Synapses Grade 11

Synapses- junctions or connections between two neurons.

1. A nerve impulse arrives at the end of the presynaptic membrane and causes CO2 to enter in the synaptic knob.
2. Vesicles containing neurotransmitters move towards the presynaptic membrane, fuse with it and release their content into the synaptic cleft.
3. ACH diffuses across the synaptic cleft and reaches the receptors at the post synaptic membrane.
4. ACH fuses with the post synaptic membrane.
5. The sodium channels open and the postsynaptic membrane is depolarised.

EPSP generated = signal is transmitted.

EPSP:
excitatory, stimulating, less than -70 mV (less negative due to the depolarisation)

IPSP: inhibitory postsynaptic potential.
Higher than -70 mV du to hyper-polarisation.