Chapter 8 Flashcards
(22 cards)
Refectory Period
Time period after an action potential in which Na+ gates may be inactive and the K+ channels may be open so that a second AP is impossible
What does it take to depolarize a cell?
For a depolarization to occur, Na+ influx must exceed K+ efflux
Local Current Flow
Movement of AP from region to neighboring region
What uses local current flow
All muscles use this process and a few neurons
Transmission Rate of AP
Dependent of axon diameter
-wider diameter has lower resistance
Where do AP start
AP usually begin at excitable tissue of axon hillock
What direction do AP go
AP are unidirectional due to the refractory period
What is the problem with this process? (AP)
Leakage of ions out of the cell during transmission
Neuroglial cells
Schwann Cells
Oligodendrocytes Cells
Schwann Cell
myelin forming cells of PNS
What do Schwann cells do
help prevent leakage of charge
Oligodendrocytes
myelin forming cells of the CNS
What do Oligodendrocytes do
Help prevent leakage of charge
Myelin Sheath
Cytoplasm wrapping around the axon
Node of Ranvier
breaks in between the axon that are not covered in myelin sheath
What is the difference between Schwann cells and oligodendrocyte
Oligodendrocytes can wrap wrap itself around several axons at a time while Schwann cells are one axon one wrap around.
Due to myelin insulation what is the outcome
There will be no channels under the myelin
Where is the only place that channels will be found
Node of Ranvier
Concentration of Ion
Any ions that get into the axon quickly move to the node where channels are present, no leakage will take place
Saltatory Conduction
AP propagation by “jumping” from node to node in myelinated fibers
How come muscles do not use Saltatory Conduction?
Need myelin and muscles do not have myelin
