Excitable cells Flashcards
Difference between AP and GP
AP: all or nothing, Very fast, only goes one way, cannot summate, only excitatory
GP: Variable size, Local signals, Can go in both directions, can be excitatory or inhibitory, can summate
What is the resting potential of a neuron
-65mV
what factors cause neurons to have a resting potential?
Selectively permeable membrane
Unequal distribution of charged molecules and ions
Physical forces ie. Diffusion and ES forces
What separates electrically charged ions
Neuronal membrane
What does the Nernst equation assume
There is selective permeability in the membrane for a specific ion
What is the equilibrium potential (Eion)
The membrane potential that would be achieved if the membrane was selectively permeable to that ion
electrostatic force exactly counteracts the diffusional force
What is the Nernst equation used for
To calculate equilibrium potential of an ion (Eion)
What is the Goldman equation used for?
Calculates reverse potential across a cell membrane
Takes into account all of the permeable ions
What are the three functions of neurons
Receive a signal
Integrate that information
Transmit a signal
How are APs coded
By Frequency
How are GPs coded
by size
When is a neuron said to be at rest
When it isnt generating impulses
What is the difference between a channel and a pump
Channel confers selectivity
Pump assists unequal charge distribution
What does the Na+/K+ pump do
Uses energy to produce and maintain a large K+ concertation gradient across neuronal membrane by pumping Na+ out and K+ in
How does an AP occur
Signal causes Na+ gates to open, Na+ rush into the cell and membrane potential becomes more positive (depolarisation)
