The Brain, Neurons and Brain Chemistry
Crossing the Synaptic Gap
Most neurons in the brain communicate with each other by releasing chemical messengers called neurotransmitters. Neurotransmitters cross the gaps between neurons or between neurons and other cells, such as muscle, and match up with specific receptors. Chemical signaling between neurons allows different kinds of messages to be sent. For example, some chemical messengers stimulate neurons to fire, while other messengers make it harder for an electrical impulse to be generated in the receiving neuron. Since one neuron can share synapses with thousands of other neurons, the combined effects of different messages ultimately determine whether a signal will be triggered or not.
Many drugs interfere with communication between nerve cells. Some drugs act directly on neurons, neurotransmitters and receptors. Curare, for example, is a deadly poison used by South American Indians. It causes death from paralysis by blocking receptors on muscle cells. Since the receptors are blocked, the real chemical messenger for muscle contraction (acetylcholine) can no longer stimulate the muscles to contract.
Drugs also can interfere with communication between neurons in other ways, such as by preventing the manufacture or release of neurotransmitters, by causing excessive firing of neurons by stimulating massive releases of neurotransmitters, by mimicking the effects of chemical messengers, or by preventing the normal breakdown and recycling of chemical messengers.
Keywords: brain | chemical signaling | drugs | neuron | neuron firing | neurotransmitters | receptor site | receptors | synapse | synaptic gap
- Transmission electron microscopic image of the synaptic gap between two neurons. TEM image © Dennis Kunkel Microscopy, Inc.
- From the Brain Chemistry Teacher’s Guide activity, “Crossing the Synaptic Gap.” Brain Chemistry Teacher’s Guide © Baylor College of Medicine (ISBN: 978-1-888997-45-3) was supported, in part, by funds from the National Institutes of Health, Science Education Partnership Award grant number R25RR13454, and the NIH Blueprint for Neuroscience Research Science Education Award, National Institute on Drug Abuse and NIH Office of the Director, grant number 5R25DA033006.
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Funded by the following grant(s)
NIH Blueprint for Neuroscience Research Science Education Award, National Institute on Drug Abuse, and NIH Office of the Director
The Learning Brain: Interactive Inquiry for Teachers and Students
Grant Number: 5R25DA033006
Filling the Gaps: K-6 Science/Health Education
Grant Number: 5R25RR013454