-
After injury
- the tissue works to eliminate the offending agent
- contain the damage
- prepare surviving cells for replication
-
Healing
- combination of regeneration on fibrosis (scarring)
- heart and brain are not able to regenerate so they scar
- Extensive exudate with fibrin will cause scarring
-
Regeneration
- tissue growth that replaces lost structures
- must have intact connective tissue scaffold
-
what regulates adult cell populations
- cell proliferation
- differentation
- apoptosis
-
Proliferation
- physiologic;hormaonal
- pathologic; injury, cell death
- signals may inhibit or stimulate
- can recruit cell into the cell cycle
-
Cell cycle
- G1, presynthesis
- S DNA synthesis
- G2 Premitotic
- M mitosis
- G0 resting state
-
continuesly dividing tissues
- cells proliferate throughout life replacing dead cells
- surface epithelium, the intestinal tract, bone marrow
-
quiescent cells
low level replication but still capable of dividing in response to stimuli; liver, kidney, fibroblasts, smooth muscle, endothelial cells
-
Nondividing cells
neurons, skeletal muscle, cardiac muscle
-
Stem cells
- prolonged self renewal capacity
- asymetric replication
-
What do you use in knockout experiments
embryonic stem cells
-
Adult stem cells
- located in niches
- restricted differentiation capability
- liniage specific
-
Where in the liver are stem cells
- canals of Hering; junction of hepatocyte and bile duct
- only differentiate if direct hepatocyte proliferation is not possible
-
MAin VEGF receptor
VEGF-2
-
Epidermal growth factor
- Source; platelets, macrophages, saliva, urine , milk, plasma
- Function; stimulates keritinocytes and fibroblasts to proliferate
-
Transforming growth factor alpha
- source; macrophages, T cells,
- function; stimulates replication of hepatocytes, and epithelial cells
-
Hepatocyte growth factor
- source; mesechymal cells
- function; stimulates epithelial, endothelial, and hepatocyte proliferation
- stimulates mobility
-
Vascular endothelial growth factor
- source; mesenchymal cells
- function; increase vascular permeability, endothelial cell proliferation
-
PDGF
- source; platelets, macrophages, smooth muscle, endothelial cells
- chemotactic; PMNs, macrophages, fibroblasts, smooth muscle cells,
- activation of all cells
- mitogenic for fibroblasts, endothelial cells, smooth muscle
- stimulates production of, proteases, fibronectin,
- angiogenisis and would contraction
- inhibits platelet aggrigation
- regulates integrin expression
- alpha granuals
-
FGF
- source; macrophages, mast cells, t cells, endothelial cells,
- chemotactic for fibroblasts
- mitogenic for fibroblasts and keritocytes
- wound contraction
- angiogenesis
- centrally involved in would repair
- form resivoirs of inactive factors
-
TGF beta
- source; platelets, t cells, macrophages, smooth muscle, fibroblasts
- chemotactic ; macrophages, neutrophils, lymphocytes, fibroblasts,
- stops proteasis; tissue inhibitor of proteases
- down regulates intigrins
- anti-inflammatory effect
- promotes fibrosis by stimulation chemotaxis
-
keratinocyte growth factor
- fibroblasts
- stimulates keratinocyte migration, differentation, and proliferation
-
ILGF
source; macrophages, fibroblasts
-
TNF
- macrophages, mast cells, lymphocytes
- activates macrophages, regulates the cytokines
-
interlukins
- macrophages, mast cells, lymphocytes
- many functions
-
interferons
- lymphocytes, fibroblasts
- activates macrophages,
- inhibits fibroblast proliferation and synthesis of MMPs
-
Tyrosine kinase
- most growth factors
- Ras
- PI3
- phospholipase C
- activated Ras binds to Raf and then activates a MAP kinase
- PLC leads to IP3 and DAG, increased cytosol calcium
-
JAK / STAT
- cytokines
- stats are transcription factors
-
G protein receptors
- glucogon, epi, chemokines, ACTH
- generates cAMP
-
steroid hormaone recptors
- diffuse directly into membrane
- intranuclear trascription factors
-
p53
cell cycle inhibitor gene
-
Transcription factor response time
