Unit 1_Tissue Healing Flashcards
What is the attempt to restore the healing injured tissue to its optimal function?
Tissue healing
What are three components of tissue healing?
Fibronectin
Proteoglycans and elastin
Collagen
What type of tissue healing includes early structural support and tensile strength?
- Binds to fibrin (protein that assists with clotting)
- Opsonin (“harpoon” used to coat necrotic cells) to facilitate phagocytosis
- Chemotaxis (attraction of leukocytes/more fibronectin)
Fibronectin
What type of tissue healing bind to fibronectin and collagen for stability and elasticity? Hydrate tissue.
Proteoglycans and elastin
What type of tissue healing is known as a “glue producer”? It features structure/tensile strength.
- Most abundant protein in the body
- Flexibility to skin
- Rigidity to bone
- Elasticity of blood vessels
- Sensitive to exercise
Collagen
What are the phases of healing?
- Hemostasis and degeneration
- Inflammation
- Proliferation and migration
- Remodeling and maturation
What is the phase of healing that involves:
1. Stop bleeding
- Clump platelets together to form a clot
- Release bioactive proteins to summon inflammatory cells
- Summon growth factors to proliferation
- Degeneration
- Formation of hematoma, necrosis of dead cells, and start inflammatory response
- Migration of fibroblasts
Hemostasis and degeneration
What is the phase of healing that involves:
1. Endothelial cell proliferation
- Establish a vascular network for oxygen, nutrient transport
New capillaries form (angiogenesis)
- Wound initially fills with provisional wound matrix, which consists primarily of fibrin and fibronectin.
- As fibroblasts are drawn into the matrix, they synthesize new collagen, elastin, and proteoglycan molecules, which cross-link the collagen of the matrix and produce the initial scar - Damaged proteins in the matrix must be removed before the newly synthesized matrix components can be properly integrated.
Proliferation and migration
What is the phase of healing that involves:
1. Tissue contraction/contracture
- Shrinkage of wound –> myofibroblasts contract; Aids in wound closure
- Excessive shrinking can create a contracture (common in burns)
- Tissue regeneration
- Superficial skin wounds
- Epithelial cells are replaced, and structure/function is preserved
Remodeling and maturation
What are factors that affect tissue healing?
Growth factors
- Platelet-derived growth factor: activates fibroblasts/macrophages
- Fibroblast growth factor: stimulates angiogenesis
Nutrition
Other factors:
- Vascular supply
- Secondary infection
- Immune (over)reaction
- Age
- Co-morbidities (next two slides)
- Smoking
How do the following influence healing?
- CAD, Coronary artery disease; CHF, chronic heart failure; COPD, chronic obstructive pulmonary disease.
- Physiologic variables (e.g., age, growth factors, vascular sufficiency)
- The general health of the individual; immunocompetency; psychologic/emotional/spiritual well-being
- Presence of comorbidities (examples):
Diabetes mellitus
Decreased oxygen perfusion (e.g., COPD, CHF, CAD, pneumonia)
Hematologic disorders (e.g., neutropenia)
Cancer (local and systemic effects)
Alzheimer disease
Neurologic impairment
Co-morbidities
How do the following influence healing?
- Incontinence
- Immobility
- Tobacco, alcohol, caffeine, other substance use/abuse
- Nutrition
- Local or systemic infection; presence of foreign bodies
- Type of tissue
- Medical treatment (e.g., prednisone, chemotherapy, radiation therapy)
Co-morbidities
The extent to which cells can regenerate depends on what?
Type of cell
When a nerve is cut, the peripheral portion rapidly undergoes what?
myelin degeneration and axonal fragmentation
Within 24 hours of a cut, new axonal sprouts from the central stump are observed with the proliferation of what?
Schwann cells
Careful microsurgical approximation of the nerve may result in reinnervation, especially when?
in those with gaps less than 3 mm.
The most important factor in achieving successful nerve regeneration after repair is what?
The maintenance of the neurotubules (basement membrane and connective tissue endoneurium), along which the new axonal sprouts can pass
What phase of the bone healing process occurs as inflammatory cells arrive at the injured site accompanied by the vascular response and cellular proliferation?
Inflammatory phase
What phase of the bone healing process begins during the next few weeks and includes the formation of the soft callus seen on x-rays around 2 weeks after the injury, which is eventually replaced by a hard callus?
Reparative phase
What phase of the bone healing process occurs once the callus is sufficient to immobilize the fracture site, repair occurs between the fractured cortical and medullary bones when the fibrocartilaginous union (soft callus) is replaced by a fibroosseous union (hard callus)?
enchondral ossification
What phase of the bone healing process begins as no movement occurs at the fracture site and persists until the bone is returned to normal?
- During this phase, which may take months to years, the immature, disorganized woven bone is replaced with a mature organized lamellar bone.
- In the normal adult skeleton, approximately 10% to 30% of the bone is replaced or remodeled to replace microfractures from stress and maintain mineral balance.
- The time (and quality) for overall bone healing varies
Remodeling phase
Tendons and ligaments are dense bands of fibrous connective tissue composed of ___% water, ___% collagen, and ___% glycosaminoglycans.
This composition allows them to sustain ____ unidirectional tensile loads.
Tendons and ligaments are dense bands of fibrous connective tissue composed of 78% water, 20% collagen, and 2% glycosaminoglycans.
This composition allows them to sustain high unidirectional tensile loads.
The viscoelastic characteristics of these tissues make them capable of undergoing deformation under tensile or compressive force, yet still capable of returning to what?
their original state after the removal of the force
During the tendon injury and healing process, what begins immediately, followed by the inflammatory process, which begins during the first 72 hours (3 to 5 days) after injury or surgical intervention?
Hemostasis
