The Action Potential! Flashcards
Astrocyte
A type of glial cell that does repair and scar formation
Oligodendrocytes
Form myelin in the CNS
Microglia
Macrophages of the CNS
Ependymal cells
Line the ventricles!
Gray vs white matter
Gray = cell bodies! White = myelinated axons!!
Myelin is high in lipids!
What is an axon hillock?
The junction between the soma and the axon!
Name for the body of an axon?
Soma
Graded potential?
What is an example
A graded potential is a local change in membrane potential!!!
Example = neuron firing!
Amplitude change with distance to stimulus? (Towards dendritic spine or closer to the soma)
High amplitude near stimulus!!
Passive Conduction!
No energy is used… current is just allowed to flow along a neuron.
What is the threshold potential in a cell?
When the Na+ Conductance is greater than K+ conductance!!!
This can generate an action potential.
Active Propagation…
The amplitude remains the same in an AP along the entire axon!!
Which channel opens faster/first?
Which channel stays open longer??
Na+ opens faster!
While K+ Stays open longer.
Speed of myelinated, unmyelaned, and larger/smaller axons?
Myelin = 225 mph (passive conduction)
Unmyelanated = 25mph
(Active conduction)
Larger axons are FASTER!
Which has a higher density of Na+/K+ channels? Nodes of ranvier or myelin?
Nodes of ranvier have a higher density!!
Myelin is low density and uses passive conduction!
What is absolute refractory due to?
Na+ channels being inactive!
What is relative refractory period due to?
Due to K+ channels being open!
