Describe how synapses work in the context of the nervous system.

Synapses are really important in the transmission of information signals through the nervous system. They connect two (or more) neurons, aiding the passage of information through the system. This passage of information involves the conversion of an electrical signal to a chemical one, and then back again. An electrical impulse (action potential) travels along an axon, untill it reaches the synaptic bulb, found at the nerve ending. This process depolarises the membrane of the nerve, which triggers the opening of voltage-gated calcium ion channels on the nerve membrane. This causes Calcium to flow into the nerve. This influx of Calcium causes the release of vesicles containing neurotransmitters such as Acetylcholine into the synaptic cleft. They diffuse across the space and bind to receptors on the target neuron. This binding causes the generation of an action potential in the second neuron, and ensures the signal passes on through the nervous system.