healig regeneration and repair Flashcards
Name three types of stem cells, the definition of each and examples of each
Unipotent- The stem cell can differentiate into one type of cell only (eg. Epithelia)
Multipotent- The stem cell can differentiate into more than one type of cell eg. haematopoetic stem cells
Totipotent- The stem cell can differentiate into all types of cells (eg. embryonic stem cells)
where are stem cellls found in the intestine, epidermis, and liver?
intestine- at the bottom of the crypts
epidermis- in the basal layer adj to basement membrane
liver- between hepatocytes and bile ducts
three types of tissue (classified into there regeneration abilities), definitions and examples
Labile- rapid proliferation, short lived cells eg. epithelia, haematopoetic cells
Stable- Normally slow proliferation, can be fast if need be eg. liver, bone, fibrous tissue and endothelium
Permanent- Cannot proliferate eg. neural tissue, skeletal muscle and cardiac muscle
What are the requirements for regeneration to take place? 3
need an intact CT scaffold
Tissue damage can’t be extensive
damage must be in labile or stable tissue
Describe the process of scar formation
sec to mins- haemostasis min to hrs- acute inflammation hrs-days- chronic inflammation 2-3 days- granulation tissue formation 7-10 days- early scar formation weeks to years- scar maturation
what does granulation tissue consist of?
Chronic Inflamm cells
fibroblasts and myofibroblasts
newly forming blood vessels
Function of granulation tissue? 3
contracts and closes the hole
fills the gap
capilleries supply oxygen and nutrients and cells
What types of cells are involved in fibrous tissue and what are their functions? 3
Inflammatory cells- Phagocytose debris and produce chemical mediators
Endothelial cells- proliferate stimulating angiogenesis
fibroblasts and myofibroblastss- synthesise collagen and wound contraction
Describe the type of wound in primary intention
Incised, closed wound
no infection
minimal tissue loss
Minimal clot and granulation tissue in primary intention
Describe what takes place in healing by primary intention? 3
Epidermis regenerates
Dermis undergoes fibrous repair
Minimal scar formed
Describe the type of wound in healing by secondary intention
excisional wound, extensive tissue loss, separated edges, infected maybe
You get an open wound filled with granulation tissue
Describe what takes place in healing by secondary intention
considerable wound contraction and substantial scar contraction
Describe the process of bone breakage
- Haematoma formation- fills the gap and surrounds the injury
- Granulation tissue forms
- Soft callus formation- fibrous tissue and cartilage form within which woven bone forms
- hard callus formation- woven bone forms
- Lamellar bone forms- remodelled in line with mechanical stress
What properties of the wound affect wound healing? 7
location type size shape mechanical stress blood supply infection or foreign bodies
What general properties affect wound healing?
age diabetes obesity drugs (eg. steroids) malnutrition vitamin deficiencies anaemia
Name 6 complications of fibrous repair
disruption of the complex tissue relationships
Keloid scar
Excessive scar contraction
adhesions–>compromised organ function and blockage of tubes
insufficient fibrosis
loss of function
Why does a donor site for skin grafts able to grow back quickly
skin taken at a very superficial level
so no disruption to the complex tissues
Where is type one collagen found?
bones, tendons, ligaments, cornea, skin, sclera, blood vessels hollow organs
where is type 4 collagen found? and what secretes it?
basement membrane
epithelial cells
Describe the process of how collagen is made?
ppt alpha chains synthesised in the ER
enzymatic modification including vit C dependent hydroxylation
alpha chains align and form cross linkages
forms procollagen triple helix
this is secreted
procollagen then cleaved to form tropocollagen
tropocollagen polymerises to form microfibrils and then fibrils
fibrils–>fibres
Describe what is meant by contact inhibition
Signalling molecules on cell surfaces inhibit proliferation
Such as cadherins and integrin
this is altered in cancer
8 functions of growth factors?
inhibition of division locomotion contractility differentiation viability angiogenesis activation
Name four types of growth factor
epidermal
platelet derived growth factor
vascular
TNF
