Wound Healing Flashcards
What is wound healing
It’s 2 major processes
-body’s response to injury to try and restore normal structure and functioning
- regenerative
- repair / resolution
What is regeneration
/proliferation of parenchymal cells to replace damaged area with exact same type to cell
What does functional and structural repair mean
- restoration of organ function ( most common ) compensatory repair
- restoration of complete organ structure
What is repair
-healing occurring by proliferation of CT tissue ( myofibroblasts , fibroblasts ) and laying down of collagen at injured area forming a fibrocystic scar
What does repair depend on
1 type of tissue damaged
2 Extent of damage
3 nature of damage
List the steps of repair
1 hemostasis
2 inflammation
3 proliferation
What is granulation tissue ( describe it )
Differentiate from granuloma
- hallmark of wound healing. Pink and has granular appearance on surface
- foci for granulamatous inflammation
List the 3 phases of granulation tissue formation
1 inflammatory phase
2 clearance phase
3 in growth of granulation tissue ( Angiogenesis and fibrosis )
What is
Angioblast
Hemongioblast
Vasculogenesis
- stem cell which differentiates into embryonic blood vessels
- stem cells which develop into embryonic blood vessels and hemapoietic cells
- development is of embryonic blood vessels and blood from angioblast and hemongioblast
What is angiogenesis and 2 ways it comes about
-development of adult blood vessels through
1 from existing blood vessels
2 from stem cells from endothelial precursor cell ( EPC )
How does angiogenesis from stem cells come about
- Endothelial precursor cells migrate to site of angiogenesis from bone marrow
- proliferate and mature into vessels
How does vessels dilation and increased permeability come about in angiogenesis
How is the basement membrane degraded
- vessels dilation mediated by nitric oxide
- VEGF increased permeability
-matrix metalloproteinase degrade endothelial
How does angiogenesis by pre-existing vessels come about
/vessels increase width and permeability
- basement membrane degraded
- endothelial cells migrate to site of angiogenesis and proliferate , mature and reshape into vessels
What happens to pericytes during angiogenesis
What are they the pericytes
/they accumulate as vascular smooth muscles
-peri endothelial cells
What is fibrogenesis
-accumulation of blood vessels and fibroblasts and myeoblasts at site of injury surround by collagen 3 and ground substance
What 2 processes make granulation tissue
1 angiogenesis
2 fibrogenesis
What is wound contraction
When does it occur
How does it occur
- reduction of size of injured area
- 2-3 days after injury and ends after 2 weeks
- myofibroblasts have contractile apparatus which contract and reduce the size of wound
3 types of cutaneous skin repair
1 1st intension
2 2nd intension : secondary union
3 tertiary
List the steps of cutaneous wound healing
1 blood clotting / homeostasis
2 inflammation
3 proliferation : granulation tissue formed
4 maturation : tissue remodeling , wound contraction,
Criteria for 1• union , 2• union and 3• union
- clean wound ,uninfected
- minimal tissue loss ,cut margins close to each other
- infected wound , extensive tissue loss , cut margins greatly distanced , no clean cut wound
- clean cut wound intentionally left open due to risk of enclosing infection
Describe homeostasis and its function during wound healing
- this is when the wound is filled with blood wc clots
- seal wound from dehydration
- top part of clot dries up forming seal Called scab to prevent infection
- scaffold for inflammation cells and other healing cells
Describe inflammation phase of wound healing
/WBC’s migrate to site of inflammation ( neutrophils later replaced by macrophages by day 3 )
-in 1st 24 hours neutrophils degrade debit and bacteria
Describe proliferation phase of wound healing
-fibrosis and angiogenesis and granulation tissue formed ( 24-72 hours )
/epithelium at edge proliferates ( after 24 hours) , deposit basal membrane and fuse at middle
-wound now has deep single layer of epi
-by 5th day layer stratified and wound re-epithelized
How are fibroblasts recruited to site of injury
-some are local and others migrate to site after stimulated by chemoattractants
