principles of wound healing

Question 1

what are the three phases of wound healing?

Answer 1

• haemostasis and inflammation
• proliferation (fibroplasia)
• maturation

Question 2

explain the first stage of wound healing

Answer 2

haemostasis and inflammation:
injury:
1. platelet aggregation
2. release of growth factors and inflmmatory mediators
* neutrophills, lymphocytes and macrophage ativity

Question 3

describe the second stage of wound healing

Answer 3

proliferation (fibroplasia)
angiogenesis - granulation tissue, fibroblasts and collagen formation - myofibroblast contraction

Question 4

describe the third stage of wound healing

Answer 4

maturation: remodelling of collagen - type III replaced by type I

Question 5

brefiely describe the process of haemostasis

Answer 5

1. tissue damage
2. blood leakage from vessels
3. activation of clotting cascade - intriinsic and extrinsic
4. platelet aggregation and release of cytokines
5. stabilisation of platelet plug by fibrin formation

Question 6

explain what occurs in the inflammatory phase (what cells are invloved)

Answer 6

1. ovelap w/ haemostasis
2. occurs in the first 72 hours after injury
3. vasodilation (follows transient vasoconstriction during haemostasis)
4. cytokines in the fibrin clot attract WBCs, initially neutrophils, then macrophages
5. destruction of cells by phagocytosis helps to ‘ clean up’ bacteria and devitalised tissue

Question 7

explain what occurs in the proliferation phase of wound healing

Answer 7

• some ovelap with inflammatory phase
• formation of granulation tissues - formed of macrophage, fibroblasts, and new blood vessels (gives granulation tissue red appearance)
• fibroblasts proliferate and produce new extracellular matrix, elastin and collagen
• formation of new epithelial tissue (pale pink)
• myofibroblasts cause wound contraction
• contact inhibition

(repair phase)

Question 8

explain what occurs in the maturation phase of wound healing

Answer 8

• Remodelling
• Type III (immature) collagen replaced by Type I (mature) collagen
• Cross linking of collagen
• Change in components of extracellular matrix
• Increase in tensile strength
• Takes weeks to months

Question 9

what pateint factions affect wound healing?

Answer 9

• age
• co-morbidities (HAC, diabetes)
• nutrition status (hypoproteineamia)

Question 10

what wound factors affect wound healing?

Answer 10

• infection
• location (tension, movement, local blood supply)

Question 11

what other factors affect wound healing?

Answer 11

concurent treatment:
- corticosteroids -delay all stages of wound healing
- radiation - tissue fibrosis and vascular scaring

Question 12

expalin contact inhibition

Answer 12

when new epithelial cells come in contact with each other the stop the process of further cell division resulting in a smooth surface formed

Question 13

why do old animals have slower wound healing?

Answer 13

rateds of cell devsion and cell remodeling are slower