Healing and Repair

Question 1

[10-minute video]: Would Healing [Osmosis from Elsevier]

Answer 1

🩸

Question 2

What is healing?

Answer 2

This is the body’s response to injury that attempts to restore normal structure and function.

Question 3

What are two distinct processes involved in healing?

Answer 3

(1) Regeneration: the process by which damaged tissues are replaced with new tissue that is identical in structure and function to the original tissue.

(2) Repair: this is the process by which damaged tissues are replaced with scar tissue, which is not identical to the original tissue but serves to restore the integrity and function of the tissue.

Question 4

Depending on their capacity to divide, the tissues of the body can be categorized into: ____________.

Answer 4

I. labile tissues
II. stable tissues
III. permanent tissues

Question 5

What are labile tissues?

Answer 5

These are tissues that have a high regenerative capacity due to continuous cell proliferation.

Question 6

Give examples of labile tissues.

Answer 6

(1) haematopoietic stem cells in the bone marrow
(2) surface epithelium e.g. stratified squamous epithelia of skin, cuboidal epithelia of ducts draining exocrine organs, columnar epithelium of the GI tract and uterus, transitional epithelium of the urinary tract

Question 7

What are stable tissues?

Answer 7

These are tissues that consist of cells that do not continuously divide but have the potential to proliferate when needed, such as during repair and regeneration. Under normal condition, these cells are in a quiescent state (G₀).

Question 8

Give examples of stable tissues.

Answer 8

◾ liver
◾ kidney
◾ pancreas
◾ smooth muscle

Question 9

Give examples of permanent tissues.

Answer 9

◾ neural tissue
◾ cardiac muscle

Question 10

List the 5 phases of wound healing.

Answer 10

(1) Hemostasis
(2) Inflammation
(3) Epithelialization
(4) Fibroplasia
(5) Maturation

Question 11

Briefly discuss the hemostasis phase of wound healing.

Answer 11

🩸 Immediately after injury, small vessels constrict to provide a measure of hemostasis for 5 to 10 minutes.
🩸 Platelets aggregate in the severed vessels, trigger the clotting cascade, and release essential growth factors and cytokines that are imporant for the initiation and progression of wound healing. More platelets are attracted and a platelet plug is formed to seal the wound.
🩸 The resulting fibrin matrix stabilizes the platelet plug, creating a more durable blood clot.

Question 12

Briefly discuss the inflammation phase of wound healing.

Answer 12

🩸 Mononuclear leukocytes accumulate and are transformed into macrophages.
🩸 Mast cells degranulate, releasing histamine and other mediators of vasodilation and cellular migration.
🩸 Stromal cells release vasoactive substances that make small vessels permeable to molecular and cellular mediators of the inflammatory response.

Question 13

Briefly discuss the epithelialization phase of wound healing.

Answer 13

🩸 Epithelial cells at the edges of the wound migrate across the wound bed.
🩸 Epithelial cells also divide to replenish the wound area.
🩸 In the final stage, the newly formed epithelial tissue matures, cell-cell contacts are established.

Question 14

Briefly discuss the fibroplasia phase of wound healing.

Answer 14

🩸 Fibroblasts are activated and migrate to the wound site.
🩸 They synthesize and depost collagen which forms a scaffold for the new tissue formation.
🩸 New tissue, known as granulation tissue forms at the wound site. This tissue is rich in new blood vessels, fibroblasts and inflammatory cells. Granulation tissue fills the wound, providing a foundation for the subsequent phases of healing.
🩸 Specialized fibroblasts known as myofibroblasts contract the wound, reducing its size and bringing the edges closer together.