So now that we've gone through many of the structures found in the nervous system,
let's start talking about some of the functions.
Let's take a look at how we're going to generate nerve impulses.
In order for a nerve impulse to occur, excitable cells must communicate with each other
via action potentials or graded potentials.
Action potentials are going to allow for communication over both short and long distances
while graded potentials are going to only allow communication over short distances.
The production of both action potentials or graded potentials
are going to depend upon the existence of a resting membrane potential
as well as the existence of certain ion channels. Let's take a look at those channels.
There are four different types of channels that are found in the plasma membrane of neurons.
These channels are going to play a role in an action potential, a graded potential,
as well as establishing a resting membrane potential.
These channels include leakage channels, ligand-gated channels,
mechanically gated channels, and finally, voltage-gated channels.
The first of these channels is going to be the leakage channels.
Leakage channels such as potassium leakage channels found in the plasma membrane of neurons
are going to cause certain ions to leak from or into the cell.
These are going to randomly open at different times.
The second type of channel is going to be ligand-gated channels.
Ligand-gated channels are going to respond to a chemical stimulus such as a ligand binding to its receptor.
An example of ligand-gated channels are the acetylcholine binding to channels
which are gonna be necessary for nerve impulse to happen.
A third type of channel is the mechanically gated channels.
These are going to respond to a physical stimulus
so something physically moving them such as vibration or pressure.
In our ears, we have these mechanically gated channels
which actually respond to the vibrations from sound waves.
And finally, we have the voltage-gated channels.
We've seen these before in the muscular system.
These are going to respond to a change in the voltage across the membrane of the neuron.