage of scar formation?
Formation of blood clots to prevent blood loss
What is the inflammation stage of scar formation?
Acute then chronic inflammation
Digestion of blood clot occurs
What is the proliferation stage of scar formation?
Increase in the number of cells forming granulation tissue:
Capillaries (Angiogenesis)
Fibroblasts
Myofibroblasts
Extracellular matrix
Which proliferated cells produce the increased amount of Extracellular matrix in scar formation?
Fibroblasts
Myofibroblasts
What is Granulation tissue?
The tissue that proliferates in scar formation consisting of:
Fibroblasts
Myofibroblasts
Extracellular matrix
Capillaries
What is the function of Granulation tissue?
Capillaries supply oxygen and nutrients
Contracts (myofibroblasts) and closes the defect
Essentially fills the gap
What is the remodelling phase of scar formation?
Reduced cell population
Increased collagen in ECM
Myofibroblasts contract
What type of cell proliferates which causes Angiogenesis?
Endothelial cell
What is the role of neutrophils and macrophages in Fibrous repair?
Phagocytosis
Release of mediators that control the inflammatory and repair process
APCs
What is the role of lymphocytes in fibrous repair?
Eliminate pathogens (killer cytotoxic)
Co-ordinate other cells
T and B cells involved in cytokine production
What are the characteristic features of a Fibroblast?
Elongated/spindle/ovoid shaped nuclei
Cytoplasmic extensions
What is the function of the fibroblast tin Fibrous repair?
Secrete collagen and elastin for Extracellular Matrix
What is a myofibroblast?
A fibroblast containing intracellular actin
A cross between fibroblast and smooth muscle cell