Wound Healing Flashcards
Regeneration
Replacement of lost tissue with cells
of the same type
Regeneration Cell Types
- Labile
- Stable
Labile cells
divide constantly rapid regeneration (skin, lymphoid organs, bone marrow, mucous membranes, GI,
GU)
Stable cells
regenerate when an organ is injured (liver, pancreas, kidneys, bone cells)
Repair
Healing as a result of lost cells being replaced by connective tissue
Which is more common, repair or regeneration?
Repair
Which is more complex, repair or regeneration?
Repair
What usually results in scar formation?
Repair
Repair cell type
Permanent (CNS, cardiac muscle)
Three types of repair
- Primary Intention
- Secondary Intention
- Tertiary Intention
What is primary intention?
- Takes place when wound edges are approximated
* i.e. – surgical incision, paper cut
Three phases of primary intention?
- Initial Phase
- Granulation Phase
- Maturation Phase and Scar Contraction
How long does the initial phase of primary intention last?
3-5 days
What happens during the initial phase of primary intention?
- Blood fills into incision forms clot – provide matrix for WBC migration
- Inflammatory reaction occurs
- Injured area -fibrin clot, RBCs, neutrophils, debris
- Macrophages clean up (eat) debris, fibrin fragments, RBCs
- Fibrin clot is the mesh framework for future capillary growth and migration of epithelial cells
How long does the granulation phase of primary intention last?
3 days to 5 weeks
What happens during the granulation phase of primary intention?
- Granulation tissue: fibroblasts, capillary sprouted (angioblasts), various types of WBCs, exudate, loose - semifluid ground substance
- Fibroblasts – immature connective tissue – secretes collagen which once organized and restructured will strengthen the site
- Wound is pink and vascular with numerous red granules (young budding capillaries) are present
- Wound is friable, at risk for dehiscence, resistant to infection
- Surface epithelium at the wound edges regenerate in a few days with migration of a thin layer of epithelium across the wound surface
How long does the maturation phase of primary intention last?
7 days, and can last for several months or even years
Overlaps with the granulation phase
What happens during the maturation phase and scar formation?
- Further organization of collagen
- Remodeling process occurs
- Myofibroblast movement causes contraction of the wound and wound edge closure
- Mature scar is formed – avascular and pale; can be more painful than during granulation phase
What is secondary intention
- Wounds from trauma, ulceration, infection
- Characterized by large amounts of exudate, irregular wound edges, extensive tissue loss
- Larger inflammatory response (more debris, more cells, more exudate)
- Debris may need to be cleaned away or debrided before healing can take place
- Infected wound healing by primary intention my reopen (dehiscence) and healing by secondary intention takes place
Main differences between secondary and primary intention?
- Greater defect
- Gaping wound edges
- Heals from edges inward and from bottom of wound upward
- More granulation tissue
- Larger scar
What is Tertiary intention?
- Delayed primary intention
- Healing occurs with delayed suturing of a wound
- Contaminated wound left open and sutured closed after the infection is controlled
- Usually, results in a larger, but deeper than 1° or 2°
How are wounds classified?
- Cause (surgical, non-surgical, acute, chronic)
- Level of contamination
- Depth of tissue infected ( superficial, partial thickness, full thickness)
- Based on color (red, yellow black) – may have one, two or all three colors; classified by the least desirable color present
Adhesions
• Bands of scar tissue between/around
organs
• Abdominal cavity (may cause obstruction), between lungs and pleura
Contracture
• Contracture is part of normal wound healing
• Excessive contracture causes deformity d/t
shortening of muscle and/or scar tissue d/t
excessive scar formation – esp. near a joint