0514 Tissue healing, wound repair and fibrosis

Question 1

What are the 2 types of tissue repair what are the differences between them

Answer 1

Tissue regeneration and tissue replacement (fibrosis). Tissue regeneration = regeneration that will resemble original. Tissue replace = generally will not resemble original

Question 2

Which primary factor determines whether a wound will heal by tissue regeneration or fibrosis

Answer 2

Whether the stroma and parenchyme are damaged (damaged = fibrosis)

Question 3

List the 4 functions of the extracellular matrix

Answer 3

Support and Form, storage of growth factors, retention of minerals (hard tissues) and providing turgor (retention water)

Question 4

3 components of the extracellular matrix

Answer 4

Fibrous proteins (e.g. collagens and elastins), Adhesive glycoproteins (fibronectins and laminins) and a gel of proteoglycans and hylauronan

Question 5

List the 4 broad steps (phases) of tisseu repair by fibrosis

Answer 5

Angiogenesis, migration and proliferation of fibroblasts, deposition of new ECM and remodeling (organisation and maturation of fibrous tissue)

Question 6

What is angiogenesis? What growth factors regulate this

Answer 6

Development of vessel ‘buds’ from exiting vasculature (aka neovascularisation). It is regulated by growth factors such as VEGF and TGF-Beta in the ECM

Question 7

What stimulates growth factor VEGF and therefore angiogenesis

Answer 7

Cytokines and hypoxia

Question 8

Describe what is happening during days 1-3 of healing via primary intent

Answer 8

Scab forms, wound fills with thrombus, Neutrophils migrate to clot, Basal cells deposit basement membrane, Fibroblast produce granulation tissue and angiogenesis initiates

Question 9

When does an immature scar first form during healing by primary intent

Answer 9

Days 3-7

Question 10

Describe what is happening during days 3-7 of healing via primary intent

Answer 10

Immature scar forms, neutrophils mostly replaced by macrophages, continued epidermal regeneration and granulation tissue production

Question 11

Describe what is happening after 2 weeks - months of healing via primary intent

Answer 11

Remodeling of scar. Reduced to no oedaema or vascular proliferation (scar is paler), fiborus union (tensile strength) and continued fibroblast proliferation

Question 12

What are the primary differences of secondary healing compared to primary healing

Answer 12

Think the Gaping SIDE Wound.
Increased granulation, more scarring, more inflammation, greater destruction of surrounding supporting tissue, Edges not approximated, More wound contraction

Question 13

List at least 5 factors that can affect wound healing

Answer 13

Nutrition, glucocorticoids infection or foreign bodies, mechanical factors (e.g. shear stress), individual variables (pre-existing conditions), drugs and radiotherapy

Question 14

What is exuberant granulation

Answer 14

Proliferation of granulation tissue above skin, preventing re-epithelialisation. It is a result of abnormal wound healing

Question 15

What are Keloids

Answer 15

It is a scar made primary of type 1 or 2 collagen due to the thickinening of the subcutaneous layer of collagen bands

Question 16

Compare hypertrophic scars to keloids

Answer 16

Hypertrophic scars appear similar to keloids but flatten over time and scarring is limited

Question 17

Does an ulcer heal by primary or secondary intention

Answer 17

It heals by secondary intention (destruction of parenchyme and stroma and edges not approximated)

Question 18

Is cirrhosis of the liver a picture of normal regeneration?

Answer 18

Cirrhossis of the liver is not normal regeneration (It is replacement of liver tissue via fibrosis and regenerative nodules). It results in loss of liver function

Question 19

Following major surgery, would stiches be left in situ longer
in a diabetic patient than another patient of the same age?

Answer 19

Yes. Diabetes affects; circulation (narrow vessels =less blood and oxygen to wound), immune function (lowers efficiency of immune system) and neuroapthy ( uncontrolled blood glucose can lead to loss of sensation = increased risk for wound site)