Tissue Healing And Repair

Question 1

Compare and contrast the regenerative capacity of stable cells

Answer 1

• Long life-span and row rate of division
• Often can multiply when needed.
• An adequate connective tissue framework is needed for regeneration to occur

Question 2

Compare and contrast the regenerative capacity of permanent cells

Answer 2

• No capacity for mitotic division in post natal life

- Scar tissue is formed when damaged

Question 3

What occurs during the preparative phase of healing?

Answer 3

• Wound defect is filled with blood
• acute inflammation
• bleeding is arrested (platelets and clotting proteins)
• Scab is formed
• prevents further blood loss
• binds edges of wound
• prevents entry of microorganisms
• prevents dehydration
• protection against physical irritation
• clot retraction draws wound edges together

Question 4

Discuss the importance of fibronectin

Answer 4

Fibronectin plays a vital role in stability wound during the early stages of repair. It’s a glycoprotein that is able to bind to

• collagen
• fibrin
• proteoglycan
• cells surface
• bacteria etc.

Question 5

Discuss the events occurring in the epidermis during the repair of a small wound

Answer 5

• Increase mitosis and budding if basal cels results in bridging of wound deficit
• Growth and migration of local epithelial cells helps to fill deficit and restore epithelial continuity
• If damage to the basal layer was minimal then epidermal architecture is normal

Question 6

Discuss the events occurring in the dermis during the repair of small wound

Answer 6

• Migration and division of fibroblasts
• Invasion of wound by fibroblasts
• collagen synthesis and deposition of fibroblasts
• Gradual strengthening of scar tissue (collages cross-linking)

Question 7

Discuss the events occurring in the epidermis during the repair of a wound with significant cell loss

Answer 7

• Restoration of epithelial continuity is initially not possible as the tissue deficit cannot be bridged by cellular budding(bridge formation)
• also no foundation exists for epithelial cells to migrate over

Question 8

Discuss the events occurring in the dermis during healing by secondary intention

Answer 8

• Development of granulation tissue.
• Migration and division of fibroblasts
• Invasion of wound defect
• invasion of wound defect by capillaries
• Collagen synthesis and deposition by fibroblasts
• Gradual strengthening of scar tissue
• Collagen cross linking
• Type 1 collagen replaces type 3
• Alignment of collagen fibres along stress lines
• Achievement of maximum scar strength is approximately 6 months
• Granulation tissue serves as a foundation for spread of epithelial cells but loss of normal epidermal architecture results at the site of healing
• Scar devascularisation occurs

Question 9

Compare and contrast the regenerative capacity of labile cells

Answer 9

• Divide actively throughout life replacing cells which are normally lost
• Loss of cells from tissue acts as a mototic stimulus
• Adequate numbers of labile cells must survive for repair to be possible