Comprehension - L07 Flashcards
Do dendrites send or receive signals?
Dendrites receive information
What happens at terminal knobs?
This is where impulses are transmitted to the target cell
What does a membrane potential mean?
Difference in charge across a membrane
T or F
Inside of a cell is negative compared to the outside
True
What is the resting potential of a neuron?
-70mV
What two things contribute to the difference in charge across the membrane?
- Na+/K+ ATPase pumps 3 Na+ out per 2 K+ pumped in
- K+ ions are the charged substance w the most permeability in a resting nerve cell (Flow out through potassium leak channel)
What is an action potential?
- Changes in membrane potential after a stimulus
- Depolarization and repolarization
What happens during depolarization?
There is a decrease in electrical potential difference across a membrane
Sodium diffuses in
If above -50mV, voltage gated Na+ channels open
Increased permeability to Na+ ions results in a membrane potential of +40mV
Na+ channels spontaneously close
What happens during repolarization?
- Depolarization triggers opening of voltage-gated K+ channels
- Na+ gated channels close
- Membrane potential goes back to -80mV
- Large negative membrane potential causes the voltage gated potassium channels to close
What type of conduction occurs in unmyelinated axons?
Continuous conduction
What type of conduction occurs in myelinated axons?
Saltatory conduction
In, continuous conduction, The portion of the membrane that just experienced the action potential will be in a brief _____?
Refractory period, because sodium channels can’t reopen for a few milliseconds
In continuous conduction in unmyelinated neutrons, what happens to the flow of current?
The flow of current causes the membrane in the region just ahead to become depolarized
In saltatory conduction in myelinated axons, what prevents the passage of ions across the membrane?
Myelin
Where are most Na+ and K+ channels found?
In or near Nodes of Ravier
