Topic 4 - Tissue Repair and Healing

Question 1

Haematoma Phase

Answer 1

A body of blood/clotting of blood outside the vessel

Question 2

Functions of a Haematoma

Answer 2

1. plug blood
2. early scaffolding for cells migration, proliferation and early repair
3. form from trauma involving the vessel

Question 3

Bad Haematoma

Answer 3

1. in a constrained limited space - intermuscular - can lead to secondary ischaemic cell death
2. excessive in size = excessive scar tissue
3. excessive in duration

Question 4

Proliferation Phase

Answer 4

1. Prolif of R and NonR IC - macrophages, B+T, team microphage, dendritic, NKC
2. Prolif of fibroblasts –> differentiate into specialised types

Question 5

Repair Phase - Catabolic

Answer 5

Phagocytosis of D,D,D tissue and foreign cells if infection present
Degree of catabolic activity evident in inflam
In optimal healing, anabolism predominates

Question 6

1. Neo-angiogenesis

Answer 6

Formation of new BV from pre existing vessels –> scaffolding from haematoma allows this
Stimulated by cytokines and influenced by mechanical loading

Question 7

2. Fibroplasia

Answer 7

Activated fibroblasts continually reorganise and synthesise new tissue
Deposition of new fibre greatly exceeds degradation

Question 8

3. Matrix deposition

Answer 8

Laying down of granulation tissue (immature collagen and ECM)
Early in wound collagen III predoms but later switched to I
Wound suffused with GAGs and fibronectin

Question 9

4. Re-epithelialisation

Answer 9

Migration of cells from periphery of wound

Wounds involving mouth, lining of airways, skin and gut

Question 10

Remodelling Phase

Answer 10

Involves final aggregation, orientation and arrangement of collagen fibres and ECM into a “mature form” (Cyto+ML)
collagen deposited and degraded in equilibrium seeking fashion until no changes and equilibrium reached - wound can now mature

Question 11

Wound Contraction - Remodelling phase

Answer 11

Results in part from proliferation of specialised fibroblasts
Healing tissue slowly develops enhanced mechanical properties and architecture, driven by mechanical loading across the wound site

Question 12

Mechanobiology

Answer 12

Careful movement and loading of healing tissue is good - stimulates angiogenesis and new tissue - as long as not too much and is graduated
Mechanotherapy occurs through process of mechanotransduction

Question 13

Mechanotransduction

Answer 13

1. mech load on muscle/tendon/bone/ligament
2. ECM experiences “stress and strain”
3. Force transferred to cell walls = deformation
4. Intracellular senses trigger altered osteocyte etc. activity including release of catabolic enzymes and synthesis of proteins