L12: Degeneration And Regeneration Of Nerves Flashcards
In the somatic nervous system what is the effector
Skeletal muscle
In the autonomic nervous system what is the effector
Cardiac muscle
Smooth muscle
Secretory glands
What is the Seddons classification
The 3 classes of responses expected from a neurone after damage
What is seddons 3 classes
Neuropoxia
Axonotomesis
Neurotmesis
What are the 3 layers of the axons
Endoneurium
Perineurium
Epinineurim
Which layer is the most superficial
Epiniurium
Which layer is the deepest
Enoneurium
What is neuropraxia
When the myelination of a neurone is disturbed
Is the loss of function in neuropaxia permanent
No it is temporary and function is normal after recovery
What is axonotmesis
When axons with myelin sheath is damaged
In axonotmesis does the 3 layers of the neurone remain intact
Yes
What is axonotmesis a result of
Severe crush
What happens during axonotmesis
Wallerian degeneration
What is neurotmesis
When the entire nerve is completely injured
What layers become damaged in neurotmesis
Axon and connective tissue
Does recovery occur in neurotmesis
Not fully if the damage is close to the cell body
From the seddons classification what is the most sever class of injury
Neurotmesis
Which factors are released when there is a damaged neurone
Myelin forming cells
Astrocytes
Microglia
What are myelin forming cells
Oligodendrocytes
Schwann cells
What do oligodendrocytes do
Myelinate up to 250 axons at the same time
What do Schwann cells do
Demyelination of one axon
What do astrocytes do
Create environment for neurone
What do microglia do
They are activated and start to digest material around by contracting around injury
What happens to a damaged neurones minutes after injury
Neurone stops conduction AP
Two ends will be exposed and leak into extracellular fluid
Two ends cut and seal and swell apart
What happens to a damaged neurone hours after
Synaptic terminal degenerates by macrophages and phagocytosis
Astrogliua surrounf the synaptic terminal for further degeneration
What happens to a damaged neurone days after
Cell body undergo chromatolysis
Volume of cell body increases due to protein production
Nucleus is pushed to the side of the body
Injured nerve forms a neuroma
What is chromatolysis
Breaking up of a cell in a colourful way
What happens to a damaged neurone weeks after
Distal stump of axon undergo wallerian degeneration and is removed by phagocytosis
Tissues are preserved
Regenerating axons form many sprouts into Schwann cells
Which nervous system is oligodendrocytes found in
Central nervous system
Which nervous system is Schwann cells found in
Peripheral nervous system (PNS)
