Neurotransmitters
- Small signalling molecules that aid rapid communication.
- Can be excitatory and inhibitory.
- E.g., acetylcholine
Types of neurotransmitters
1. Glutamate
- Ionised form of glutamic acid
- Excitatory neurotransmitter- excites post synaptic neurone. s
- Stored in synaptic vesicles, tightly controlled levels in the brain.
- Most abundant in the human brain
- Cannot cross blood-brain barrier.
2. Gamma-aminobutyric acid (GABA)
- Major inhibitory neurotransmitter- causes inhibition of post synaptic neurone by
opening a chloride ion channel.
- Synthesised from glutamate by enzyme glutamate decarboxylase (GAD)
- Stored in vesicles.
- Doesn’t cross blood-brain barrier.
- Has anti-epileptic effects
- Effects of alcohol
Neurotransmitter removal
Neurotransmitters will keep the channels open until they are removed from synaptic cleft.
Neurotransmitters are rapidly removed via:
1. Diffuses away from synapses.
2. Re-uptake by presynaptic neuron
3. Enzymatic breakdown e.g., Acetylcholine- a enzyme called acetylcholinesterase gets
released from post synaptic membrane splits/breaks down acetylcholine into 2
molecules: acetate and choline which gets taken up by presynaptic neurone and
packaged into synaptic vesicles to be used again.
Types of Receptors
2 main types
1. Ionotropic
- Ion channels
- Quicker
- Direct (depolarisation)
AKA ligand gated ion channels, binding to receptor causes confirmational change.
E.g., glutamate opens cation channels and GABA opens anion channels.
2. Metabotropic
- GPCR’s
- Slow
- Indirect (signalling cascade)
- Can affect firing in number of different ways.
- Small signalling molecules that aid rapid communication.
- Can be excitatory and inhibitory.
- E.g., acetylcholine
Types of neurotransmitters
1. Glutamate
- Ionised form of glutamic acid
- Excitatory neurotransmitter- excites post synaptic neurone. s
- Stored in synaptic vesicles, tightly controlled levels in the brain.
- Most abundant in the human brain
- Cannot cross blood-brain barrier.
2. Gamma-aminobutyric acid (GABA)
- Major inhibitory neurotransmitter- causes inhibition of post synaptic neurone by
opening a chloride ion channel.
- Synthesised from glutamate by enzyme glutamate decarboxylase (GAD)
- Stored in vesicles.
- Doesn’t cross blood-brain barrier.
- Has anti-epileptic effects
- Effects of alcohol
Neurotransmitter removal
Neurotransmitters will keep the channels open until they are removed from synaptic cleft.
Neurotransmitters are rapidly removed via:
1. Diffuses away from synapses.
2. Re-uptake by presynaptic neuron
3. Enzymatic breakdown e.g., Acetylcholine- a enzyme called acetylcholinesterase gets
released from post synaptic membrane splits/breaks down acetylcholine into 2
molecules: acetate and choline which gets taken up by presynaptic neurone and
packaged into synaptic vesicles to be used again.
Types of Receptors
2 main types
1. Ionotropic
- Ion channels
- Quicker
- Direct (depolarisation)
AKA ligand gated ion channels, binding to receptor causes confirmational change.
E.g., glutamate opens cation channels and GABA opens anion channels.
2. Metabotropic
- GPCR’s
- Slow
- Indirect (signalling cascade)
- Can affect firing in number of different ways.
