2-Wound Healing

Question 1

wound healing

definition

Answer 1

complete restoration of og architecture and function of tissue or anatomic part after an injury
-regeneration

wound repair is not fully recovery just functional compromise

Question 2

phases of healing process

Answer 2

1. inflammatory
2. proliferative
3. remodeling

Question 3

inflammatory phase

Answer 3

up to 3 days after wound
-platelets, neutros, macros
-clot formation + inc vessel perm so neturos migrate into tissue + macros clear debris

Question 4

proliferative phase

Answer 4

day 3- weeks later
-fibroblasts, myofibros, endothelial cells, keratinocytes, macros
-granulation tissue and collagen III deposition
-angiogenesis/epi cell prolif, clot dissolution, wound contraction by myofibros

if vit C or copper def then delay healing

Question 5

remodeling phase

Answer 5

starts early as 1 week-6+ months
-fibroblasts
-collagen III replaced by type I to inc strength of tissue

delay if zinc deficiency

Question 6

macrophage functions

Answer 6

1. removal of injured tissue- phagocytosis
2. antimicrobial activity- mitric acid, ROS
3. chemotaxis + prolif of fibros - TGF-beta, IL-1, TNF
4. angiogenesis- VEGF, PDGF
5. deposition/remodel of ECM- TGF-beta, PDGF, TNF, IL-1,

Question 7

PDGF

Answer 7

secreted by activated platelets and macros
-induce vascular remodel and smooth muscle cell migration
-stims fibros growth for collagen syn

Question 8

FGF

Answer 8

stims angiogenesis by promote prolif of endo cells
-also stims prolif of fibros

Question 9

EGF

Answer 9

stims cell growth via tyrosine kinases
-EGFR, ErbB1

Question 10

metalloproteinases

Answer 10

tissue remodelling

Question 11

VEGF

Answer 11

stims angiogenesis

Question 12

angiogenesis

Answer 12

capillary budding
-endo cells prolif to form new vessel
reg by VEGF

Question 13

fibrogenesis

Answer 13

fibroblast activatin and prolif
-deposits collagen

stim by TGF-beta

Question 14

granulation tissue

Answer 14

3-5 days later granulation tissue is apparent
-pink, soft, granular appearance
-progressively acc CT matrix via cicatrization so dense fibrosis scarring
-only temporary

Question 15

histologic appearance granulation tissue

Answer 15

1. prolif of fibroblasts surrounded by abundant ECM
2. new thin walled delicate capillaries
3. fibros and capillaries in loose ECM
4. scattered macros + other inflamm cells, if early stage then numerous macros, myofibros, vessels
   -late stage is less vascular, more matrix and fibros

Question 16

cicatrization

Answer 16

combo of collagen depo + contraction + devascularization to form scar
-contraction could lead to deformity and functional impairment (contracture)
-more gran tissue = more contraction > inc risk of organ impairment

Question 17

factors influence tissue repair

Answer 17

1. infection-delays healing
2. diabetes-abnormal healing
3. steroids- weakness of scar bc inhibits TGF-b so fibros diminished
4. ischemia- from arteriosclerosis, diabetes, obstructed venous drain
5. foregin body- steel, glass, bone
6. nutritional status- protein def, vit C def,

Question 18

first intention healing

Answer 18

closed, non-infected wound
-margins are opposed, healing occurs directly with minimum gran tissue
-epithelial regen (epithelization) predoms fibrosis

Question 19

second intention healing

Answer 19

-wound margins are non-opposed aka too separated
-large tissue defects more necrotic debris so more exudate/fibrin need removal
-more gran tissue formed
-large gaping, infection, foreign body wounds
-too many myofibros = contraction within 6 wks

Question 20

contracture

Answer 20

exaggeration of contraction

reduction in size of wound via second intention bc exposed surface dec by gradual regen of surface epi
-severe deformity, limit joint mobility

usually with burns or hollow viscera (male urethra, esoph, intestine) > stenosis

myofibroblasts can produce collagen and contract so hybrid properties

Question 21

keloid

Answer 21

acc of exuberant amount of collagen I and III so prominent raised scars, lack glands and hair follicles
-hereditary predis african americans
-disorganized structure
-extends borders
-few myofibros

Question 22

hypotrophic scars

Answer 22

atrophic, depressed/sunken

hyperpigmented appearnace bc loss of collagen and ground substance
-acne, stretch marks

Question 23

hypertrophic scars

Answer 23

structurally similar to keloid but not progress beyond 6 mo and not recur after excision
-inc in type III collagen in parallel organization
-stays confined to borders of og scar
-numerous myofibros
-no predis

Question 24

proud flesh

Answer 24

xs gran tissue, abnormal cell growth and ECM prod in wound healing
-will protrude above skin so prevent closure and hinder epithelization
-bleed excessively if traumatized
-must cauterize or surgery