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This movie shows how electric messages pass from one neuron to the next. As the message passes from neuron 2 to neuron 3, you can see a close-up of what happens at the gap between the two neurons.

You are watching: What is the space between two neurons

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Questions to Consider:What happens when the electric impulse reaches the end of a neuron?How does the message travel from one neuron to the next?Why are messages in the nervous system referred to as "electrochemical"? Tidbits:

Neurons are the communication cells of the brain and nervous system. They are specially suited to transmitting information from place to place throughout the body. Every neuron has three basic parts, though these may look somewhat different in different types of neurons. The cell body is the operational center of the neuron and contains the nucleus of the cell. Extending from the cell body are numerous branches called dendrites (dendro = tree), which receive incoming electric messages. The messages enter the dendrites, travel to the cell body, and then travel away from the cell body on another long, thin extension of the cell, called the axon. At the end of the axon, the message passes to the dendrite(s) of one or more other neurons, and it continues on its way as an electric impulse.

The combination of electric impulses (along the neuron) and chemical neurotransmitters (across the synapse) is why communication in the nervous system is called electrochemical.

Neurons do not actually touch each other. The axon of one neuron and the dendrite of the next are separated by a tiny gap called a synapse. Once an electric impulse reaches the end of an axon, it stimulates the release of chemicals called neurotransmitters into the gap in order to communicate with the next neuron in the pathway. These neurotransmitters fit into specific receptors on the surface of the receiving dendrite. When neurotransmitters trigger these receptors, ion channels open, starting an electric message in the receiving dendrite. The electric impulse races along the axon and across the synapse to the next neuron, where the process is repeated, keeping the message in motion.

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Several types of neurotransmitters are involved in specific pathways of the brain. Acetylcholine was the first neurotransmitter to be discovered. It is the chemical messenger that transmits messages from motor neurons to muscle cells, as well as from neuron to neuron in many of the brain"s pathways, especially those involved in learning and memory. Dopamine is thought to be involved in pathways that control movement and regulate emotional response. These pathways seem to be involved in schizophrenia and Parkinson"s disease. Stress and arousal produce norepinephrine, also called adrenaline. People with Alzheimer"s disease seem to have deficiencies in this neurotransmitter. Serotonin seems to control mood, consciousness, depression, and anxiety. Opioids, such as endorphins, act much the same way opium or morphine does to reduce pain. These neurotransmitters cause the runner"s high that many athletes report during times of elevated physical stress. Endorphins also seem to be released in the brain when a person eats chocolate. Several other chemicals act as neurotransmitters, including amino acids, hormones, and even some gases.