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From the simple to the complex

Function by Level of Organization

The “Coming Out” of the Electrical Synapse

The electrical conduction of nerve impulses within neurons must not be confused with electrical synapses, which can send electrical signals directly from one neuron to another.


All of our sensations, movements, thoughts, and emotions are the result of communication between neurons. This communication is carried out by two complementary processes: electrical conduction and chemical transmission.

Electrical conduction lets nerve impulses travel rapidly within a neuron.

It involves a brief electrical fluctuation that propagates down the neuron’s dendrites, then through its cell body and out to the tip of its axon.

Electrical conduction is what gives the nervous system the rapid-response capability that is lacking in the body’s other major means of communication, the hormonal system.

Chemical transmission takes place in the synapses between neurons, enabling nerve impulses to be transmitted from one neuron to the next.

This process is called “chemical transmission” because the diffusion of chemical molecules from one neuron to the next is what enables the electrical impulse to be reconstituted in that second neuron.

Chemical transmission gives the brain the flexibility that is required for learning.

However, not all of the thousands of connections that a neuron receives are designed to facilitate the transmission of nerve impulses. Some may even make this transmission more difficult. The neuron must therefore find a way of integrating these various commands.


Neurons need to send nerve impulses rapidly from one end of the human body to the other. To speed up neural conduction along their axons, neurons often receive help from surrounding glial cells.

These glial cells wrap themselves around the axon, forming an insulating sheath somewhat like the insulation that covers electrical wires. This sheath, made of a fatty substance called myelin, enables nerve impulses to travel along the axon more quickly.

It is something like wrapping tape around a garden hose that is full of holes, in order to increase the water pressure.

Similarly, the myelin sheath wrapped around the axon accelerates neural conduction.

This sheath is wrapped around the axon in segments that make it look like a string of sausages.
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