Wound healing
Wound healing
1. Induction of acute inflammatory response by the initial injury 2. Debridement (surgical or natural by phagocytosis) 3. Formation of a healthy granulation bed 4. Angiogenesis and fibroplasia 5. Epithelialization ("cover & seal", contact inhibition) 6. Wound contraction 7. Remodeling of tissue elements to restore function and to increase wound strength as much as possible
Proliferate and differentiate into myoblasts
Activation of satellite leads to?
oxygen, nutrients, and more phagocytic cells and chemical mediators
Angiogenesis allows the influx of blood with what?
Neovascularization
Angiogenesis is also called?
Fibrinolytic enzymes
Dissolution of fibrin clots by?
Make contact with similar cells
Epithelial cells make contact with ______ cells form all sides of the wound and seal it
Proteolytic enzymes
Epithelial cells us what enzymes to sever the connection between the clot and the wound surface?
Keeping the wound moist
Epithelialization can be aided by keeping the wound?
Contracture
Excessive wound contraction
Angioblasts, fibroblasts, & myofibroblasts
Granulation tissue contains what cells?
3-5 days
Granulation tissue forms in how many days?
Over time
Granulation tissue represents a temporary scaffolding that changes ___________ ___________
Reconstruction
Granulation ↔ ?
Suppresses adrenal gland and immune system
How can glucocorticoids/ steroids be bad?
Often continues for months
How long does the maturation phase of healing often continue for?
Become highly organized
In the Maturation phase of healing collagen fibers are initially almost random, but now become?
Repair promoting macrophage function
Perhaps anti-inflammatory drugs may not be such a good idea if they are inhibiting what?
Inflammation
Platelets, neutrophils, and macrophages
1. Inflammation 2. Proliferation 3. Remodeling/Maturation
What are the three phases of wound healing?
Glucocorticoids (aka steroids)
What are: •Anti-inflammatory drugs •Slow the migration of phagocytic cells to the site of injury •Cause phagocytic cells already in the area to become less active •Mast cells exposed to steroids are less likely to release histamine and other chemicals that promote inflammation
Satellite cells
What assist with repair of damaged fibers?
Some fibroblasts can
What can transition into myofibrils
Excessive bleeding
What causes clots, bacteria, infection, prolonged inflammation, exudation, pus?
Excessive fibrin deposition
What causes fibrous adhesions?
Stable cells
What cells are usually low level of replication, stimulation can lead to rapid division increases (quiescent)?
Permanent cells
What cells cannot reproduce themselves after birth, stop dividing during prenatal life (nondividing)?
Epithelial cells
What cells from the surrounding healthy tissue migrate into the wound
Continously Dividing cells
What cells proliferate throughout life (labile)?
Produce collagen which gradually develops more strength - for strong scar tissue
What do fibroblasts produce?
Influence wound healing
What do these influence? - site of the wound - mechanical factors - size of the wound - infection - circulatory status - nutritional and metabolic factors - age of patient or wound
Epithelialization
What does covering or sealing of the wound called?
- Filling in the wound defect - epithelization - contraction
What does repair involve?
• return to normal structure and function, minor damage w/o complications • can take up to 2 years
What happens to the structure and function if a wound has healed by regeneration?
Myofibroblasts
What have features of both fibroblasts and smooth muscle cells?
Ischemia
What impairs collagen synthesis, cell death, infection, prolonged inflammation?
First intention
What intention is regeneration/resolution?
Second intention healing
What intention of healing? • large, open defects and infected wounds • formation of granulation tissue
First intention healing
What intention of healing? • wounds with minimal tissue loss • always preferred IF possible
Sutured surgical wound
What is an example of first intention healing?
Cirrhosis of the liver
What is an example of internal contracture?
Degloving
What is an example of second intention healing?
Scar tissue
What is composed of collagen, restores strength but not function?
Angiogenesis
What is it called when capillary buds sprout out of vascular endothelial cells on wound margins?
Regeneration
What is it called when damaged tissue is replaced with healthy tissue - ideal "cure, good as new"
Resolution/ regeneration
What is it called when injured tissue is replaced by cells of the same type? - restoration of the OG function and structure
Dehiscence
What is it called when wound pulls apart (5-12 days after suturing) due to wound infection or excessive strain?
