W3 - Tissue Healing Flashcards
What is a sprain
Injury to a ligament
What is a strain
Injury to a tendon or muscle
Name four factors that caused tissue damage
Injury: physical, thermal, electrical, chemical
Infection: viruses, bacteria, fungi
Infarction: myocardial infarct
Immune reactions: foreign protein hypersensitivity and autoimmunity
Name three types of tissue healing
Resolution
Tissue regeneration
Connective tissue repair (replacement)
What happens in resolution?
Occurs in acute inflammatory responses to minor injuries
Damaged tissue is restored to the state it was before the injury occurred
Most commonly occurs in epithelial tissue
Name an example of a resolution tissue healing
A mild insect bite
What happens in tissue regeneration?
Lost parenchymal cells are replaced by the division of surviving parenchymal cells
Before regeneration can occur all necrotic cells must be removed which involves an acute inflammatory response
What factors influence if tissue regeneration occurs?
The regenerative capacity of involved cells
The number of surviving viable cells
The presence of connective tissue framework that will provide a base for restoring normal tissue for structure
What cells have the ability to regenerate?
Labile cells = constant turnover i.e. skin cells
Stable cells = usually stop growing once growth stops and require requires a supportive framework if damaged i.e. liver kidney and lungs
What happens in the bleeding phase of connective tissue repair?
Occurs straight after the injury and is short-lived
If damage occurs to vascular tissue breathing will last longer i.e. muscle
Of tissues such as ligaments bleed less in volume and duration
Average time is 4 to 6 hours
What happened in the inflammatory phase of connective tissue healing?
Occurs within the first few hours of injury and peaks in one to 3 days
Resolved in a few weeks
Changes in blood flow occur such as odemea, leukocytes emigration, phagocytosis and lymphatic drainage
What stage happens after the inflammatory phase of connective tissue healing?
The proliferative phase
What happens in the proliferative phase of connective tissue healing?
Occurs 24 to 48 hours after injury
Can take up to a few weeks or months
Fibroblasts , macrophages and blood vessel proliferate to form granulation tissue
What two fundamental processes happen in the proliferative phase of connective tissue healing?
- Angiogenesis occurs with development of capillary buds
- Collagen synthesis occurs to produce type three collagen.
What phase happens after the proliferative phase of connective tissue healing?
The remodelling/maturation phase
What happens in the remodelling/maturation phase of connective tissue healing
Continuous remodelling of scar tissue: fibroblasts synthesis to produce type one collagen and simultaneous lysis by collagenase enzymes
What are the complications of tissue repair?
Infection
Ulceration
Dehiscence
Adhesions
Keloid development
What cells cannot undergo tissue regeneration
Fixed non-dividing cells such as nerves, muscles and cardiac as they cannot undergo mitosis
