Synaptic Transmission

Question 1

Synaptic transmission

Answer 1

Once an action potential has reached the terminal buttons, it needs to be passed down onto the next neurone

• it needs to cross the synapse
• when the action potential reaches the end of the neurone, the presynaptic neurone releases neurotransmitters from the synaptic vessels into the synaptic gap

Question 2

What are neurotransmitters

Answer 2

• chemicals that diffuse across the synapse to the next neurone
• once the neurotransmitters have crossed the gap they bind to the post synaptic receptor sites
• the action potential then travels to the next neurone and the process continues.

Question 3

Re-uptake

Answer 3

• the neurotransmitter returns back to the presynaptic neurone where it is stored for later release
• the quicker this happens the shorter effects of the neurotransmitter
• enzymes can also turn off a neurotransmitter after they have stimulated the post synaptic neurone
• this makes the neurotransmitter ineffective

Question 4

Neurotransmitters can have an

EXCITATORY effect on the next neurone

Answer 4

Excitation- leads to the post synaptic neurone becoming positively charged and more likely to fire
Eg- Adrenaline

Question 5

Neurones can have an INHIBITORY effect on the next neurone

Answer 5

Inhibition- leads to the post synaptic neurone becoming negatively charged and less likely to fire
Eg- GABA

Question 6

Information can travel in ONE direction at a synapse

Answer 6

• neurones can only transmit information in one direction at the synapse
• The synaptic vessels containing the neurotransmitter are only released from the presynaptic membrane
• it is the binding of the neurotransmitter to the receptor which enables the signal/information to be passed/transmitted to the next neurone
• diffusion of the neurotransmitters mean they can only go from high to low concentration - can only travel from the presynaptic to the postsynaptic membrane