5. Healing and Repair

Question 1

What is meant by regeneration?

Answer 1

Proliferation of cells and tissues to replace lost structures

Question 2

What do labile cells do?

Answer 2

Continuously divide replace of dead cells

These tissues contain pools of stem cells, which have enormous proliferative and self renewing ability

Question 3

What are examples of labile cells?

Answer 3

Skin
Gut epithelium
Endothelium
Bone Marrow

Question 4

What are do stable (quiescent) cells?

Answer 4

Conditionally renewing

Divide at a very slow rate normally, but can divide when needed

Question 5

What are examples of stable (quiescent) cells?

Answer 5

Liver
Pancreas
Bone

Question 6

What do permanent cells do?

Answer 6

They have no effective regeneration

Cells that have left the cycle permanently

Question 7

What are examples of central permanently?

Answer 7

Central nervous system
Cardiac muscle
Skeletal muscle

Question 8

Define granulation tissue

Answer 8

A specialised type of tissue

The hallmark of tissue repair

Question 9

What is repair?

Answer 9

Where regeneration cannot occur healing by organisation and progressive fibrosis of granulation tissue occurs

Question 10

What are three important factors of healing?

Answer 10

Ability of the cells of the tissue to regenerate
Type and Extent of Damage
The chronicity of the injury

Question 11

What is healing by fibrous repair?

Answer 11

The process in which tissues are repaired by formation of mature fibrovascular CT

Question 12

What are the stages to form a scar?

Answer 12

Macrophages clear debris 
Fibroblasts proliferate 
In-growth of blood vessels 
Granulation tissue 
Granulation tissue contracts, and collagen is laid down

Question 13

Describe the histology of granulation tissue

Answer 13

New small blood vessels and proliferation of fibroblasts

Question 14

Describe the histology of granulation tissue

Answer 14

New small blood vessels and proliferation of fibroblasts

Question 15

What happens when skin is healed with primary intention?

Answer 15

Degree of disruption

Edges lined up

Question 16

Describe the stages of healing skin by primary intention

Answer 16

Clot formation 
Inflammation 
Epithelial regeneration 
Fibroblast activation 
Neovascularisation 
Scar formation

Question 17

Describe the stages of healing skin by secondary intention

Answer 17

Production of collagen 
Removal of debris 
Maturation and cross linking of collagen 
Removal of cells 
Shrinkage of blood vessels 
Contraction of fibroblasts
Wound contraction 
Scar formation

Question 18

Sequence of events in bone healing?

Answer 18

Haematoma formation
Initial acute inflammation, organisation
Granulation tissue –provisional or soft tissue callus-loosely unites bone
Stem cells in cambium layer of periosteum activate and differentiate into chondrocytes and osteoblasts
Cartilaginous matrix and osteoid produced–mineralised osteoid-BONY CALLUS
Initial bone-haphazard-WOVEN BONE
Remodelled over next few months

Question 19

What happens when injury to CNS?

Answer 19

No effective regeneration of neurones in the CNS

liquefication necrosis and scaring

Question 20

WHat happens when injury in the PNS?

Answer 20

THe axons of the cells may regenerate

Question 21

What are the systematic factors that influence wound healing?

Answer 21

Nutrition
Metabolic status
Circulatory
Hormones

Question 22

What are the local factors that influence wound healing?

Answer 22

Infection
Mechnanical factors
Foreign bodies
Size, location, type of wound

Question 23

What is the aetiology of pressure sores?

Answer 23

Normal frequent adjustment of position in bed is lost due to immobility
Occur over bony prominences –sacrum, heels
Malnutrition
Poor tissue perfusion-vascular disease
Diabetes-can reduce sensation

Question 24

What are the complications of wound healing?

Answer 24

Deficient scar formation
Excessive formation of repair components
Formation of contractures

Question 25

What is exuberant granulation tissue?

Answer 25

“Proud flesh” - the excessive build-up of granulation tissue which protrudes above the surface of the wound and prevents re-epithelialization

Question 26

What are features of keliod scars?

Answer 26

Abnormal healing
Excessive fibroblast proliferation & collagen production
May give rise to large masses
Genetically determined
Commoner in younger individuals
Common in Afro-Caribbeans