Synaptic transmission, i.e neurotransmitters, excitation / inhibition Flashcards
What is a synapse and why do these exist?
These are gaps within two neurons, they exist as neurons cannot make direct contact with each other, as this would break the transmission circuit.
What is the neuron before and the neuron after the synaptic gap known as?
Pre-synaptic neuron
Post-synaptic neuron
What is the method to the transmission of synapses? (4 steps)
- vesicles release neurotransmitters once the axon triggers this
- neurotransmitters then diffuse across the synaptic gap from area of high conc to area of low conc.
3.Each neurotransmitter has a specific shape + only fits into a specific receptor - Neurotransmitters then bind to a receptor on the dendrite of the next neuron.
What type of neurotransmitter is serotonin?
Inhibitory linked to inhibiting impulsive thoughts / messages.
What type of neurotransmitter is dopamine?
Excitatory linked to increasing activity of next neuron
When is an action potential triggered, and what does this means?
when a neuron gets enough excitation, meaning the excitation passes a threshold, sending the message of excitation along the cell.
What type of charge is the neuron inside/ outside when it’s at rest and why?
Inside - negatively charged
Outside - positively charged
This is because there’s a high conc. of positively charged sodium (Na) outside the neuron.
What happens when a neuron receives a “go” message from excitatory neurotransmitters and what happens to the gases/ ions inside?
The gates in the cell wall opens + allows sodium into the other cell.
This increases the conc. of positively charged sodium and potassium (K) inside the neuron.
Why does the neuron pass a “threshold” and what happens after, which is the process of action potential?
(4 steps to the process)
It passes when there is enough sodium in the neuron.
An action potential then travels down axon, jumping from node to node.
Vesicles in axon terminal then cause cell wall to rupture, releasing neurotransmitters into next synapse.
They then bind to the receptors on the dendrites and will either cause an excitatory effect / inhibiting effect.
This repeats if there is enough of an excitatory effect.
Define Excitation
in a neuron it means it has increased in electrical activity and is more likely to send an action potential
Define Inhibition
in a neuron it means it has decreased in its electrical activity and is less likely to start an action potential
Excitatory neurotransmitters causes what in the next neuron and inhibitory neurotransmitters causes what in the next neuron?
Excitatory - cause next neuron to increase in excitation
Inhibitory - cause next neuron to increase in inhibition.
How many input / output connections do neurons have?
10,000
What is the difference between what serotonin does in neurons and what dopamine does in neurons?
serotonin - closes gates and lets sodium drain post-synaptic neuron
dopamine - opens gates and increases sodium into post-synaptic neuron
define threshold
Minimum amount of charge needed for an action potential to occur
Define summation
The different neurotransmitters (inhibitory / exhibitory) adding up within a cell.
What is the process of summation? (2 steps)
- The inhibitory / excitatory neurotransmitters are summed within neuron
- if excitatory input outweighs inhibitory input, by a sign. difference, this will make the post-synaptic neuron trigger a new action potential.
Define temporal summation
same presynaptic neuron triggers the post-synaptic neuron repeatedly to make it fire.
Define spatial summation
Several presynaptic neurons trigger the post-synaptic neuron at a moderate level but together they add up to enough excitation to trigger the post-synaptic neuron to fire.
What is the car analogy with excitation / inhibition?
Excitation is like the accelerator whereas inhibition is like the brake.
