Neuroscience For Kids
The Synapse
Neurons have specialized projections calleddendrites and axons. Dendrites bring information to the cell body and axons take information away from the cell body.
Information from one neuron flows to another neuron across a synapse. The synapse contains a small gap separating neurons. The synapse consists of:
a presynaptic ending that containsneurotransmitters, mitochondria and other cell organelles
a postsynaptic ending that contains receptor sites for neurotransmitters
a synaptic cleft or space between the presynaptic and postsynaptic endings.
Hear IT!: Axon | Dendrite | Myelin |Neuron | Neurotransmitter | Soma |Synapse | Vesicle
Electrical Trigger for Neurotransmission
For communication between neurons to occur, an electrical impulse must travel down an axon to the synaptic terminal.
Neurotransmitter Mobilization and Release
At the synaptic terminal (the presynaptic ending), an electrical impulse will trigger the migration of vesicles (the red dots in the figure above) containing neurotransmitters toward the presynaptic membrane. The vesicle membrane will fuse with the presynaptic membrane releasing the neurotransmitters into the synaptic cleft.
Information from one neuron flows to another neuron across a synapse. The synapse contains a small gap separating neurons. The synapse consists of:
a presynaptic ending that containsneurotransmitters, mitochondria and other cell organelles
a postsynaptic ending that contains receptor sites for neurotransmitters
a synaptic cleft or space between the presynaptic and postsynaptic endings.
Hear IT!: Axon | Dendrite | Myelin |Neuron | Neurotransmitter | Soma |Synapse | VesicleElectrical Trigger for Neurotransmission
For communication between neurons to occur, an electrical impulse must travel down an axon to the synaptic terminal.
Neurotransmitter Mobilization and Release
At the synaptic terminal (the presynaptic ending), an electrical impulse will trigger the migration of vesicles (the red dots in the figure above) containing neurotransmitters toward the presynaptic membrane. The vesicle membrane will fuse with the presynaptic membrane releasing the neurotransmitters into the synaptic cleft.
Until recently, it was thought that a neuron produced and released only one type of neurotransmitter. This was called "Dale's Law." However, there is now evidence that neurons can contain and release more than one kind of neurotransmitter.
Diffusion of Neurotransmitters Across the Synaptic Cleft
The neurotransmitter molecules then diffuse across the synaptic cleft where they can bind with receptor sites on the postsynaptic ending to influence the electrical response in the postsynaptic neuron. In the figure on the right, the postsynaptic ending is a dendrite
(axodendritic synapse), but synapses can occur on axons (axoaxonic synapse) and cell bodies (axosomatic synapse).
When a neurotransmitter binds to a receptor on the postsynaptic side of the synapse, it changes the postsynaptic cell's excitability: it makes the postsynaptic cell either more or less likely to fire an action potential. If the number of excitatory postsynaptic events is large enough, they will add to cause an action potential in the postsynaptic cell and a continuation of the "message."
Many psychoactive drugs and neurotoxins can change the properties of neurotransmitter release, neurotransmitter reuptake and the availability of receptor binding sites.
When a neurotransmitter binds to a receptor on the postsynaptic side of the synapse, it changes the postsynaptic cell's excitability: it makes the postsynaptic cell either more or less likely to fire an action potential. If the number of excitatory postsynaptic events is large enough, they will add to cause an action potential in the postsynaptic cell and a continuation of the "message."
Many psychoactive drugs and neurotoxins can change the properties of neurotransmitter release, neurotransmitter reuptake and the availability of receptor binding sites.
Types of Synapses
Happy 116th Birthday to the word "SYNAPSE."
In 2013, the word "synapse" turned 116 years old. The word synapse was first used in a book called A Textbook of Physiology, part three: The Central Nervous System, by Michael Foster and assisted by Charles S. Sherrington, in 1897. It was probably Charles S. Sherrington who coined the term synapse. The word "synapse" is derived from the Greek words "syn" and "haptein" that mean "together" and "to clasp," respectively.
"You are your synapses. They are who you are."
--- Joseph LeDoux, 2002 (in Synaptic Self)
"You are your synapses. They are who you are."--- Joseph LeDoux, 2002 (in Synaptic Self)
See some synapses "Up Close and Personal".
Play the Interactive Word Search Game on the neuron and neurotransmitters.
Play the Interactive Word Search Game on the neuron and neurotransmitters.
Play an Outside Game to reinforce what you have learned about the synapse.
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