Which of the following statements are correct about synapse:
1. Nerve impulses speed up as they cross the synapse.
2. Synapses occur only between two neurons.
3. Destruction of the synaptic vesicles in #1 will prevent depolarization in neuron #2.
4. Neurotransmitters released from neuron #1 attach to the postsynaptic membrane of neuron #2.
5. Neurotransmitters diffuse across the synapse.
6. All neurotransmitters cause the depolarization of the postsynaptic membrane.
7. Neurotransmitters from neuron #1 are destroyed by enzymes.