Synapses

Question 1

What is a synapse?

Answer 1

Functional junction between 2 neurons or between a neuron and an effector

Question 2

What are the two types of synapses?

Answer 2

-Chemical
-Electrical

Question 3

What is an electrical synapse?

Answer 3

-Ionic current spreads to the next cell through the gap junctions
-Capable of synchronising groups of synapses

Question 4

What is the advantage of an electrical synapse?

Answer 4

-Faster
-Two-way transmission

Question 5

What is a chemical synapse?

Answer 5

One-way transmission of information from a presynaptic neuron to a postsynaptic neuron

Question 6

What happens at a chemical synapse?

Answer 6

1. Action potential reaches the end bulb and voltage-gated Ca²⁺ channels open
2. Ca²⁺ flows into the presynaptic neuron causing vesicles containing neurotransmitters to be released and move towards the synaptic left
3. The neurotransmitter is released by exocytosis diffuses across the synaptic cleft
4. The neurotransmitter binds to ligand-gated receptors on the post-synaptic neuron
5. This causes Na⁺ voltage-gated channels on the postsynaptic neuron to open and Na⁺ moves into the cell
6. If the threshold is reached, the postsynaptic neuron depolarises

Question 7

What do excitatory neurotransmitters do?

Answer 7

-Depolarise the post-synaptic neuron by making it more positive
-Makes action potential more likely

Question 8

What do inhibitory neurotransmitters do?

Answer 8

-Hyperpolarises the post-synaptic neuron by making it more negative
-Action potential less likely