3. repolarizing a. The gate must complete the cycle over a given time period. Movement of impulse 1. Post synaptic membrane contains chemically gated selective ion channels 1. Each gate has a receptor which is keyed to a specific neural transmitter.
Transmitter binding causes the channel to open.
Rapid degradation or release is required to limit stimulation B. Steps in transmission across the synaptic cleft 1. Binding of transmitter to receptor opens selective channels and flow of ions follow appropriate gradients . Degradation of neurotransmitter causes channels to close. Movement of ions across the membrane results in transitory changes in the membrane potential. Direction of the impulse across the synapse is due to 1.