Synapses Flashcards
What is a synapse?
Functional junction between 2 neurons or between a neuron and an effector
What are the two types of synapses?
-Chemical
-Electrical
What is an electrical synapse?
-Ionic current spreads to the next cell through the gap junctions
-Capable of synchronising groups of synapses
What is the advantage of an electrical synapse?
-Faster
-Two-way transmission
What is a chemical synapse?
One-way transmission of information from a presynaptic neuron to a postsynaptic neuron
What happens at a chemical synapse?
- Action potential reaches the end bulb and voltage-gated Ca²⁺ channels open
- Ca²⁺ flows into the presynaptic neuron causing vesicles containing neurotransmitters to be released and move towards the synaptic left
- The neurotransmitter is released by exocytosis diffuses across the synaptic cleft
- The neurotransmitter binds to ligand-gated receptors on the post-synaptic neuron
- This causes Na⁺ voltage-gated channels on the postsynaptic neuron to open and Na⁺ moves into the cell
- If the threshold is reached, the postsynaptic neuron depolarises
What do excitatory neurotransmitters do?
-Depolarise the post-synaptic neuron by making it more positive
-Makes action potential more likely
What do inhibitory neurotransmitters do?
-Hyperpolarises the post-synaptic neuron by making it more negative
-Action potential less likely