L2 Synaptic transmission and drugs Flashcards
Name the two types of messages transmitted by synaptic connections.
inhibitory and excitatory
What is Synaptic Transmission?
At the synapse a chemical (neurotransmitter) is released from one neuron, which passes across a small gap, to another neuron.
What is the gap in synaptic transmission called?
Synaptic cleft.
What are the chemical sacks called?
Synaptic vesicles
What is the process of neurotransmitter release called?
Exocytosis
What happens during exocytosis?
Synaptic vesicles fuse with the pre-synaptic membrane and release the neurotransmitter (chemical) to the synaptic cleft. The NT then attach/fuse to the post-synaptic receptors on the receiving neuron.
This can cause sodium channels to open and sodium to enter the neuron thus increasing the potential for it to reach the threshold of excitation and fire.
What ion channels are opened when the action potential travels down down the axon and gets the the pre-synaptic terminal?
Ca+ (calcium) channels.
When the AP reaches the pre-synaptic terminal what attaches to synaptic vesicles causing them to fuse and release the neurotransmitter?
calcium
What is needed for activation of the neurotransmitter?
calcium
What do neurotransmitters attach to on the post-synaptic membrane?
Receptors
What are receptors on the post-synaptic membrane?
membrane proteins which open ion channels.
What 2 ways are involved in neurotransmitter deactivation
Re-uptake (e.g. Dopamine, 5HT - seratonin)
Broken down
e.g. Acetylcholine becomes
Acetyl and Choline
What are the key, lock and door?
NT, binding site, channel
What are the 2 main classes of receptor for the brain?
Ionotropic and metabotropic receptors
What are the 2 main differences between ionotropic and metabotropic receptors?
- the ionotropic receptor binding channel and receptor are all in one structure – therefore, this can occur quickly as it all happens at once.
- Metabotropic receptor is separate from the channel so needs a second messenger system. Slower than ionotropic.
What is essential for the action potential to fire?
The threshold of excitation (-55mv) needs to be reached.
Define EPSP
Excitatory post-synaptic potential
What does an Excitatory synapse do?
Lets in positively charged ions (e.g. Na+) & makes the neuron more likely to fire.
i.e. Closer to the threshold of excitation.
Define IPSP
Inhibitory post-synaptic potential
What does an inhibitory synapse do?
Channel lets in -ve ions (e.g. Cl-) and makes the neuron less likely to fire.
Moves neuron away from threshold of excitation.
What is a synapse?
A structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell.
What does the axon hillock do?
Enables Integration of neural signals - A neuron can received lots of synaptic connections from other neurons (circa 10k). Some will be excitatory. They build up in the region known as the axon hillock – they are added together like a little computer. They are summated, averaged and then if it’s generally an excitation message and the threshold is reached, an AP is triggered.
What are agonist drugs?
Drugs which mimic and potentiate NT’s action (i.e. act on behalf of/activate)
What are antagonist drugs?
Drugs which block and reduce NT’s action
What type of drug is cocaine?
agonist
What type of drug is prozac and how does it work?
Agonist. Blocks re-uptake of serotonin.
What behaviours is the neurotransmitter dopamine associated with?
Rewards/motivation
Movement
What NT does cocaine act on?
Dopamine
What behaviours is the neurotransmitter 5HT (serotonin) associated with?
Depression, eating, sleep, aggression, inhibition
What NT do prozac and ecstacy act on?
5HT - serotonin
What 2 NTs do amphetamines act on?
Dopamine and noradrenaline
What behaviours is the neurotransmitter noradrenaline associated with?
Attention, vigilance, arousal, depression, feeding
What neurotransmitter dies of in Alzheimer’s Disease?
acetylcholine (Ach)
What behaviours are acetylcholine associated with
Memory, attention, sleep, muscle movement
What NT does GABA act on?
Noradrenaline
