stiner- wound healing Flashcards
epidermis has how many layers? which layer is responsible for cell division
5, Stratum basale (germinativum)
epidermis characteristics
not vascularized,
karatinized/nonkaratinized
which skin layer is vasularized?
dermis
intact endothelial surfaces are ______
antithrombotic
what is thrombosis
formation of blood clot inside blood vessel
2 vasodilators and platelet inhibitors?
NO
prostacyclin
Prostacyclin does what
decrease thromboxane
decrease PDGF
thromboxane does what
platelet aggregation, vasoconstrictor too
PDGF does what
platelet adhesion to vessel walls
what does NO do?
inhibits platelet recruitment and adhesion
break in skin causes what
hemostasis
what is hemostasis?
process that causes bleeding to stop
3 phases of wound healing
inflammtion phase
proliferation phase
remodeling and maturation phase
3 parts of inflammation phase
intial injury and vascular response
blood coagulation
inflammation
after initial injury endothelial cells secrete what
von Hillebrand factor
seratonin
thromboxane
hemostasis steps
- vasoconstriction
- temporary blockage by platelet plug
- blood coagulation/ clot formation
what is Hemorrhaging
bleeding
clot formation is a result of ______ converted to _____
fibrinogen to fibrin
vasoconstriction, an immediate response, is done by _____ and ______ , decreasing blood flow
prostaglandins, thromboxanes- released from damaged membranes (rational behind applying pressure)
platelet plug forms as platelets attached to what
exposed collagen
activated platelets release what? and what do they do
cytokins. stimulate recruitment of more platelets and vasoconstriction.
20 minutes post-wound what happens and by what
vasodilation by histamine
histamine aids in what
blood vessels become leaky, easier for leukocytes to infiltrate.
coagulation happens how long after blood vessel injury?
almost instant
primary hemostasis
formation of platelet plug
secondary hemostasis
Clotting factors, which are proteins, form fibrin strands
Strengthens the seal
(happens at same time)
Exposure of blood to subendothelial collagen activates the _______ pathway
intrinsic pathway
Exposure of blood to subendothelial tissue factor on fibroblast also activates ______ pathway
extrinsic pathway
intrinsic pathway beings where?
collagen surface
(pro)thrombin in is present in which pathway
extrinsic
primary function of thrombin
convert fibrinogen to fibrin
The clot is maintained by the continued activation
VIII and IX
what is fibrinolysis
prevent to much fibrin from being formed.
what carries this process out?
plasminogen binds fibrin and is converted to plasmin by tPA
tPA made by what
endothelial cells
what mediates the binding of Xa and IXa to the phospholipid surfaces expressed by platelets
Calcium
what does calcium do in wound healing?
mediates binding of lXa and Xa to the phospholipid surface expressed by platelets
what is required for the addition of a carboxyl group to glutamic acid residues on factors II, VII, IX and X
vitamin K
what is a Key target for anticoagulant drugs warfarin and coumarins
vitamin K
mechanisms that regulate platelet adhesion and coagulation cascade
- Protein C
- antithrombin
- tissue factor inhibitor
- Plasmin
- Prostacylin
major endogenous anticoagulant
Protein C
Protein C is activated by what and dependent on what?
thrombin, vitamin K
tissue factor inhibitor does what
restricts the action of tissue factors
Prostacylin does what
leads to activation of cAMP inhibits platelet activation by decreasing cytoplasmic Ca2+
fist immune cells to arrive…second?
neutrophils
macrophages
neutrophil function
scavenge for bacteria and clear wound of cellular and foreign debris
eosinophil
killing of antibody coated parasites
macrophages function
killing bacteria, phagocytizing bacteria but also mediate angiogenesis synthesize nitric oxide form fibrous tissue also stimulate cells that reepithelialize the wound, create granulation tissue, and lay down a new ECM
parts of proliferation phase
angiogenesis
epithelialization
granulation/tissue formation
proliferation phase begins how many days after wound?
4 days
characterized by presence of what
fibroblast
angiogenesis
Endothelial cells migrate to site to repair damaged vessels
new vascular networks
what is the main cell type responsible for granulation tissue
fibroblast
what is granulation
fibroblasts and endothelial cells replace the immature matrix with a collagen-fortified ECM forming new granulation tissue
endothelial cells are attracted to places to form new vessels by what and what
fibronectin and angiogenic factors (macrophages and platelets secret these things)
Endothelial growth and proliferation directly stimulated by
hypoxia and presence of lactic acid
When adequate vascularization achieved what happens
Hypoxia and lactic acid-induced growth factor release ceases and angiogenesis stops
epithelialization (cell and what factors)
Keratinocytes secrete TGF-β and KGF
what do TGF-β and KGF do?
Stimulate cell division and repair of damaged epithelium
remodeling phase begins when?
week after wound
initial component of ECM during this phase?
fibronectin
