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

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 a mammoth achievement of science. In order to look at synapses in detail, it is necessary to understand the structure and components of the cell and those it attaches to. Figure 1 shows a neuron, as indicated on the diagram; the dendrites are the receivers of information for that cell. The dendrites receive neurotransmitters from the synapses that connect to it and if enough are present, an action potential is caused which then travels down the axon to the terminal buttons also known as synapses. There are electrical and chemical synapses in the body although the vast majority are chemical. Electrical synapses are located in the retina and in some invertebrates such as crayfish (Pocock, G. & Richards, C, D 2004), since chemical transmissions are more prevalent, these will be covered below.

Figure 1: Neuron, http://www.answers.com/topic/neuron

A synapse forms a junction between which nerve impulses and electricity in some cases pass through a gap (of approximately twenty nanometres) known as the synaptic cleft from the axon terminal to the target cell. This junction consists of the presynaptic neuron being linked to the post

References: Carlson, N, R. (2004) Physiology Of Behaviour, 8th edition, Boston: Pearson Education Inc Iworks contributors. Synapse. Iworks. Retrieved march 16, 2006 from http://www.iworx.com/company2/WebToolsCD/Illustrations/synapse/synapse_web2.jpg Pocock, G. & Richards, C, D. (2004) Human Physiology The Basis Of Medicine, 2nd edition, Oxford: Oxford University Press Rosenzweig, M, R. Breedlove, S, M. & Watson, N, V. (2005) Biological Psychology An Introduction To Behavioural and Cognitive Neuroscience, 4th edition, Massachusetts: Sinaur Associates Wikipedia contributors (2006). Adenosine triphosphate. Wikipedia, The Free Encyclopedia. Retrieved 00:52, March 17, 2006 from http://en.wikipedia.org/w/index.php?title=Adenosine_triphosphate&oldid=43801949. Wikipedia contributors (2006). Synaptic vesicle. Wikipedia, The Free Encyclopedia. Retrieved 00:55, March 17, 2006 from http://en.wikipedia.org/w/index.php?title=Synaptic_vesicle&oldid=42637515. Wikipedia contributors (2006). Synaptic vesicle. Wikipedia, The Free Encyclopedia. Retrieved 01:08, March 17, 2006 from http://en.wikipedia.org/w/index.php?title=Synaptic_vesicle&oldid=42637515. Wikipedia contributors (2006). Neuron. Wikipedia, The Free Encyclopedia. Retrieved 13:52, March 17, 2006 from http://en.wikipedia.org/w/index.php?title=Neuron&oldid=44014303.