Peripheral Nerves Flashcards
How can one input lead to 2 specific outputs?
Remeber PNS
- If sensory neuron synapses with a inhibitory interneuron
(on its way to the motor neuron)
Which part of the spinal cord has a root ganglion?
dorsal or ventral?
Dorsal!
What is the function of the perineurium/endoneurium/epineurium?
+ what they are
- Sheath of connective tissue
- Gives structural rigidity and flexibility
Why does the PNS require a sheath of connective tissue - and the CNS doesnt?
- PNS moves a lot so it needs encasing
- CNS doesnt move
What does a schwann cell do?
Surroundes every axon in the PNS
What is this?
What is a fascicle?
- Bundle of axons wrapped in perineurium
What is this?
What is this?
What is this?
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What is this?
What is the process of myelination?
- Glial cell wraps around axon
- Cytoplasm squeezed out as sheath forms
- Myelin sheath acts as insulation
What do we call the gaps in the myelin?
Nodes
How does myelination allow for fast axonal conduction?
- Allows ‘jumping conduction’ from node to node
How can we increase the speed of conduction?
- Increase internodal distance
- No myelin but, thicker axon
What is this?
What is this?
What is this?
What is this?
What is this?
How does myelin affect the speed signals travel?
- Myelin insulates the cell
- Which allows for more charge to be conserved (And not leave) at internodes
- The myelin-less nodes then will experience sufficient energy to open up the Na gates
- The Na gates speed up signal transfer (as it is via diffusion)
How do nerves regenerate after an axon is damaged?
- Schwann cells repair while SC and macrophages clean up
- Muscle accepts regenerated axon, protein synthesis occurs and axon regenerated
- Regeneration may fail if axons are unable to regenerated &muscle prevent reinnervation
