Healing and Repair Flashcards

1
Q

What is regeneration/resolution vs Fibrous repair/organisation?

A

Regeneration is growth of cells to replace lost ones - requires connective tissue scaffold to not be lost

Fibrous repair is fibrovascular connective tissue growing into area of tissue loss (significant or complex tissue lost)

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2
Q

What three processes does wound healing involve?

A

Haemostats
Inflammation
Regeneration

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3
Q

What is primary vs secondary intention healing?

A

Primary is regeneration

Secondary is fibrous repair

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4
Q

Which type of repair to labile, stable and permanent cells undergo?

A

Labile/Stable - Regeneration

Permanent - Fibrous repair

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5
Q

How do stem cells replicate?

A

Asymmetrically - produce one ‘self’ cell and one differentiated cell

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6
Q

What is a labile tissue? Give example

A

Proliferate through life - mitosis
E.g. skin epithelia, columnar epithelium of GI and uterus, transitional epithelia of GI, cells of bone marrow and haemopoeitic tissues

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7
Q

What is a stable tissue? Give examples

A

Quiescent but can undergo proliferation if needed
e.g. parenchymal cells of liver, kidneys, pancreas, SMCs, vascular endothelial cells, resting lymphocytes and other WBCs mesenchymal cells e.g.: osteoclasts, fibroblasts

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8
Q

What is a permanent tissue? Give examples?

A

Contain cells that have left the cell cycle and cannot undergo mitosis
e.g. neurones, cardiac myocytes, skeletal muscle cells.

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9
Q

What is required for cells that are terminally differentiated to be able to regenerate? What if they can’t regenerate?

A

Stem cells

Otherwise will undergo secondary intention healing

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10
Q

What are the 4 stages of fibrous repair post inflammation?

A

1) Phagocytosis of debris
2) Proliferation of endothelial cells - angiogenesis - granulation tissue
3) Fibroblasts and myofibroblasts secrete collagen & wound contraction
4) Matures into scar - less vascularisation and contracts

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11
Q

Which cells are unipotent multipotent totipotent?

A

Uni - produce 1 cell line e.g. epithelia
Multi - produce many e.g. haematopoeitic
Toti - embyonic

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12
Q

Why is a scar white and hairless? Why do they stretch?

A

Often no regeneration of melanin or hair follicles etc

Stretch as they produce collagen but not elastin so don’t recoil with growth e.g.

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13
Q

Which three ways can cells communicate in regeneration and repair? Which is the most important?

A

Endocrine - hormones
Paracrine - local mediators e.g. growth factors
Autocrine - cell to cell contact or cell-connective tissue contact

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14
Q

What are growth factors? Which 4 major growth factors are important in wound healing?

A

They are ‘local hormones’ polypeptide protooncogenes that bind to cell surface receptors and stimulate transcription of genes that promote mitosis

1) EGF
2) PDGF
3) VEGF
4) TNF

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15
Q

Name three cells involved in wound healing that produce growth factors

A

Macrophages
Platelets
Endothelial cell

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16
Q

What is EGF? What does it do? Name 3 cells it is mitogenic for

A

Epidermal growth factor - mitogenic for epithelial cells, hepatocytes and fibroblasts.

17
Q

What is VEGF? What does it do?

A

Vascular endothelial growth factor - angiogenesis and vasculogenesis in tumours, chronic inflammation and wound healing

18
Q

What is PDGF? What does it do?

A

Platelet derived growth factor - causes migration and proliferation of fibroblasts SMCs and monocytes

19
Q

What is TNF? What does it do?

A

Tumour necrosis factor - induced fibroblast migration, proliferation and collagenase secretion

20
Q

What is contact inhibition? When is it altered?

A

Where isolated cells will proliferate until touching cells around them and inhibit proliferation.

Malignant cells may not have contact inhibition

21
Q

How would an infected, excisional (loss of tissue), or jagged wound heal?

A

Secondary intention

22
Q

What are the 6 stages of wound healing from injury (with time scales)

A

Seconds to minutes- Haemostasis (contraction of B vessel and clot)
Minutes - hours - Inflammation (neutrophils)
Up to 48 hours - Migration of cells (macrophages, platelets, fibroblasts)
Up to 3 days - Regeneration - granulation tissue (angiogenesis)
7-10 days - Early scaring (vessels still present)
Up to 2 years - Mature scar

23
Q

Name some differences between primary and secondary intention healing

A

Primary - clean non infected wound
Secondary - complex/deep wound, considerable contraction, considerable granulation, scarring, takes longer, infection will delay healing, larger clot at beginning.

24
Q

What kind of factors affect wound healing?

A
Infection
Size/shape of wound
Method of injury 
Blood supply there
Any foreign objects 
Mechanical stress
Age
Diabetes 
Smoking 
Genetic problems e..g Ehlers Danlos
Anaemia
Vitamin deficiency - e.g. Scurvy 
Malnutrition
Drugs - e.g. steroids (inhibit collagen synthesis)
25
Q

Explain how secondary intention leads to loss of function in the heart?

A
Post MI
Fibrous repair
Replaces myocytes
Can't do myocyte contracting function
Can lead to HF
26
Q

What are fibrous adhesions and why do they occur?Where?

A

2nd intention repair that adheres parts of tissue/organs to other parts e.g. bowel to bladder - pain and rupture/blocks tubes e.g. fallopian tube

27
Q

Give an example where 2nd intention healing leads to disruption of complex tissue relationships within an organ

A

Liver - cirrhosis (fibrosis loss of parenchymal cells etc)

28
Q

What is a keloid scar?

A

Overproduction of scar tissue - overproduction of collagen that exceeds the border of the scar.

29
Q

What can cause a joint contracture? What happens if severe?

A

2nd intention healing e.g. afterburns that prevents a limb fully extending for example as scars don’t contain elastin.
If severe can even impair blood circulation

30
Q

What is in granulation tissue? What is it’s function?

A

All inflammatory stuff - fluid, epithelial cells, macrophages, early angiogenesis, fibrin, collagen, etc. Aims to heal ared

31
Q

What is proud flesh?

A

Over granulation - can be seen over height of wound. Can remove by burning or surgically

32
Q

Why are old scars sometimes turned into new wounds in scurvy?

A

Due to increased collagen breakdown in scars, and diminished collagen synthesis in scurvy patients = breakdown of scar and new wound

33
Q

What predisposes to keloid scaring?

A
Afro-caribbean 
Infection
Immunosuppressed 
Diabetes
Foreign bodies

etc

34
Q

Myofibroblasts are really important in primary union?

A

No more in secondary intention

primary union just means primary intention