Skin - Wound healing Flashcards

1
Q

What are the four phases of wound-healing?

A

Haemostatic

Inflammatory

Proliferative

Maturation & Remodelling

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2
Q

What happens in the first stage of wound-healing, haemostasis?

A

Within minutes post-injury, platelets (thrombocytes) aggregate at the injury site to form a fibrin clot. This clot acts to control active bleeding (haemostasis). The speed of wound healing can be impacted by many factors, including the bloodstream levels of hormones such as oxytocin.

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3
Q

What happens in the second stage of wound-healing, inflammation?

A

Bacteria & debris are phagocytosed and removed by macrophages & neutrophils, and factors are released that cause the migration and division of cells involved in the proliferative phase.

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4
Q

What happens in the third phase of wound-healing, proliferation?

A

angiogenesis:
new blood vessels are formed by vascular endothelial cells

fibroplasia (collagen deposition) & granulation tissue formation:
fibroblasts grow and form a new, provisional extracellular matrix (ECM) by excreting collagen and fibronectin

epithelialization:
concurrently, epithelial cells proliferate and ‘crawl’ atop the wound bed, providing cover for the new tissue

contraction:
wound made smaller by the action of myofibroblasts, which establish a grip on the wound edges and contract themselves using a mechanism similar to that in smooth muscle cells. When the cells’ roles are close to complete, unneeded cells undergo apoptosis.

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5
Q

What happens in the last phase of wound-healing, maturation and remodelling?

A

Collagen is remodeled and realigned along tension lines and cells that are no longer needed are removed by apoptosis.

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6
Q

Explain the difference between primary and secondary intention wound healing.

A

First intention (primary union) - restoration of tissue continuity occurs directly, without granulation.

  • Involves epidermis and dermis without total penetration of dermis; healing by process of epithelialization
  • When wound edges are brought together so that they are adjacent to each other (re-approximated)
  • Minimizes scarring
  • Most surgical wounds heal by primary intention healing
  • Wound closure is performed with sutures (stitches), staples, or adhesive tape
  • Examples: well-repaired lacerations, well reduced bone fractures, healing after flap surgery

Second intention - wound repair following tissue loss is accomplished by filling of the wound with granulation tissue.

  • The wound is allowed to granulate
  • Surgeon may pack the wound with a gauze or use a drainage system
  • Granulation results in a broader scar
  • Healing process can be slow due to presence of drainage from infection
  • Wound care must be performed daily to encourage wound debris removal to allow for granulation tissue formation
  • Examples: gingivectomy, gingivoplasty, tooth extraction sockets, poorly reduced fractures
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7
Q

Propose strategies to improve wound healing.

A

Keep granulation tissue moist.
Keep up nutrition - vitamins, calcium Oxygen therapy
Maintain constant temperature Keep wound clean.

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8
Q

What are Halsted’s Principles of Surgery?

A
  1. Handle tissues gently
  2. Control hemorrhage carefully
  3. Preserve blood supply
  4. Observe strict asepsis
  5. Minimize tissue tension
  6. Appose tissues accurately
  7. Eliminate dead space
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