- the rapid response time needed by the cell does not permit for new synthesis, it rather relys on post transcriptional modification that allows migration into the necleus
- modification; dimerization, phosphorilation, release of inhibitors
-
cell cycle regulation
- CDKs; protein kinases become active after binding cyclin
- each step needs different kinases
- CDKs are regulated by catabolism or inhibitors
- p53 works by expressing cyclin inhibitor, this stops the cell cycle until the damage is corrected or can induce apoptosis
-
Function of hypertrophy and hyperplasia
the restore functional capacity, not reconstruct original anatomy
-
after nephrotmy
the other kidney will hypertrophy to make up for the lost one
-
collagen
- skin and bone; type 1
- cartilage; type 2
- basment membrane; type 4
- elastin type 3
- formed as individual alpha chain, form a triple helix
-
Defect in marfans
fibrilin 1
-
classic ehlers-danlos
collogen v
-
vascular ehlers danlos
collogen III
-
osteogenesis imperfecta
collegen I
-
type II collegen
- catillage
- any grooming disorder
- arachnidactyl
-
four cell adhesion proteins
- immunoglobins
- cadherins; calcium dependent
- intigrins, cell-cell adhesion as well as cell to to ECM
- selectins
-
what two cell adhesion molecules are transmembrane
cadherins and intigrins
-
fibronectin
- lots of adhesion
- in hemidesmosoms
-
most abundant glycoprotein in the BM
laminin
-
an angiogenesis inhibitor
osteonectin
-
proteoglycans and hyaluronic acid
- bind large amounts of water and GAGs
- give turner and resists compression
-
scarring
a fibroproliferative response that pathces rather then restores
-
fibrosis
ECM depositing at a site of injury
-
the sequence of healing
- inflammatory response to eliminate stimulus and remove injured tissue
- proliferation and migration of parechymal and connective tissue
- angiogenisis; new blood vessels
- synthesis of ECM proteins
- tissue remodeling
- wound contraction
- granulomas are a hallmark of healing
-
monocyte chemotaxis
PDGF, FGF, TGF-B
-
Fibroblast migration
PDGF, EGF, FGF, TGF-B, IL-1
-
fibroblast proliferation
PDGF, EGF, FGF, TNF
-
-
collagen synthesis
TGF-B, PDGF
-
collagenase secretion
PDGF, FGF, EGF, TNF, TGF-b inhibits
-
embryonic vessel development
vasulogenesis
-
branching of pre-existing blood vessels
angiogenesis
-
steps of angiogenesis
- NO dialates preexisting vessel
- VEGF induces increased permeability
- metalloprotinases degrade BM
- plasminogen activator disrupts cell cell interaction
- ECs migrate to angiogenic stimulus
- EC mature into capillary tubes
- periendothelial cells are recruited
-
Growth factor receptors in angiogenesis
- VEGF and the angiopoetins
- VEGFR2; tyrosine kinase receptor
-
recruits smooth muscle
PDGF
-
stabilizes newly formed vessels
TGF-B
-
Three stapes to scar formation
- Fibroblast migration and proliferation
- ECM deposition and scar formation
- Tissue remdeling
-
Type III collogen in in granulation tissue then is replaced by type I
-
-
Gelatinases
degrade amorphous collagen
-
TIMP
tissue inhibitor metalloproteinases
-
cutaneous Wound healing
- epidermal appendages do not regenerate
- induction of inflammation
- granulation tissue formation, type III collagen
- ECM deposit and remodeling with wound contraction
-
First intention wound healing
- opposed edges, clean surgical cut
- 0 hours; incision is filled with blood
- 3-24 hours; meutrophils infiltrate
- day 3; macrophages replace neutrophil;s
- day 5; granuloma fills incision space, neovasculation
- week 2; inflammation and edema are done
- month 2; scar is now connective tissue devoid of inflammation covered by epidermis. strength will continue to accrue
-
second intention wound healing
- greater inflammation response
- more scaring
- thinner epidermis
- thicker granuloma
- most significantly wound healing is characterized by contraction; myofibriblassts
-
wound strength
- 1 week 10%
- within 3 months 70-80%
-
Excessive repair with large scar
keloid
-
palmer contracture
too much contractor in the healing process from inflammation
-
glucocorticoids
inhibit collegen synthesis
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