Wound Healing

Question 1

What is the difference between parenchyma and stroma?

Answer 1

Parenchyma is functional and stroma is structural.

Question 2

What is the definition of labile cells?

Answer 2

These are constantly dividing. Examples include surface epithelium.

Question 3

What is the definition of stable cells?

Answer 3

They only divide when necessary. Examples include parenchymal cells of liver, pancreas and kidney.

Question 4

What is the definition of permanent cells?

Answer 4

These cells never divide. Examples include neurons, skeletal and cardiac muscles.

Question 5

Is a mesenchymal cells stable, labile of permanent?

Answer 5

Stable

Question 6

Is vascular endothelium stable, labile of permanent?

Answer 6

Stable

Question 7

What two phases are involved in the formation of granulation tissue?

Answer 7

Angiogenesis and fibrogenesis.

Question 8

Describe how angiogenesis occurs from pre-existing vessels

Answer 8

There is vasodilation mediated by nitric oxide and increases permeability mediated by VEGF. The basement membrane will be destroyed by MMPs and the endothelial cells will then migrate to the stimuli and begin to proliferate.

Question 9

Describe how angiogenesis occurs from stem cells

Answer 9

The cells are derived from endothelial precursor cells and are found in bone marrow. They will migrate to area

Question 10

What is the meaning of MMPs?

Answer 10

Matrix metalloproteinase

Question 11

What is the three stages of wound healing and what are their time lengths?

Answer 11

Inflammation: 6-8 hours
Proliferation: 5-7 weeks
Maturation: Weeks

Question 12

What is the meaning of healing by first intention?

Answer 12

This is where there is a clean cut wound, no infection and there is a limited amount of tissue loss.

Question 13

What is the role of the blood clot that forms within the first stage of wound healing?

Answer 13

To seal the wound to prevent it from infection and dehydration, stop bleeding and act as a scaffold.

Question 14

During inflammation, what is the first cell to appear?

Answer 14

Neutrophils: within 24 hours

Question 15

When do fibroblasts start to proliferate?

Answer 15

24-72 hours

Question 16

What are some factors that are responsible from fibroblast migration?

Answer 16

PDGF, TNF, FGF

Question 17

What cell eventually replace neutrophils?

Answer 17

Macrophages

Question 18

Fibroblasts will initially lay down a provisional matrix. What are the components of this?

Answer 18

Collagen III, fibrin and fibronectin

Question 19

What will the provisional matrix be replaced with?

Answer 19

Type three collagen

Question 20

What happens during maturation?

Answer 20

There will be very little inflammatory cells and re-vascularisation. The granulation tissue will be replaced with dense collagen material to form scar tissue.

Question 21

What cells carry out contraction of the wound?

Answer 21

Myofibroblasts: these are intermediate cells between smooth muslces cells and fibroblasts.

Question 22

what percentage of the original strength is achieved by week 3 during wound healing?

Answer 22

70-80%

Question 23

What is healing by secondary intention?

Answer 23

There is not a clean cut, large size, infection and a large amount of tissue loss.

Question 24

What are some factors that affect wound healing?

Answer 24

Protein malnutrition, vitamin C deficiency , Glucocorticoids, infection, presence of foreign substance, areas with poor blood supply (eg foot)