Neurons, Impulses and Neurotransmitters
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Neurons, Impulses and Neurotransmitters

Neurons, the functional units of the brain, send impulse to each other. These are transferred from on cell to the next by substances called neurotransmitters. Learn more here...

The neuron is the basic working unit of the brain, a specialized cell designed to transmit information. A human brain contains approximately 50 – 100 billion neurons, which determine the structural and functional properties.

Structure of the Neuron

The cell body of the neuron contains the nucleus, cytoplasm and an electrically excitable output fiber called the axon. Most axons give rise to many smaller branches before ending in axon terminals. The contact points between neurons, used for communicate between cells, are called synapses. Other structures, known as dendrites extend from the cell body and receive messages from other neurons. The dendrites and cell body are covered with synapses formed by the ends of axons of other neurons.

Figure 1: The structure of a typical neuron.

(Source: http://www.web-books.com/eLibrary/Medicine/Physiology/Nervous/Nervous.htm)

Impulses

Nerve impulses involve the opening and closing of ion channels, that allow ions or small molecules to enter or leave the cell. The flow of these ions (which are charged atoms or molecules) creates an electrical current, producing tiny voltages across the cellular membrane. The small difference in electrical charge between the inside and the outside of the cell, determines the ability of the neuron to fire.

When a nerve impulse begins, a dramatic reversal occurs at one point on the membrane. This change, called the action potential, then passes along the membrane at speeds up to several hundred miles per hour. So, many impulses can be sent as one second passes.

Neurotransmitters

When these voltage changes reach the end of the axon, the release of neurotransmitters is triggered. These neurotransmitters, or the brain’s chemical messengers, are released at nerve ending terminals, diffuse through the intrasynaptic space and bind to receptors on the surface of the target neuron. These receptors act as switches for the next cell.

Each of them has a distinctly shaped part that selectively recognizes a specific chemical messenger. A neurotransmitter fit into this receptor like a key in a lock. When the neurotransmitter is in place, the neuron’s outer membrane potential (which means the excitability) is altered and a change is stimulated, such as the contraction of a muscle or the increased activity of an enzyme in a cell.

Knowledge of these neurotransmitters and the action of drugs in these chemical substance is a very important field in neuroscience. With the help of this information, scientists hope to understand the circuits and chemical pathways responsible for disorders such as Alzheimer’s disease and Parkinson’s disease. Understanding the various chemical circuits in the brain is vital to increase knowledge about the storing of memories, the motivations that drive people and the biological basis of mental illnesses.

Source

Brain Facts: A Primer on the Brain and Nervous System. Society for Neuroscience.

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Comments (5)
Sosina Hailu

Thanks.

Nice informative work.

Good info, thanks.

It's amazing just how complex the brain is with all those neurons and electrons firing impulses everywhere...

The brain is a mysterious human organ that puzzles everyone. That's how wonderfully made each one of us is.

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