Neurons – A whistle-stop Tour

Above: Structure of a typical neuron

http://en.wikipedia.org/wiki/ http://en.wikipedia.org/wiki/ http://www.google.co.nz/imgres?imgurl=http://cwx.prenhall.com/bookbind/pubbooks/morris5/medialib/images/F02_01.jpg&imgrefurl=http://http://www.google.co.nz/images?q=neuron&oe=utf-8&rls=org.mozilla http://www.google.co.nz/imgres?imgurl=http://www.faqs.org/photo-dict/photofiles/list/667/1077neuron.jpg

stained pyramidal neurons in cerebral cortex

http://www.youtube.com/watch?v=nR0m7rYZ_aY&feature=related

http://www.youtube.com/watch?v=gLxU80ge7vg&feature=player_embedded

By the end of this session you should be able to answer the following:

What is: An axon?What is a ‘spike’?

How many molecules are there in a neurotransmitter?

What does a dendrite do?Why is there a picture of a AA battery on this page?

What is in the synaptic cleft?Is synaptic transmission electrical, chemical, or both?

By the

Synaptic Transmission

Neurons communicate by chemical and electrical synapses when an electrical impulse is transmitted from one neuron to another along the AXON. This happens at a molecular level.

At synapses, the ends of axons (called axon terminals) nearly, but not actually touch the next neuron. Axon terminals contain many synaptic vesicules loaded with 2000 molecules of a specialised compound called a neurotransmitter. An electrical impulse called a ‘spike’ sends electrical impulses down the axon.Waiting for the ‘spike’ from the neurotransmitter is a receiver, called the dendrite. Between the axon terminal of one neuron and the dendrite is a tiny saltwater-filled gap called the synaptic cleft.

The brain can transmit between 400 to 1,200 spikes per second, but cannot go at the top rate for more than a few seconds. A typical ‘spike’ requires 70 millivolts , or one-twentieth of the power in an AA battery.(adapted from The Accidental Mind, D.J. Linden)

How Neurons Work