Wound healing

Question 1

what are the three tissue responses to injury?

Answer 1

-regeneration
-repair
-chronic inflammation

Question 2

what is wound healing dependent on?

Answer 2

-capacity of tissue to regenerate
-type of wound and the degree of damage

Question 3

what are the 6 types of wound?

Answer 3

-abrasion
-avulsion
-incision
-laceration
-puncture
-amputation

Question 4

what are the three types of cells in terms of their renewal

Answer 4

-liable: constant cell renewal
-stable: slow renewal
-permenant: post mitotic

Question 5

what are the two major components that undergo repair?

Answer 5

cells and the extracellular matrix

Question 6

what does the extracellular matrix consist of?

Answer 6

-collagen
-basement membrane
-glycoproteins
-proteoglycans
-elastin

Question 7

what are the steps of healing?

Answer 7

1. haemostasis
   2.inflammation
2. demolition
3. proliferation
4. maturation

Question 8

what are the steps of haemostasis?

Answer 8

1. reaction to injury
2. truggeres platelet aggregation and activation of coagulation cascade
3. haemostatic plug/ clot

Question 9

what is the aims of inflammation?

Answer 9

-trigger phagocytosis
-to trigger plasma proteins and cause clotting factors, complement components and kininogens
-isolate, des

Question 10

what are the steps leading up to inflammation?

Answer 10

1. vasodilation and increased vascular permeability of the blood vessels
2. plasma proteins of fibrinogen and fibronectin are released
3. phagocytes are released

Question 11

what are the symptoms of inflammation?

Answer 11

-rubor/ redness
-calor/ heat
-tumor/ swelling
-dolor/ pain

Question 12

what cells are triggered in inflammation?

Answer 12

-neutrophils
-macrophages
-lymphocytes
-plasma proteins

Question 13

what chemicals are triggered in haemostasis?

Answer 13

-platelets
-fibrin
-fibronectin
-transglutaminases

Question 14

what cells are triggered in demolition

Answer 14

-mainly macrophages
-collagenases

Question 15

what processes are triggered in proliferation?

Answer 15

-granulation
-anglogenisis
-extracellular matrix synthesis
-wound contraction
-epithelial proliferation

Question 16

what processes are triggered in maturation?

Answer 16

-collagen cross linking
-remodelling
-capillary resorption

Question 17

what are the steps of inflammation?

Answer 17

1. vasodilation and vascular permeability
2. plasma proteins of fibrinogen and fibronectin
3. phagocytes are recruited

Question 18

what does proliferation do?

Answer 18

replaces the wound by cells and scar tissue

Question 19

what happens in the formation of granulation tissue?

Answer 19

-angiogenesis to form richly vascularised tissue
-deposition of non-collagenous ECM
-collagen synthesis
-scar tissue deposition

Question 20

what are the growth factors in proliferation?

Answer 20

-EGF
-FGF
-PDGF
-TGFB
-NGF

Question 21

what hormones are involved in proliferation?

Answer 21

insulin, glucagon and thyroid hormones

Question 22

how long does cell regeneration in epithelial wound healing take?

Answer 22

3-7 days

Question 23

what are the steps of granulation?

Answer 23

-endothelial cells spout
-new capillary bed is formed
-cell recruitment where inflammatory cells are triggered
-myofibroblasts released
-wound contraction occurs
-inward migration of myofibroblasts

Question 24

what happens in wound maturation?

Answer 24

-maximum collagen accumulation that takes 2-3 months
-continuous remodelling so continual ECM syntehsis and degredation organisation
-organisation
-collagen cross linking causes increase in tensile strength

Question 25

what causes a keloid scar?

Answer 25

excessive collagen deposition at wound site

Question 26

what are the local wound healing factors?

Answer 26

-type, size and location -vascular supply -oxygen supply -infection -necrosis -foreign material -movement

Question 27

what are the systemic wound healing factors?

Answer 27

-cardiovascular status -nutritional status, vitamin A is essential for epithelial regeneration -diseases such as diabetes or cancer -drugs

Question 28

Give 5 procedures where the eye would have to undergo wound healing

Answer 28

after: -laser surgery such as PKP or LASIK -cataract surgery -glaucoma filtration surgery -proliferative vitreoretinopathy -laser photocoagulation

Question 29

when would the cornea specifically have to undergo wound healing?

Answer 29

-infection -trauma -keratoplasty -refractive surgery

Question 30

What does the nature and extent of the wound healing response depend on?

Answer 30

chemical or mechanical cause. -chemical triggers a superficial response -mechanical triggers a penetrating response

Question 31

What are the 5 refractive and transplant surgeries?

Answer 31

-photorefractive keratectomy (PRK) -Laser-assisted in situ keratomileusis (LASIK) -Laser-assisted sub-epithelial keratectomy (LASEK) -Penetrating keratoplasty (PKP) -Anterior lamellar keratoplasty (ALK)

Question 32

what is PKP?

Answer 32

a full thickness transplant that replaces diseased cornea and is especially useful in cases of endothelial dysfunction

Question 33

What is ALK?

Answer 33

a partial thickness graft of the epithelium and stroma and is for stromal pathologies without epithelial dysfunction

Question 34

what is the process of epithelial wound healing? how long does the process take?

Answer 34

1. rounding off of wound edge, epithelial differentiation disappears 2. stem cells and TACs proliferate 3. loss of cell attachments: hemidesmosomes 4. migration as a sheet along a temporary matrix 5. re-epithelial differentiation/ stratification

Question 35

what is the process of stromal wound healing? What are the symptoms during the healing phase? how long is the healing phase?

Answer 35

1. keratocyte apoptosis at wound site 2. activation and proliferation of fibroblasts 3. migration to wound site 4. differentiation to myofibroblasts 5. ECM remodelling as there is new synthesis of GAGs and collagen and degradation symptoms: -fibrosis and haze -vision loss takes 1-3 years

Question 36

Give the steps to endothelial wound healing

Answer 36

1.cells migrate across Descemet's membrane to compensate regions of loss 2. cells enlarge to fill in gaps in polymegathism and pleomorphism

Question 37

when does endothelial healing need to occur?

Answer 37

if damaged human corneal endothelial cells are unable to regenerate

Question 38

What are the regulators of corneal wound healing?

Answer 38

-tear fluid -growth factors -adhesion molecules -proteolytic enzymes

Question 39

what cell is responsible for wound contraction and why is wound contraction important?

Answer 39

myofibroblast, reduces wound size so faster healing

Question 40

Which cells undergo cell division to generate cells for the process of epithelial regeneration in the cornea and skin?

Answer 40

-cornea: limbal epithelial stem cells; TACs on the basal corneal epithelium -skin: epithelial stem cells in the basal layer; TACs in the basal layer

Question 41

what are the steps of angiogenesis?

Answer 41

1.nearby capillary endothelial cell duplicates 2. this forms a tube of cells 3. this joins up with another tube of cells 4. this forms a new capillary bed at the wound site

Question 42

what are the 3 categories that describe a cells proliferative potential?

Answer 42

-liable -stabile -permanent