- Motor neurons carry nerve impulses from the central nervous system to internal
organs, glands, and muscles.
Both types of neurons work together. Sensory neurons carry information about conditions
inside or outside the body to the central nervous system. The central nervous system pro-
cesses the information and sends message through motor neurons telling the body how to
respond to the information.
The Synapse
The place where the axon of one neuron meets the dendrite of another is called asynapse.
Synapses are also found between neurons and other type of cells, such as muscle cells. The
axon of the sending neuron doesn’t actually touch the dendrite of the receiving neuron.
There is a tiny gap between them, as shown inFigure20.3.
Figure 20.3: This diagram shows a synapse between neurons; when a nerve impulse arrives
at the tip of the axon, neurotransmitters are released and travel to the receiving dendrite,
carrying the nerve impulse from one neuron to the next. ( 11 )
When a nerve impulse reaches the tip of an axon, the axon releases chemicals calledneu-
rotransmitters. These chemicals travel across the gap between the axon and the dendrite
of the next neuron. They bind to the membrane of the dendrite. This triggers a nerve
impulse in the receiving neuron. Did you ever watch a relay race? After the first runner
races, she passes the baton to the next runner, who takes over. Neurons are a little like relay
runners. Instead of a baton, they pass neurotransmitters to the next neuron. Examples of
neurotransmitters include serotonin, dopamine, and adrenaline.
Youcanwatchananimationof nerveimpulsesand neurotransmittersat:http://www.mind.
ilstu.edu/curriculum/neurons_intro/neurons_intro.php