Flashcards in Tissue repair Deck (60)
What does it mean to repair a tissue?
Both restoration of tissue architecture and function after an injury
Complete recovery rarely achieved
What are the two mechanisms of tissue repair?
Regeneration of injured tissue
Replacement of lost tissue
Which mechanism of tissue repair require cell proliferation of intact or altered cellular matrix?
Stem cells produce a baseline cell population which do ____ or ____.
Proliferate, die via apoptosis
What are the types of continuously dividing (labile) cells?
Skin basal, hematopoietic, hair follicles and GI cells
What does the G0 phase look like for the continuously dividing cells?
What are the stable cells and what does it mean to be stable?
Liver, kidney, lung alveoli, bone, breast, endocrine, adipose, vessels
Only need to proliferate when necessary
What does the G0 phase look like for stable cells?
What are the permanent tissues and what does that mean?
Neurons in CNS, ganglia in PNS, cardiac, skeletal muscle
Cannot divide functionally
What are some characteristics of continuously generating cells?
Can easily regenerate after injury with a infinite life span
Dependent on age and health
Contains pools of stem cells
Immune positive for CD34, CD117, Ki67
What are the three locations for skin stem cells?
Epidermis, sebaceous gland, hair follicle bulge
What are the actions of growth factor?
Stimulate cell division and proliferation
Promote cell differentiation and survival
What some examples of growth factors?
Epithelial growth factor (skin, fibroblasts)
Transforming growth factor (hepatocytes, epithelials)
Platelet derived growth factor (s muscle, cytokines)
Granulocyte growth factor
What does each growth factor have on its target cell?
A specific receptor
When cells are injured and proliferate what is released?
Where do the cell injury responsive cytokines come from?
Damaged tissue, inflammatory cells, macrophages and vascular endothelial cells and fibroblasts
What are the two forms of the extracellular matrix?
Interstital matrix and basement membrane
What does the extracellular matrix do?
Sequesters water and mineral from circulation
Stores presynthesized growth factors
Gives cells a scaffolding upon which to adhere and do their assigned tasks
What does the ECM regulate overall?
Proliferation, movement, and differentiation of cells living in or on it
If the ECM is completely destroyed what happens?
It cannot regenerate and a scar forms
When does regeneration occur in labile tissues?
All the time, can make as much as needed
When does regeneration occur in stable tissue?
A limited extent, only some can come back or compensate for lost tissue
Only occurs if the residual tissue is healthy and intact
When does regeneration occur in permanent tissue?
Pretty much never and will always form scar tissue
What are the steps to injury healing?
3. Blood clotting
4. Granulation tissue - scab,eschar
5. Wound contraction
6. Wound recovery
7. Scar tissue
If an injury is too severe...
regeneration can't happen
What are the four components used in regeneration mediated by growth factor?
New vessel formation VEGF
Fibroblast proliferation FGF, TGF
Fibroblast synthesis of immature scar - type 3 collagen
Fibroblast remodeling with mature scar - type 1 collagen
What is an eschar?
Granulation tissue does not contain....
Cross linked collagen
What are the three examples of wound healing?
First intention - sew shut
Second intention - leave open
Third degree burn