tissue healing

quick, summary of wound healing!

BOOM

what GF stimulates angiogenesis?

VEGF (vascular endothelial growth factor) secreted by macrophages

what type of injury results in excessive contraction?

burns can result in excessive skin contraction

what is proud flesh?

exuberant granulation = proud flesh

what is granulation tissue?

granulation tissue is composed of: 1. type 3 collagen secreted by fibroblasts 2. new vessel formation via angiogenesis created in response to GFs secreted by macrophages at site of insult

what are the characteristics of labile, stable, and permanent cells?

most organs have all 3 types 1. labile: continuously dividing (skin, bone marrow, GI, and bladder epithelium) a. easily regenerate b. contain pool of stem cells 2. stable cells: quiescent (liver, kidney, pancreas, endothelial cells) a. limited proliferation and regeneration (except liver) 3. permanent: non-dividing (neurons, cardiac, skeletal muscle) a. no proliferation or regeneration

what are characteristics of the ECM, and what is its importance in terms of wound healing?

network that surrounds cells, composed of interstium and basement membrane 1. regulates cell proliferation 2. sequesters water and minerals 3. scaffold for adherence 4. stores GFs ECM DESTRUCTION = NO REGENERATION = SCAR

what is a keloid scar?

1. a keloid scar is raised, red, inflexible, and causes itching and pain 2. composed of broad, haphazardly arranged bands of highly eosinophilic collagen w/in the dermis, few fibroblasts

what are the stages of a normal healing process?

1. bleeding 2. inflammation: filling w/ collagen and fibrin 3. proliferation: formation of a scar via resporption of blood-collagen and formation of granulation tissue 4. remodelling/maturation: of the scar

what are the characteristics of a scar?

1. dense fibrous type 1 collagen formed over injured tissue 2. begins ~10 days, forms in weeks-months 3. fibro-elastic tissue lacking skin appendages 4. avascular and acellular 5. atrophic (sunken) vs hypertrophic (raised)

what factors, if uncontrolled, can lead to bad wound healing?

1. infection 2. nutrition: VITAMIN C for collagen 3. steroids 4. inadequate blood supply 5. foreign bodies

what is the timescale of tissue repair?

1. inflammation: 0-3 days a. FIBRIN CLOT FIRST b. chemotaxis 2. proliferative phase: .3-10 days a. formation of granulation tissue b. contraction c. re-epithelialization 3. maturation/remodelling: 3-months a. type 1 collagen matrix b. scar formation

what are characteristics of the proliferative phase of tissue repair?

1. macrophage secreted GFs stimulate granulation tissue, consisting of: a. fibroblast secretion of type 3 collagen b. angiogenesis (vessel development) 2. re-epithelialization via epithelial cell migration over wound site 3. contraction of the wound via myofibroblasts

what is skin wound healing by 2nd intention (secondary union)?

1. occurs in large wounds w/ distant edges 2. FIBROSIS > regeneration 3. slow healing 4. more granulation tissue formation 5. more scarring

what is skin wound healing by 1st intention (primary union)?

1. occurs in small wounds 2. REGENERATION >>>> fibrosis 3. fast healing, minimal scarring what every surgeon wants!

what are characteristics of regenerative tissue healing?

1. reconstruction w/ same type of cells 2. occurs only in organs w/ cells capable of regenerating (skin, liver) 3. only occurs if ECM and basement membrane are intact

what are the two types of tissue healing?

1. regeneration: reconstruction w/ same cell types 2. scarring/repair: replacement of injured tissue w/ fibrous connective tissue

what are characteristics of scarring/repair of wounds?

1. replacement of injured tissue by fibrous connective tissue 2. occurs in organs w/ cells incapable of replication (heart) 3. occurs when framework is destroyed

what are characteristics of the remodelling/maturation phase of wound healing?

1. type 3 collagen is degraded by metalloproteinase and replaced with TYPE 1 COLLAGEN 2. formation and reformation of a scar

what is wound dehiscence?

1. wound dehiscence is a deficient scar formation 2. can occur due to mutation/inhibition of metalloproteinase

what are characteristics of heart scarring?

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