Explain the series of events at a synapse between 2 neurons.

An impulse travels along the pre-synaptic neurone, and when it reaches the axon ending it stimulates calcium channles to open on the pre-synaptic membrane. This allows calcium ions to rush into the neurone causing vesicles of neurotransmitter to move to the pre-synaptic membrane and bind to it. The contents of the vesicles are sent out into the space inbetween the neaurones (synaptic cleft) via a process called exocytosis. The neurotransmitter then binds to receptors on the post-synpatic membrane, opening sodium channels which allows sodium ions to rush in and cause a new impulse to be created in the post-synaptic neurone. Enzymes are then released to break down the neurotransmitters. This shuts the sodium channels, and the broken down neurotransmitters are taken bakc up into the pre-synaptic membrane to be put back together.