Week 2- Part 1- Introduction to neurotransmission. Flashcards
To understand how psychoactive drugs work, what do you need to understand?
What is neurotransmission?
Need to understand how neurotransmission works- these drugs often influence neurotransmission.
The transmission of signals between neurons- signals moving from one neuron to another depends on neurotransmission.
What are action potentials?
Where does neurotransmission happen?
Transmission of signals within neurons- action potentials are an electrical process.
Neurotransmission happens at synapses- within the nervous system.
Look at the picture in the docs- questions:
Does the presynaptic neuron form a connection with the postsynaptic neuron?
What does the presynaptic neuron’s axon (long projection) form a junction with?
What is the process of action potentials?
What is the lumpy end of the dendrite called?
What is neurotransmission all about?
Unrelated- but what does the refractory phase make it harder to do?
Yes.
With a dendrite on the postsynaptic neuron.
APs travel down the axon of the presynaptic neuron- then reach the buttons- signal may jump across the synapse- it may stimulate a signal in the postsynaptic neuron, stimulate another action potential.
The dendritic spine/knob.
How the signal gets across the gap.
Hard to cause it to fire again.
What happens when an AP reaches a synaptic button?
Where are the neurotransmitters released?
It triggers the release of neurotransmitter molecules.
Into the synapse- this leads to the transmission of a signal from one neuron to the next.
Neurotransmission:
What does synaptic transmission depend on?
What do these then do?
What is sir being vague about and why?
Depends on the release of neurotransmitter molecules from the pre-synaptic neuron.
Diffuse across the synapse and exert effects on the post-synaptic neuron.
Being vague about the effects- can take various forms- can be excitatory or inhibitory.
Continuation from neurotransmission:
What can a released neurotransmitter do to the postsynaptic neuron?
What can different NTs do?
Acts on it to either- make it more likely that the postsynaptic neuron will fire (because the NT has generated an excitatory postsynaptic potential)- or the release NT can make it less likely the postsynaptic neuron will fire because it has generated an inhibitory postsynaptic potential.
Different NTs do different things- some are excitatory (induce excitatory postsynaptic potentials) and others are inhibitory.
What is the most well-known excitatory NT?
What does another one include?
What is the most well-known inhibitory neurotransmitter?
Glutamate- most common excitatory neurotransmitter in the nervous system as well-
Dopamine.
GABA.
Receptors:
What do released NTs do?
What are receptors specific for?
What is a ligand?
Produce signals- in postsynaptic neurons- by binding to receptors- after they have diffused across the synapse.
Specific for a given NT- e.g. a dopamine receptor.
A molecule that binds to another.
Continuation from receptors:
What is an NT?
Why do we need a general word, why do we not stick to using neurotransmitter?
Ligand of its receptor- e.g. dopamine is a ligand of the dopamine receptor.
Because some drugs can mimic neurotransmitters and act as ligands.
Two main category of receptor:
What are ionotropic receptors associated with?
Are they slow or fast?
Associated with ligand-activated ion channels.
Fast- open and close fast when a neurotransmitter binds to them- let ions in or out of a cell.
Continuation from two main category of receptor:
What are metabotropic receptors associated with?
Are they slow or fast?
Associated with second messenger systems.
Slow- they do not directly open or close channels in a rapid way- they are associated with complicated second messenger systems that take time to get going.
Although receptors respond to specific NTs, what can happen?
There can be multiple receptor types for a given NT- e.g. there are several different types of dopamine receptor.
Example of ligand gated ionotropic receptors:
What is glutamate?
What happens when glutamate binds to its receptor?
What would you call it?
A sodium ion channel- it is normally closed.
Causes the ion channel to open and sodium ions rush in- sodium ions are positively charged which can make the inside of the neuron more positively charged- depolarised.
Excitatory- makes it more likely the neuron will fire- generating an excitatory postsynaptic potential.
Continuation from an example of ligand gated ionotropic receptors:
What is a GABA receptor?
What happens when GABA binds to a receptor?
What would you call it?
What two things do the complete opposite to each other by binding to their receptors?
Another ligand gated receptor- ion channel is normally closed.
Causes ion channels to open- negatively charged chloride ions rush inside the cell- make the inside of the cell more negatively charged relative to the outside- hyperpolarized.
Inhibitory- makes it less likely to fire- generating an inhibitory postsynaptic potential.
Glutamate + GABA.
What are the excitatory or inhibitory postsynaptic potentials?
What travels passively from their site of origination?
What also happens?
Regions of the neuron’s cell membrane that have either become depolarised or hyperpolarized.
EPSPs (depolarisation) + IPSPs (hyperpolarization)- they fade away as you get further away.
Decremental- they get smaller as they travel.