Repair
What is it called when: • destroyed tissue is replaced by connective tissue •fills in the lesion and restores tensile strength but can not carry out physiologic functions of the destroyed tissue - second best "fix-up, patch-up", "scar"
Contraction
What is shrinking of the wound called?
Natural debridement
What is slow, and uses inflammation and phagocytosis for debridement?
Debridement
What is the first absolutely essential step in wound healing?
"fill in, seal, and shrink the wound
What is the saying for wound healing
Phase 3 Maturation Phase of Healing
What is: - also called the scar remodeling phase - continuation of collagen deposition, tissue repair, and wound contraction - scar tissue is remodeled and gains its maximum strength
Keloid scar
What kind of scar raised, extends beyond original boundaries, invades surrounding tissue?
Remodeling and maturation phase
What phase has fibroblasts?
Proliferative phase
What phase: - macrophages, fibroblasts, lymphocytes - new tissue formation?
Inflammatory phase
What phase: - platelets, neutrophils, and macrophages - coagulation and hemostasis?
Multinucleated
What provide multiple copies of genes to speed up production of enzymes and structural proteins?
Granulation tissue
What tissue has a pink, soft, granular appearance?
Surgical debridement
What type of debridement speeds up healing?
Hypertrophic scar
What type of scar is raised, remains in original boundaries of the wound, regresses over time?
Fibroblasts
What: - enter the area and proliferate - deposit fibrous structural proteins
Type 3; Type 1
"immature" _________ collagen is replaced by stronger ________ collagen
Inflammatory process
Both resolution and repair begin early during what process?
1st Intention
Cannot do __________ __________________ now because epithelialization has caused wound edges to become sealed down; would need to create new wound edges
Angioblasts
Cells that form new blood vessels
Angioblasts and fibroblasts
Chemical mediators secreted by macrophages promote growth of
Phagocytosis
Clean up of particulate matter in the inflammatory exudate happens by?
0.5mm
Contraction alone may move the wound edge by ______mm per day
Remodeling/maturation
Just fibroblasts
Proliferation
Macrophages fibroblasts, and lymphocytes
Parallel lines
Most collagen fibers are in?
Wound bed
Myofibroblasts anchor themselves to the ___________ _____________ and exert pull on neighboring cells
Neighboring cells
Myofibroblasts establish connections with ___________?
+N*on-*S*teroidal *A*nti-*I*nflammatory *D*rugs
NSAID's
Macrophages and neutrophils
Proliferation stage has debridement by ______________ and _______________
Reconstruction and maturation
Repair involves what two overlapping phases?
Second intention
Repair is what intention
Repair is to 2nd intention
Resolution is to 1st intention a _________ is to _________
Stress
Tension lines orientation depends on the _________ placed on then skin during normal movement
False
True or False: There is greater granulation tissue and wound contraction in 1st intention healing
Myoblasts
What are embryonic cells which fuse to create the muscle fibers?
Diabetes mellitus, obesity, wound infection, inadequate nutrients, drugs (steroids, NSAIDs), tobacco smoke
What are some examples of predisposing disorders for dysfunctional wound healing?
Parenchymal of organs and mesenchymal cells
What are some examples of stable cells?
1. Inflammation 2. Proliferation 3. Remodeling & Maturation
What are the 3 phases of wound healing?
1. formation of a healthy granulation bed 2. filling in the wound defect 3. covering or sealing the wound (epithelialization) 4. shrinking the wound (contraction) 5. wound maturation
What are the 5 steps of wound healing?
- Ischemia - Excessive bleeding - Excessive fibrin deposition
What are the causes of dysfunctional wound healing?
C. Epithelial
Which cell type is most likely to lead to cell resolution? A. cardiac B. liver C. Epithelial
B. macrophages
Which cell types infiltrates a wound during both the inflammation phase and the proliferation phase? A. fibroblasts B. macrophages C. lymphocytes D. neutrophils E. platelets
↓ excess inflammation
Why are glucocorticoids/ steroids good?
Slower
Will wounds orthogonal to the tension lines will heal faster or slower?
Faster
Will wounds that are parallel to the tension lines heal faster or slower?
Migrate into the scaffolding and organize into vessels
With angiogenesis new endothelial cells migrate into the _________ and organize into ___________
Overlapping
Wound healing occurs in 3 ______________ phases
Fibrin and trapped cells
Wound is initially sealed off by a blood clot containing?