Synaptic transmission

Question 1

Describe synaptic transmission (6)

Answer 1

1) Begins in the presynaptic neutron, action potentials are sent down axons to the pre synaptic terminal button

2) Neurotransmitters which are stored in vesicles which are only located in the presynaptic neuron are released into the synaptic cleft

3) The neurotransmitters diffuse across the synapse, from a high to low concentration, and bind to their specific receptors which are only found on the post synaptic neuron

4) Once enough neurotransmitters bind to their receptor sites on the post synaptic neuron there are two outcomes

5) The next neuron is ready to fire an impulse depending on whether the neurotransmitter had an excitatory and inhibitory effect

6) The neurotransmitters are recycled back to the vesicles in the presynaptic neuron in a process called reuptake

Question 2

Excitatory neurotransmitter (3)

Answer 2

e.g. adrenaline

1) When an excitatory neurotransmitter binds to the post synaptic neuron, the post synaptic cell becomes positively charged.

2) This makes the post synaptic neuron more likely to fire so an impulse can travel down the axon.

3) This increases brain activity in the CNS.

Question 3

Inhibitory neurotransmitter (3)

Answer 3

e.g. serotonin

1) When an inhibitory neurotransmitter binds to the post synaptic, the post synaptic cell becomes positively charged.

2) This makes the post synaptic neuron less likely to fire an impulse down the axon

3) Thus decreases brain activity in the CNS

Question 4

Summation (3)

Answer 4

1) When inhibitory and excitatory influences are added together

2) If the overall effect is excitatory the impulse will fire an impulse dow. the post synaptic neuron

3) If the overall effect is inhibitory it reduces the likelihood the neuron will fir an impulse down the post synaptic neuron