What Are the Key & Lock When Talking About Neural Impulses?

In order to understand the idea of a key and lock when discussing neural impulses, it's necessary to understand a little basic neuron biology. A neuron is a specialized cell in the nervous system that receives, integrates and carries information throughout the body. A neural impulse is an electrical impulse sent between neurons that result an action. The actions can be autonomic, or uncontrolled by thought, such as breathing, or controlled actions, such as picking up a pencil.

Types of Neurons

• There are three types of neurons whose functions are slightly different. Sensory neurons bring information from sensory receptors such as eyes, ears and skin to the central nervous system. Interneurons in the brain and spinal cord translate the information between the sensory and motor neurons. Motor neurons carry the information back from the central nervous system to the appropriate muscles. Neural impulses are carried along all three types of neurons.

Parts of a Neuron

• The neuron is comprised of a number of parts that help conduct the neural impulses from one neuron to another. The soma is the cell body itself. Dendrites are branch-like structures that receive information from other neurons. The axon is a thin, tail-like fiber that extends from the soma to the axon's terminal. It is at this point that a synapse occurs. Axons can be extremely small or as long as three feet and are covered by a myelin sheath that both protects the fiber from damage and helps speed the information along.

Synapses

• Individual neurons don't touch each other directly. Instead there are minute gaps between them called synapses. When a neural impulse reaches the axon's terminal, or the end of the axon, it has to be able to jump that gap to continue to transmit the message. The electrical impulse triggers a release of a chemical messenger called a neurotransmitter. Neurotransmitter molecules bridge the synapse, or gap, between neurons and the message continues onward.

The Key and the Lock

• In order for the message to continue to be conveyed, the neurotransmitter molecules must be compatible with the neuron that is to receive the message. Just like a specific key can only open a specific lock, a specific neurotransmitter can only bind to receptor sites that fit its specific molecular structure. The molecules that are not compatible are either reabsorbed by the neuron transmitting the message, inactivated by enzymes or simply drift away.