Tissue injury and repair Flashcards
What three outcomes can injury to tissue lead to?
adaptation
reversible injury
irreversible injury and cell death
What is homeostasis ?
how variables are regulated so that internal conditions are kept stable
What does increased demand or stimulation lead to ?
hypertrophy or hyperplasia
What does decreased nutrients or stimulation lead to ?
atrophy
What does chronic irritation lead to ?
metaplasia
What are the causes of cellular injury?
- hypoxia
- physical agents
- chemical agents
- infectious agents
- immunologic reactions
- genetic derangements
- nutritional imbalance
What are the mechanisms of cellular injury ?
- ATP depletion
- mitochondrial damage
- increased intracellular calcium
- oxidative stress
- membrane damage
- DNA and protein damage
What does tissue regeneration require ?
viable stem cells and intact connective tissue
tissues with high proliferative capacity
What are examples of true regeneration ?
epithelium following superficial skin injury
bone following fracture
Healing can be done by three things…
repair (normal structure)
scarring (scar formation)
fibrosis (tissue scar )
persistent damage leads to chronic inflammation which would lead to …
fibrosis
What happens in fibro-proliferation response?
- deposition of collagen and ECM components (scar)
- ‘patches’ tissue
What is the sequence of healing ?
- inflammation
- angiogenesis
- migration and proliferation of parenchymal cells and fibroblasts
- scar formation
- connective tissue remodelling
Give examples of local factors affecting wound healing?
size
location (how vascular it is )
type (infectious/necrotic/traumatic)
infections, mechanical forces, foreign bodies delay healing
Give examples of systemic factors that affect healing .
nutritional status
metabolic status ( eg. diabetes)
circulatory/ vascular status
hormones ( glucocorticoids)
