Synapses are specialized places between two nerve cells used for signal transmission between them. Neurotransmitters are chemicals released by neurons, that stimulate neighboring neurons and chemically pass electrical impulses to one another and throughout the nervous system.
[edit:](simplified) Structure of a synapse:
1. A presynaptic ending
2. a gap (synaptic cleft) between two neurons
3. A postsynaptic (receiving) ending
When a nerve signal reaches the end of an axon, it cannot go any further. So in most cases, the neuron triggers the release of a neurotransmitter (a chemical) that stimulates a new wave of electrical impulse in the next cell across the synapse. The first cell in the signal path is the presynaptic neuron. This one releases the neurotransmitter, while the postynaptic neuron (the second one) responds to it. The presynaptic neuron can synapse (communicate chemically) with center of the neuron, the axons ( a neuron's extensions) and dendrites ( smaller branched projections in a neuron).
Most synapses are chemical synapses, but a few cells use electrical synapses where electrical charged particles (ions) can diffuse directly from one cell to another, the disadvantage of this type of cell is that they cannot integrate information or make decisions. An advantage is that they can act faster.
http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f14-13a-b_synapses_c.jpg
15 Comments
andybesyOK. So the 'wires' are called axons, and when a neuron recieves an electrical impulse it transmits neurotransmitter chemicals across a synapse to receptors in another neuron?
Is the synapse the area between two neurons?
Are all neurons chemically connected, or do some have direct electrical connections via an axon?
mauz15>> ^andybesy:
OK. So the 'wires' are called axons, and when a neuron recieves an electrical impulse it transmits neurotransmitter chemicals across a synapse to receptors in another neuron?
Is the synapse the area between two neurons?
Are all neurons chemically connected, or do some have direct electrical connections via an axon?
Axons are just a part of the neuron
(simplified picture of a neuron)
http://www.morphonix.com/software/education/science/brain/game/specimens/images/neuron_parts.gif
The synapse is basically the sum of all components: The end of in the axon sending the electrical signal, the space between them ( called a synaptic cleft) and the receiving end of the other neuron.
http://anthropologynet.files.wordpress.com/2008/01/neuron-synapse.png
The neurons in the video communicate chemically via synapses. Axons are just extensions that each neuron has. Any given neuron can have numerous axons. At the end of each axon, there is an axon terminal this is the rounded ends you see in the video. The space between them is a synaptic cleft. Some neurons have electrical synapses instead. These are found in places where you need the fastest response but dont need to be able to interpret data or make decisions. Reflexes are an example. Electrical synapses are a minority though.
Sorry, I'll edit the description soon to try to make it more clear. I posted it in a rush.
turboj0esays...this reminds me of my physiological psychology class, I will be forwarding this to my professor!
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antUgh. *brief
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MrFiskWhy bother animating the synaptic vesicles when the neurotransmitter is apparently made of magic. Also, in my head, diffusion is a lot less springy. Epic *fail
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