Summary
The junction where one neuron communicates with another or with a muscle cell.
In depth
At chemical synapses the presynaptic terminal, synaptic cleft (about 20 nm) and postsynaptic membrane form a one-way junction. Electrical synapses (gap junctions) are faster and bidirectional.
The synaptic cleft is crossed by diffusing transmitters in under a millisecond. Synaptic strength can change. Neuromuscular junction is the best studied synapse.
Remember: transmission is generally one-way.
A typical neuron has 1000 to 10,000 synapses, giving a total of about 100 trillion in the human brain. The active zone in the terminal holds vesicles, with about 1 to 10 released per action potential. Electrical synapses use gap junctions of connexins and are fast and bidirectional, found in the heart, retina and in synchronising neurons. Chemical synapses are slower (about 0.5 ms delay) but allow amplification, inhibition and plasticity. Synaptic types: axodendritic, axosomatic and axoaxonic.
Tripartite synapse: astrocytes surround synapses and regulate neurotransmitter levels. Synapses are targets of drugs and toxins: botulinum, curare, nicotine, SSRIs and benzodiazepines. Charles Sherrington coined the word synapse in 1897.
Example: synapse number in the cortex peaks in early childhood and is pruned during adolescence.
Frequently asked questions
What is Synapse?
The junction where one neuron communicates with another or with a muscle cell.
Which area of biology covers Synapse, and how advanced is it?
Synapse is one of the 54 topics in Neuroscience. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Synaptic Transmission, Neurotransmitters, Neuropharmacology.
Can you give an example of Synapse?
The neuromuscular junction uses acetylcholine to trigger muscle contraction.
What should I learn before Synapse?
Synapse is a Beginner topic, so no earlier topic is required. Other Beginner topics in Neuroscience that pair well with it include Nervous System, Neuron, Central and Peripheral Nervous Systems.
What topics are related to Synapse?
The closest topics to Synapse are Synaptic Transmission, Neurotransmitters, Neuropharmacology, Neuron. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Synapse?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Synapse. To practise the whole of Neuroscience, use the Neuroscience quiz.
How is Synapse different from Synaptic Transmission?
Synapse: The junction where one neuron communicates with another or with a muscle cell. Synaptic Transmission: An action potential triggers calcium entry, vesicle release of transmitter and receptor binding on the postsynaptic cell. Read both side by side and note what each one explains.
How should I study Synapse step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Synaptic Transmission and explain the difference aloud. Finally, take the Neuroscience quiz and come back to this page for any question you miss.