Lecture 4: Healing and repair 1

Question 1

Possible outcomes post-injury

Answer 1

• Resolution- recovery of cells suffering non-lethal damage
• Regeneration- replacement of cells with functional duplicates
• Repair through scar- replacement of dead cells with non-functioning scar tissue

Question 2

Phases of healing

Answer 2

• Vascular responses and inflammation
• Proliferative phase
• Remodelling phase

Question 3

Vascular response- haemostasis

Answer 3

• Immediate vasoconstriction- stops bleeding, reduce bacterial exposure
• Next vasodilation- necessary for tissue recovery
• Blood clotting

Question 4

Inflammation- clean and clear

Answer 4

• Immune cells, growth factors, enzymes and nutrients taken to wound
• Involves neutrophils and other phagocytes, including macrophages
• Many other cells and chemical signalling mechanisms involved

Question 5

Acute inflammatory stage

Answer 5

• Redness
• Heat
• Swelling
• Pain
• Associated loss of function

Question 6

Proliferation

Answer 6

• Angiogenesis- formation new blood vessels
• Fibroblasts lay down granulation tissue- fibroplasia
• Epithelial cells migrate from surrounding skin/tissue
• Wound contraction

Question 7

Maturation

Answer 7

• Remodelling continues to occur over long period of time

* Regains strength

Question 8

Purpose of early vascular response and inflammation

Answer 8

• Remove tissue agent
• Decrease tissue damage
• Prepare wound environment for healing

Question 9

Coagulation

Answer 9

• Changes in platelets occur
• Coagulation factors form fibrin strands
• Fibrin mesh closes wound and creates matrix for cell migration

Question 10

Inflammatory mediators

Answer 10

• Prostaglandins and histamines- increase vasodilation and permeability
• Macrophages- release factors attracting fibroblasts to increase collagen synthesis
• Platelets- release growth factors controlling fibrin deposition and angiogenesis

Question 11

Macrophage

Answer 11

• Prominent inflame cell
• Phagocytosis
• Promotion and resolution of inflammation
• Support cell proliferation and regeneration
• Produce growth factors, prostaglandins and complement factors

Question 12

Proliferation- fibroplasia

Answer 12

• Fibroblasts proliferate and migrate

* Collagen and other growth factors produced- also stim angiogenesis

Question 13

Re-modelling

Answer 13

• Collagen- immature, gel-like, little tensile strength
• Collagen fibres realign- increase tensile strength
• Wound breaking strength at 20% by day 21
• Final wound breaking strength 70-80% of normal

Question 14

Delayed healing/union

Answer 14

• Infection
• Mechanical factors
• Co-morbidities

Question 15

Outcome of impaired healing

Answer 15

• Scarring and fibrosis
• Excessive wound contracture
• Hypertrophic scars
• Keloid scars
• Deformity
• Dysfunction