Healing & Repair Flashcards
Resolution
-initiating factor removed
-tissue undamaged (infection removed)/able to regenerate
Repair
-initiating factor still present
-tissue damaged & unable to regenerate
-replacement of damaged tissue by fibrous tissue
-collagen produced by fibroblasts
-REGENERATION CANNOT TAKE PLACE
When does cirrhosis arise?
By damaging liver repeatedly - architectural damage
Damage at the same time as regeneration
Describe lobar pneumonia
-affects a lobe of the lung
-alveoli filled w neutrophil polymorphs (acute inflammation) rather than air
-pneumocytes that line the alveoli can regenerate so the lung can be regenerated - the pneumocytes divide & reline the alveoli
Can lobar pneumonia resolve?
It can resolve
What type of lung damage occurs in covid?
Fibrosis
What are the 3 types of skin wounds?
-abrasions
-incised skin wounds
-tissue loss
What are abrasions?
Most supericial skin wounds, eg. road rash
How do abrasions heal?
-normal skin -> abrasion
-scab forms over surface
-epidermis grows out from adnexa - protected by scab
-thin confluent epidermis
-final epidermal regrowth
What are incised skin wounds?
-little damage to tissues on either side of cut
-2 sides of cut brought together accurately -> healing can proceed quickly
How do incised skin wounds heal?
-can be sutured
-incision
-exudation of fibrin
-weak fibrin join
-epidermal regrowth & collagen synthesis
-strong collagen join
How does a tissue loss injury heal?
-tissue loss injury/reason wound margins are not apposed requires another mechanism for repair
-skin edges cannot be brought together bc the cut is too deep to suture
-cells have to grow in
-fibroblasts grow in - epithelial cells grow across
-loss of tissue - granulation tissue forms - organisation - early fibrous scar - scar contraction
-phagocytosis to remove any debris
-granulation tissue to fill in defects & repair specialised tissue lost
-epithelial regeneration to cover the surface
-healing but bigger scar
-whiteness = collagen
Examples of repair
1) heart after myocardial infarction - myocardial fibrosis - collagenous scarring - won’t contract with the rest of the heart
2) brain after cerebral infarction - gliosis (fibrosis in the brain)
3) spinal cord after trauma
What is gliosis?
-fibrosis in brain
-glial cells instead of fibroblasts
-less dense scarring
What cells regenerate?
-hepatocytes
-pneuomocytes
-all blood cells
-gut epithelium
-skin epithelium
-osteocytes - help remodel bone fractures
What cells do not regenerate?
-myocardial cells
-neurones
What is organisation?
-process by which specialised tissues that have suffered damage undergo fibrous repair to form a scar
-necrotic cells are replaced with collagen
-repair by formation of mature fibrovascular connective tissue
-occurs by the production of granulation tissue & removal of dead tissue of phagocytosis
What are the processes involved in organisation/fibrous repair?
-phagocytosis of necrotic tissue
-angiogenesis (growth of new BVs by proliferation of endothelial cells)
-proliferation of fibroblasts & myofibroblasts -> allow collagen synthesis & wound contraction
-granulation tissue becomes less vascular to form a mature scar
-scar shrinks due to contraction of fibrils within the myofibroblasts
What is granulation tissue?
-GT is loops of capillaries supported by myofibroblasts
-actively contracts to reduce wound size
-GT fills in gap that is initially left by damage to tissue
-angiogenesis occurs within the granulation tissue & the new capillaries provide O2, nutrients, cells required to repair the damage
What happens if a fracture is not kept stable?
-repeated damage
-resolution cannot occur
-repair occurs instead of resolution
-fibrous tissue forms around the ends of bones -> bone ends become stiffer -> movement is reduced
What cells are found in granulation tissue?
Capillary endothelial cells
Fibroblasts
Myofibroblasts
Role of capillary endothelial cells in granulation tissue
Proliferate to form new capillaries - ANGIOGENESIS
Role of fibroblasts in granulation tissue
Secrete collagen & other components of the extracellular matrix
Role of myofibroblasts in granulation tissue
Fibroblasts with muscle filaments & attachments to adjacent cells - allows WOUND CONTRACTION
