Detail the Components of a Synapse and Describe the Sequence of Events at a Synapse When Information Is Transmitted.

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Synapses are an essential and fascinating part of communication within the central nervous system. They are the transmitters of chemical and electrical messages that cause us to see, feel, move and much more. The brain consists of around 100 billion neurons, each of which has around 7,000 synaptic connections to other neurons. It has been estimated that a three year old child has 1,000 trillion synapses, and since number of synapses decreases with age until it stabilises in adulthood it is estimated the average adult has between 100 and 500 trillion synapses.(Wikipedia contributors (2006). When looking at the brain in this context, you can appreciate the sheer complexity of it and that looking at the functioning of a single synapse is…show more content…
Figure 2 shows most of these parts as described above. (Rosenzweig, M, R. Breedlove, S, M. & Watson, N, V. 2005) Figure 2: http://www.iworx.com/company2/WebToolsCD/Illustrations/synapse/synapse_web2.jpg

Electrical synapses work faster than chemical synapses with almost no time delay involved. This is because in electrical synapses, the synaptic cleft is only between 2 and 4 nanometres as compared to the 20 to 40 nanometre cleft in a chemical synapse. Also the presynaptic and postsynaptic membranes of the electrical synapses have larger channels fixed in them allowing ions to travel directly from one cell to the other without having to pass through the synaptic cleft, and the electrical current can travel between presynaptic and postsynaptic membranes with practically no time delay. This is opposed to the delay of around a millisecond caused by passage through the synaptic cleft in a chemical synapse, which although is very quick, for neurons is relatively slow. (Rosenzweig, M, R. Breedlove, S, M. & Watson, N, V. 2005)

In order for information to be transmitted from the presynaptic neuron to the postsynaptic cell, a series of events needs to take place. This begins when a nerve impulse i.e the result of an action potential reaches the presynaptic axon terminal or synaptic knob. This results in the synaptic knob becoming depolarized, that is, more negatively charged thus activating the voltage-gated calcium channels into opening. Positively

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