How Synapse Works Flashcards
Most important ions if nervous system
Sodium na+
Potassium k+
Chloride cl-
What are ions
Atoms or groups of atoms which have gained or lost and electron and are this either positively or negatively charged
What do membranes have that let some things in but mostly they work to keep some things out
Ion channels that are topically closed
Resting. Potential
If the cell isn’t doing anything and it’s channels are closed
Resting potential is always in a state of
Imbalance- polarized
Resting Potential of the cell membrane is
Negatively charged
Imbalance of membrane
Polarization
Inside of cell is always
Negative
Outside of cell is always
Positive relative to the inside of the cell
The only way to send an impulse from that cell is to disrupt the
Polarized status
How to change the polarized state of cell membrane at rest
We need a spike in electrics voltage to disrupt things
The electric me voltage will be coming in from an axon to a dendrite
When that happens, the electricke signal MIGHT be string enough to disrupt resting potential
How disrupt RP
If the signal is sufficient to reach/breach the threshold
What does reach threshold mean
The degree of electricke charge must be string enough to change the permeability of the cell membrane
Why need to change permeability
Because the cell membrane is generally closed/at rest/ polarized
Once signal reach/beach threshold
Sodium/potassium pump go to work to disrupt the polarization
Disrupt polarization
Sodium rushes in
It wants a more negative environment inside
Disrupt polarization
Potassium rushes out
It Wants a more positive environment outside
Na in and k out will change…
The polarization (resting state of imbalance) between the inside and outside of cell
What does it’s all or nothing mean
The cell either fires or is doesn’t based on whether or not its threshold has been reached and breached
Most thresholds for firing requires a 5-10 mV change in polarity
Changing the polarization of a cell has two outcomes
Depolarization
Hyperpolarization
Which ever happens the process is quick, fluid, explosive
All gates open and close or … Not
Depolarization
Fire the impulse
Membrane is balanced
Hyper polarization
Do NOT fire the impulse
Keep imbalanced and closed
If depolarization occurs and sodium rushes in, disrupting. The rating potential/depolarizer state if the cell then…
The impulse will transmit down the axon of that cell body
Called action potential
Action potential occurs
At the moment a neuron send an impulse down its axon. It is also called a spike or impulse
The cell returns to its resting potential, due to the work of
Potassium channels
Is like the bouncer
Na/k pump to get na out and k back in–> refractory period
During polarization the rest if state if the cell membrane is
Negative
Polarization
Surge in voltage from an incoming impulse cause
Change in this resting potential (either more positive, or more negative. Than it’s resting negativity
From here two options
Depolarization steps
Some Neurotransmitters cause less negativity inside the cell this exciting the cell to fire a response
Initiates the action potential
Fire!
Aka excitatory post synaptic potential
Hyper polarization steps
Some Neurotransmitters cause less negativity inside the cell thus inhibiting any potential firing of a response
Inhibits the action potential
Do not fire
Aka inhibitory post synaptic potential
Purpose of inhibit
Basal ganglia either excite neurons to fire to create more necessary movements
Or inhibit because too much movement
T/f only shave one action potential occurring at a time
T
During that time the voltage gated ion channels are opening to allow na to rush in
And the they become inactive
Inactive is also known as
Absolute refractory period
Nothing else can happen then. No other action potential can take place
When k starts to rush out (no more na going in, it’s done) when k starts to rush out…
The ion channels start to depolarize back to being closed
During this k rush and efforts to depolarize membrane (go back to closed/resting potential)
You could stimulate another action potential
Only do this if the stimulus is white strong because you have not yet closed all of the ion channels. Called
Relative refractory period
