Tissue injury

• What is the top layer of skin called?

  Epidermis
• What is the middle layer of skin called?


  Dermis
• What is the lower layer of skin called?

  Hypodermis
• What is the nature of the epidermis?

  Keratinised waterproof barrier for protection of internal structures
• What is the nature of the dermis?


  Location of hair follicles, sebaceous glands, nerve endings, blood vessels and sweat glands
• What is the nature of the hypodermis?

  Fat tissue
• What are the 5 stratum of the epidermis starting from least superficial to most superficial?

  Basale, spinosum, granulosum, lucidum, corenum
• Which stratum is the largest and flakes off during exfoliation?

  Stratum corneum
• What is important about the cells at the bottom layer of the epidermis?

  They have larger nuclei and make new skin cells
• What are the epithelial extensions from the epidermis into the dermis?


  Rete ridges
• What are the types of wounds?


  1. Incision

  2. Laceration

  3. Abrasion

  4. Puncture

  5. Penetration

  6. Cotusion

  7. Haematoma
• What is a clean surgical wound?


  Incision with no inflammation or break in sterile technique
• What is a clean-contaminated surgical wound?


  Incison through tracts under uncontrolled conditions where contamination is encountered
• What is an example of a clean surgical wound?

  Removal of a skin mole
• What is an example of a clean-contaminated surgical wound?


  Elective procedure on the bowel
• What is a contaminated surgical wound?


  Incision has a major break in sterile technique where there is gross spillage of the GI tract
• What is an example of a contaminated surgical wound?


  Removal of the gall bladder which results in bile spillage
• What is a dirty surgical wound?


  Incision the perforates the viscera, encountering acute inflammation
• What is an example of a dirty surgical wound?


  Contamination of an open trauma fracture
• What is a 1st degree burn?

  Superficial burn that affects the outer layer of the epidermis
• What is a 2nd degree burn?

  Superficial partial through the epidermis into the dermis
• What is a 3rd degree burn?

  Full thickness burn down to the hypodermis
• What is a 4th degree burn?

  Burn that extends to the bone
• What is another name for would repair?

  Wound intention
• What is primary wound repair?


  Clean edges brought together without tension
• What is tertiary wound repair?

  Delayed primary closure for a dirty wound
• What is secondary wound repair?


  Healing by granulation at the base of the wound
• What are the 4 phases of wound repair?


  1. Hamostasis

  2. Inflammation

  3. Proliferation

  4. Maturation and remodelling
• What is the haemostasis phase?


  Immediate vasoconstriction and blood clotting in response to tissue injury
• What is the inflammatory response phase?

  1. Vasodilation and increased vascular permeability

  2. Migration of inflammatory cells and fibroblasts

  3. Release of cytokines and PDGFs
• What do fibroblasts do in the inflammatory response phase?


  Release extracellular matrix and collagen
• What is the proliferation phase?


  Formation of granulation tissue, angiogenesis and wound contraction
• What do PDGFs do in the proliferation phase?


  Initate inflammatory cell proliferation
• What cells are responsible for angiogenesis?

  Endothelial cells
• What cells are responsible for wound contraction?

  Myofibrils
• What is the remodelling phase?


  Wound maturation where scar becomes less vascular
• In remodelling, what is type III collagen replaced with?


  Type I collagen
• How long does it take for a wound to become waterproof?

  48 hours
• How long does it take a wound to fully mature?

  12-18 months
• What is a hypertrophic scar?

  Excessive production of collagen