Topic 4: Tissue Repair and Healing Flashcards Preview

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Flashcards in Topic 4: Tissue Repair and Healing Deck (19):
1

When does inflammation resolve?

-no more loss of structural cells
-phagocytosis clean up

2

What is primary intention healing?

-lacerations with neat, clean edges or fractures where bony elements are precisely approximated
-ideal situation for wound healing
-no gap between sides of wound or tissue loss

3

What is secondary intention healing?

-large open wounds with tissue loss
-large inflammatory response
-haematoma and large fibrin meshword
-scarring and scabs
concurrent infection

4

What are the four phases of tissue repair?

haematoma --> proliferation --> repair (anabolic and catabolic) --> remodelling

5

What is a haematoma?

-body of blood outside a vessel
-plasma and fibrin meshwork
-scaffolding by fibin
-stems bleeding (tamponade)

6

When can a haematoma become unhelpful?

large size, excessive duration, inside muscle compartment or brain

7

What is the process for the formation of a haematoma?

damaged vessel --> platelets + RBC --> clotting cascade --> platelet coagulation factors --> platelets activated by thrombin and aggregate --> platelets and fibrin scaffold

8

Proliferation

increase in number of immune cells and fibroblasts

9

Repair - catabolic

break down of dead, damaged, dying tissue by macrophages (phagocytic activity)
*occurs immediately except with bone repair

10

Repair - anabolic

-neoangiogenesis - formation of new blood vessels from pre-existing vessels, driven by cytokines
-fibroplasia and matrix deposition by fibroblasts
-collagen and ECM synthesis
-re-epithelialisation

11

Remodelling

final aggregation, orientation, arrangement of collagen fibres
-type III --> type I collagen
-contraction of wound from secondary to primary

12

What are some factors affecting tissue repair?

Age
-neonates: greater capacity for healing but lower energy stores
-elderly: decreased skin thickness and collagen content, loss of elasticity, slow healing
Malnutrition
Alcohol
-increase infection incidence
-diminished host resistence
-affects re-epithelialisation, collagen production, wound closure
Stress
-deregulation of immune system
-delayed wound healing
-physiological behavioural patterns: poor sleep, poor nutrition, decreased exercise, increased alcohol, increased cigarettes and drugs

13

How does muscle tissue heal?

-fibre degeneration (myonuclear death, impaired continuity of sarcolemma, myofibrils --> sarcomere units)
-rupture of vessels = haematoma
-damaged cells attract WBC (neutrophils, macrophages)
-phagocytosis
-satellite cells proliferate --> differentiate into myoblasts which fuse onto myotubules and release interleukins
-myotubes attempt to grow through scar tissue

14

How do ligaments heal?

-subcutaneous bleeding but quickly tamponaded
-macrophages act early
-proliferating fibroblasts close gap
-new tissue is fragile, viscous, stiff, weak
-stimulus directs matrix remodelling

15

Why is bone so strong?

-collagen fibres = tensile strength
-calcium salts = compressional stregnth

16

What are pre-requisites for bone healing?

adequate blood supply and mechanical stability

17

How does bone heal?

-no healing by scar tissue
-callus stage --> bridging between inflammatory and repair phase; bone is weaker at this stage

18

What is mechanobiology?

how physical forces and changes in mechanical properties of cells and tissues contributes to the development, cell differentiation, physiology and repar
-stimulates neovascularisation

19

What is mechanotransduction?

-process by which the body converts mechanical loading into cellular responses --> structural changes
-stimulates or initiates cell migration