Normal wound healing and types of wound Flashcards
How long does the lag phase of wound healing last?
1-5 days
What is the principle process occurring during the lag phase of wound healing?
Inflammation
Haemostasis occurs within which phase of would healing?
Lag/ inflammatory - IMMEDIATELY
How do vessels respond to injury?
Transient vasoconstriction then vasodilation after 5-10 minutes
Describe the primary clot formed during haemostasis.
Aggregate of fibrin, clotting factors and platelets
Acute cells of inflammation
Neutrophils
How do neutrophils act when they enter a wound site?
Degradation of necrotic tissue via release of proteolytic enzymes and control of bacterial infection via superoxide radicals
Chronic cells of inflammation
Lymphocytes and plasma cells
Intermediate cells of inflammation
Monocytes -> Macrophages
How do macrophages act when they enter a wound site?
Remove degenerate neutrophils, necrotic tissue and debris by phagocytosis. Secrete regulatory factors of wound healing
How long does the repair phase of wound healing last?
6-16 days
What are the three aspects of the repair phase of wound healing?
Connective tissue repair, wound contraction and epithlialisation
Describe the repair of connective tissue in a wound
Fibroblasts migrate into the wound secreting ground substance which replaces the primary clot. Collagenous (t3 initially then to t1) ECM is put down. Fibroblasts apoptose which forms a granulation tissue scar. Secondly angiogenesis occurs (these disintegrate after used)
When does wound contraction occur?
5-9 days post injury
Describe the cells associated with wound contraction.
Specialised myofibroblasts containing actin microfilaments
When does scar remodelling occur in a wound?
14-16 days post-injury
Remodelling results in what changes in the wound site?
Reduced cellularity, thickened collagen bundles, cross-linking and reorientation along the lines of tension.
How does hypoproteinaemia affect wound healing?
Reduced cell proliferation and ground substance production
How does hypovolaemia affect wound healing?
Reduced delivery of oxygen and nutrients to the wound site
How does reduced oxygen tension affect wound healing?
A high oxygen demand within wound cells (high metabolic demand)
How does uraemia affect wound healing?
Reduced cellular metabolism and therefor granulation tissue and epithelial formation.
How does steroid therapy affect wound healing?
Reduced protein synthesis, capillary growth, fibroblast proliferation and epithelialisation. Inhibit inflammation!
How does a vitamin C deficiency affect wound healing?
Collagen synthesis (remember ascorbic acid)
How does a Zinc deficiency affect wound healing?
Reduced epithelial cell and fibroblast multiplication - reverse transcriptase and DNA polymerase
How do cytotoxic drugs/ radiotherapy affect wound healing?
Drugs target and kill actively dividing cells such as those in a healing wound
How does dehydration affect wound healing?
Drying of wound surface can reduce cellular migration and proliferation
How does bacterial infection affect wound healing?
Increases inflammation, affects wound pH, reduced fibroblast activity, degradation of ECM and ground substance
How does a antiseptic solutions affect wound healing?
Contain cytotoxic detergents
How does skeletal muscle respond to injury?
If little disruption to the sarcolemma then regeneration is possible. If the sarcolemma is severely disrupted then fibrous tissue bridges the gap
How do peripheral nerves respond to injury?
If cut sprout axons which grow down the endoneural tube
Clean wound
Elective surgical wounds not entering the respiratory, urogenital or gastrointestinal tracts with no break in asepsis and primary closure
Clean-contaminated wound
Surgical wounds involving the respiratory, urogenital or GI tracts without significant contamination or only minor breaks in asepsis
Contaminated wound
Fresh (
Dirty wound
Old (>4-6hr) traumatic wounds. Or traumatic wounds contaminated with foreign material or severe amounts of devitalised tissue. Surgery in the presence of abscessation
Abrasion
Partial thickness, loss of epi and part of dermis
Avulsion
Tearing of tissue from its attachment
Degloving injury
Low-velocity avulsion of skin due to rotational forces (RTA)
Incision
Sharp trauma, smooth-edged wound, minimal tissue trauma
Laceration
Sharp trauma, irregular wound, tearing of tissues and trauma to underlying tissue
Puncture wound
Minimal superficial damage, substantial deeper damage, significant risk to deep organs
Burn
HOT/ COLD WOUNDS
