What is the difference between neural transmission and synaptic transmission

If the dendrites receive a strong enough signal from a neighboring nerve cell, or from several neighboring nerve cells, the resting electrical potential of the receptor cell's membrane becomes depolarized. Regenerating itself, this electrical signal travels down the cell's axon, a specialized extension from the cell body which ranges from a few hundred micrometers in some nerve cells, to over a meter in length in others.

This wave of depolarization along the axon is called an action potential. Most axons are covered by myelin, a fatty substance that serves as an insulator and thus greatly enhances the speed of an action potential. In between each sheath of myelin is an exposed portion of the axon called a node of Ranvier. It is in these uninsulated areas that the actual flow of ions along the axon takes place.

The end of the axon branches off into several terminals. Each axon terminal is highly specialized to pass along action potentials to adjacent neurons, or target tissue, in the neural pathway. Some cells communicate this information via electrical synapses. But whereas an electrical signal in an electronic device occurs because electrons move along a wire, an electrical signal in a neuron occurs because ions move across the neuronal membrane.

Ions are electrically charged particles. The protein membrane of a neuron acts as a barrier to ions. Ions move across the membrane through ion channels that open and close due to the presence of neurotransmitter.

When the concentration of ions on the inside of the neuron changes, the electrical property of the membrane itself changes. Normally, the membrane potential of a neuron rests as millivolts and the membrane is said to be polarized. The influx and outflux of ions through ion channels during neurotransmission will make the inside of the target neuron more positive hence, de-polarized.

When this depolarization reaches a point of no return called a threshold, a large electrical signal is generated. This is the action potential. How it is generated is illustrated in the following animation.

This signal is then propagated along the axon and not, say, back to its dendrites until it reaches its axon terminals. An action potential travels along the axon quickly, moving at rates up to meters or roughly feet per second.

Conduction ends at the axon terminals. Axon terminals are where neurotransmission begins. Neurotransmission or synaptic transmission is communication between neurons as accomplished by the movement of chemicals or electrical signals across a synapse. For any interneuron, its function is to receive INPUT "information" from other neurons through synapses , to process that information, then to send "information" as OUTPUT to other neurons through synapses.

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