4 Flashcards
What is regeneration?
Replacement of dead / damaged cells w differentiated cells
What are labile cells? (+examples)
Cells which normal state is Active Cell Division (G1-M-G2)
Rapid prolif
E.g. epithelial / haematopoietic cells
What are stable cells? (+examples)
Cells which normal state is Resting State (G0)
Variable regen speed
E.g. hepatocytes / osteoblasts / fibroblasts
What are permanent cells? (+examples)
Cells which normal state is Resting State (G0)
Can’t divide (No regen)
E.g. Neurons / cardiac myocytes
Define unipotent cells
Cells that prod only one type of differentiated cell
Define multipotent cells
Cells that prod several types of differentiated cell
Define totipotent cells
Cells that can prod any type of differentiated cell
What are the 3 stages of Fibrous Repair?
- Cell Migration
- Angiogenesis
- ECM
What are the 3 types of cell involved in Cell Migration of fibrous repair?
- Inflamm cells (MAC / Neut: phagocytosis) (MAC / Lymphocytes: Chem. mediators)
- Endothelial cells (angiogenesis)
- Fibroblasts / Myofibroblasts (make collagen for ECM) (wound contraction)
What is the purpose of Angiogenesis in fibrous repair?
Delivers O2 and nutrients
What are are the 7 steps of Angiogenesis in fibrous repair?
- Endothelial prolif induced by proangiogenic GFs (VEGF)
- Blood vessels sprout new vessels
- Endothelial proteolysis of BM
- Endothelial cell migration (chemotaxis)
- Endothelial cell prolif
- Endothelial maturation + tubular remodelling
- Periendothelial cells recruitment
What is the purpose of the ECM in fibrous repair?
- Supports / anchors cells
- Cell communication
- Cell migration
- Separates tissue compartments
What are the 4 complications of fibrous repair?
- Insuff fibrosis (wound dehiscence / herniation / ulceration)
- Adhesion formation (blocks tubes)
- X function (cirrhosis)
- Overprod of scar tissue (tube block / joint contractures - constantly flexed joint)
What does granulation tissue consist of?
- Dev caps
- Fibroblasts / myofibroblasts
- Chronic inflamm cells
What is the function of granulation tissue?
- Fills gap + contracts n closes hole
2. Cap supply O2 / nutrients
How is Type 1 Collagen formed?
- Polypeptide alpha chains synth in ER of fibroblasts / myofibroblasts
- Enzymatic mod steps: (vit C dependant hydroxylation)
- Alpha chains align + crosslink –> procollagen triple helix
- Soluble procollagen secreted
- Procollagen cleaved –> Tropocollagen
- Tropocollagen polymerises –> microfibrils –> fibrils
- Fibrils –> fibres
- Crosslinking –> tensile strength
What causes Scurvy?
Lack of vit C (needed for vit C dependant hydroxylation) –> less crosslinking
What happens in Scurvy?
X heal wounds
More bleeding
Tooth loss
Old wound reopen
Is scurvy acquired or inherited?
Acquired
What causes Ehlers Danlos?
Defective procollagen –> tropocollagen
What happens in Ehlers Danlos?
Reduced tensile strength
Poor wound healing
Stretchy skin
Hypermobile joints
Is Ehlers Danlos acquired or inherited?
Inherited
What happens in OI?
Reduced bone tissue Brittle bones (banana leg) Blue sclerae (eye) Impaired hearing Dental abn
Is OI acquired or inherited?
Inherited
What causes Alport Syndrome
Abn Type 4 collagen
What happens in Alport Syndrome?
Impaired ear chochlea and eye lens function
Renal failure
Is Alport Syndrome acquired or inherited?
Inherited (X-linked so more in males)
What wounds heal by Primary Intention?
Incised wounds w. apposed (side by side) edges
Is there clot/ granulation tissue in Primary Intention?
Minimal
What happens to the epidermis in Primary Intention?
Regen
What happens to the dermis in Primary Intention?
Fibrous repair
What are the risks of Primary Intention?
Trapping an infection causing abcess
What wounds heal by Secondary Intention?
Infarcts / Ulcer / Abcess / Large wounds with unapposed edges
What happens to the large clot in Secondary Intention?
Dries and becomes scab
What happens to the epidermis in Secondary Intention?
Regen from base up
What are the differences between Primary and Secondary Intention Healing?
- Secondary prod more granulation tissue
- Secondary prod larger scar
- Secondary takes longer
What are the local factors affecting healing and repair?
- Size / location of wound
- Blood supply
- Infection
- Foreign material
- Radiation damage
What are the systemic factors affecting healing and repair?
- Age
- Diet defic (prot. / vit C)
- Diabetes / Obesity
- CV status
How does bone repair?
Callus formation
How does the CNS repair?
No regen capacity
Glial cells prolif –> Gliosis
How does the liver repair?
Acute damage –> regen
Chronic –> cirrhosis
How does Cardiac / Smooth Muscle repair?
Permanent tissue so replaced by scar
Why does skeletal muscle have limited regen ability?
Satellite cells
