[PDF] Synapses non obligatoires :

What is a synapse in a brain?

A synapse is a small gap at the end of a neuron that allows a signal to pass from one neuron to the next. Neurons are cells that transmit information between your brain and other parts of the central nervous system. Synapses are found where neurons connect with other neurons.

How does a synapse communicate?

At a synapse, one neuron sends a message to a target neuron—another cell. Most synapses are chemical; these synapses communicate using chemical messengers. Other synapses are electrical; in these synapses, ions flow directly between cells. At a chemical synapse, an action potential triggers the presynaptic neuron to release neurotransmitters.

What is a presynaptic synapse?

At a synapse, the plasma membrane of the signal-passing neuron (the presynaptic neuron) comes into close apposition with the membrane of the target ( postsynaptic) cell. Both the presynaptic and postsynaptic sites contain extensive arrays of molecular machinery that link the two membranes together and carry out the signaling process.

What are some properties of Electrical synapses?

Some properties of electrical synapses: The two neurons are connected by gap junctions, the space between them being much smaller (~2 nm) than that at chemical synapses (~20 nm). In many cases, transmission of action potentials can pass in either direction. Transmission between neurons is as much as ten times faster than in chemical synapses.