Synapses Flashcards
What is a synapse?
The point where the axon terminal of one neuron communicates with another, or the point where a neuron activates a muscle cell (neuromuscular junction)
How big is the synaptic cleft?
400nm wide
What is the role of the synaptic cleft?
Prevents electrical activity from jumping from one neuron to the next
How are neurotransmitters released?
- wave of depolarisation reaches axon terminal
- voltage gated calcium ion channels open
- calcium enters
- causes release of neurotransmitters from vesicles
What is the name of the neurotransmitter receptors?
Ligand-gated ion channels - open in response to a molecule binding into a receptor shape
What ions do post synaptic channels use?
Sodium channels or chloride channels
What happens if sodium channels are opened?
Sodium enters the cell, giving it a positive charge and making depolarisation more likely (stimulation/excitation)
What happens if chloride ion channels are opened?
Chloride enters the cell, giving a negative voltage and making depolarisation less likely (inhibition)
What is noradrenaline?
neurotransmitter used between postsynaptic neurons and target tissue in sympathetic nervous system
What is acetylcholine (ACh)?
neurotransmitter used between postsynaptic neurons and target organs in parasympathetic nervous system
What is glycine?
inhibitory neurotransmitter in CNS
What is glutamate?
Excitatory neurotransmitter in CNS
What is gamma amino butyric acid (GABA)?
Most common inhibitory neurotransmitter in CNS
Why do neurotransmitters need to be removed from synaptic cleft?
Prevent repeated transmission
How are neurotransmitter deactivated?
- enzymes destroy neurotransmitter
- reuptake of neurotransmitter into presynaptic neuron
