Chapter 4 - Repair: Recovery from Injury Flashcards
Healing = repair
Can occur by either regeneration or scarring; usually both processes occur in any given injury
- Regeneration
- Scarring
Regeneration
Complete or nearly complete restoration of normal anatomy and function my regrowth of formal functional tissue (parenchyma) and supporting tissue (stroma)
- Labile cells
- Stable cell
- Permanent cells
Labile cell
Short-lived cells with stem cells that easily and continuously regenerate
- Epithelium: epidermis, G.I. lining, respiratory whining
Stable cell
Long-lived styles with stem cells that highly regenerate after injury
- Glandular organ: liver, kidney
- Fibrous connective tissue
- Bone and cartilage
- Blood vessels
Permanent cells
- Long live cells
- Essentially no stem cells, do not regenerate
- They are for healing and repair is by scarring only
- Neurons, cardiac muscle, skeletal muscle
Scarring
Fibrous repair (replacement by fibrous connective tissue)
- Granulation tissue
- Collagen accumulation
- Injury
Granulation tissue
Early stage, as early as 24 hours after injury
- Consist of migrating and proliferating myofibroblasts and small blood vessel’s
• Fibroblasts produce collagen
• Blood vessels provide nutrients for the new tissue - Organization
- Angiogenesis
Organization
Process of replacing necrotic material, blood caught or exudate with fibrous tissue
Angiogenesis
(Neovascularization) The growth of new blood vessels into organizing tissue
Collagen accumulation
Later stage
- Collagen is a long fibrillar protein; gives strength to the healing wound
- Cicatrix: mature scar
Injury
- Mild injury: regeneration and no scarring
- Extensive injury: regeneration and scarring
- Permanent injury: scarring only
Healing by first intention
- Healing of a clean wound, smooth edges that are close together
- Heals quickly, leaving a small scar
- Example: surgical wound with closed sutures
Healing by second intention
- Healing of gaping wind or one complicated by infection or foreign material
- Healing: slow, leaving a more extensive scar
- Example: large laceration in a motor accident
Aberrant healing
Wound repair creates a problem rather than solving one
- Keloids
- Pyogenic granuloma
- Adhesion
- Contracture, stenosis, constrictions
- Dehiscence
Keloids
Abnormally large bulging scars – it over heals
- Common around face and upper body
- Genetic predisposition: African heritage
- Tend to recur when removed
Pyogenic granuloma
Persistent granulation tissue – repair process halted in most vascular stage
- Example: healing umbilicus in newborns appear as a flashy bleeding nodule
Adhesions
Scar tissue on surfaces of body cavities due to myofibroblasts
- Abdominal adhesions between loops of bowel – term for non-viscera too
- Pleural adhesions between lung and chest wall
Contractures, stenosis, constrictions
Scar tends to contract as it matures due to myofibroblasts
- Extensive contraction of scar tissue may interfere with normal function:
• Joint and muscle immobility
• Narrowing of hollow organs
Dehiscense
Previously closed when that bursts open
- Occurs and partially healed wound
- Maybe associated with:
• Poor collagen production (poor nutrition/blood supply; congenital)
• Delayed wound healing due to infection or foreign bodies
Factors that help inflammatory responses and wound healing
- Nutrition
- Good blood supply
- Primary union
Good nutrition
Very important
- High protein diet: rapid healing
- Adequate vitamin C: needed for good collagen formation
Good blood supply
Necessary for inflammation and repair
Primary union
Clean, smooth surgical wound edges; decreased scarring (first intention)
Factors that hinder inflammatory responses and wound healing
- Secondary union
- Wound infection
- Foreign bodies
- Leukopenia
- Blood in tissue
- Metabolic derangement
- Corticosteroid
Secondary union
Ragged wound edges; heal slower, increased scarring (second intention)
Wound infection
Bacteria slows healing stage
Foreign bodies
Interfere with healing
Leukopenia
Decreased number of leukocytes;
- Decreased inflammatory response
- More susceptible to infection
Blood in tissue
Encourages bacterial growth; slows repair process
Metabolic derangements
Diabetes interfere with proper function of inflammatory and reparative cells
Corticosteroids
Cortisone
- Decreased inflammation: good
- Slow healing: bad
