We like to use phrases such as "that annoys me" or "that gets on my nerves" to mean that something is really bothering us. However, nerves and the human nervous system are much more than just indicators of anger or stress.
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Leading Medicine Guide Editors
Article overview
What does the nervous system do?
The basis of the nervous system is the perception of stimuli and the subsequent action or reaction of the body.
Thanks to the nervous system and sensory organs, people are able to perceive their surroundings and react accordingly. For example, if a person perceives via sensory organs such as eyes and ears that a car is about to cross their path, they will quickly avoid it.
An action that seems so clear and simple at first glance is a complex interplay of the nervous system and muscles.
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The subdivision of the nervous system
The human nervous system is divided into two main areas:
- central nervous system (CNS)
- peripheral nervous system (PNS)
The central nervous system includes the spinal cord and the brain. The peripheral nervous system includes all other nerve fibers of the nervous system that run through the body. Their task is to supply the brain and spinal cord with information from the body and the environment. Conversely, the peripheral nervous system receives information on how to react with movements or bodily functions.
The nerve fibers take over the exchange of information . The fibers that lead to the central nervous system are called afferent fibers. The fibers that carry information from the central nervous system to the peripheral nervous system are known as efferent fibers.
A further distinction can be made between the
- somatic nervous system
- autonomic nervous system
The autonomic nervous system controls all important basic functions in the human body and is largely beyond voluntary control. The autonomic nervous system controls, for example, water balance, breathing, digestion and metabolism.
The somatic nervous system, on the other hand, can largely be controlled at will. Movements such as raising the hand are consciously controlled via the somatic nervous system. The somatic nervous system is used to transmit sensory information. Touch and external stimuli such as temperature are thus transmitted to the central nervous system.
This short film gives you a clear illustration of the human nervous system
Anatomical structure of the nervous system
The nervous system is made up of a large number of nerve cells and their projections and glial cells. Billions of nerve cells make up the human brain.
Nerve cells are characterized by the fact that they are excited by changes in the environment and transmit stimuli over very long distances through the body. They can also process the transmitted information and conduct the excitation to other nerve cells or to the muscles or gland cells.
Nerve cells (neurons) are therefore specialized cells for the conduction and transmission of excitation. Together with the glial cells, nerve cells make up the nervous system. In addition to the individual nerve cells, ganglia are also found in the peripheral nervous system. A ganglion is an accumulation of nerve cells. As a ganglion is sometimes even anatomically conspicuous due to a visible thickening, doctors also refer to it as a nerve node.
Structure of a nerve cell
The following structure is typical of mammalian nerve cells: The nerve cell consists of a cell body and a cell process. The cell process can be a dendrite or an axon. The dendrite is a branched projection that is primarily responsible for receiving excitation from other cells. The axon - also known as a neurite - is an extension that serves to transmit excitation.
Axons are surrounded by special glial cells. Axons have the task of transmitting a voltage change by causing a voltage change in the cell membrane through short-lasting ion currents via special channels. This process is also known as an action potential. The action potential causes the transmission of electrical excitation by changing the membrane potential. It is therefore important for every form of stimulus transmission and is considered absolutely necessary to make life possible. The action potential of a nerve cell can even be measured. To this end, researchers have carried out experiments in which they pierced the nerve with a measuring electrode and determined the membrane potential of the cell with another measuring device.
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Typical structure of a neuron
Synapses bridge the gap
The transmission and reception of information in the nervous system does not take place exclusively via electrical excitation. In many cases, synapses are of particular importance for signal transmission in the human body. Synapses are used to exchange information from nerve to nerve.
As a rule, nerve cells are not directly connected to each other. A gap must therefore be bridged in order to exchange information. Doctors also call this gap the synaptic cleft. Synapses are made up of the terminal head of an axon, the dendrite and the gap between them.
Information is rarely transmitted electrically at the synapses, but mostly chemically. The initial electrical signal in the nerve cell therefore becomes a chemical signal at the end of the axon. Electrical excitation of the nerve cell and its axon releases messenger substances known as neurotransmitters . These are now located in the synaptic cleft and are received by the next nerve cell via special docking sites. This chemical information is then converted back into an electrical signal that can continue. This works like a row of dominoes: one cell nudges the next cell to transmit the signal. In this way, a nerve cell can also be directly connected to muscle or gland cells.
Structure of a synapse
Which diseases are related to the nervous system?
There are various diseases that are related to the nervous system. Neurology deals with the nervous system, diseases of the nervous system and possible therapies. Some neurological diseases are very rare, while others are comparatively common. Here too, a rough distinction is made between diseases of the peripheral nervous system and the central nervous system.
Neurological diseases can be caused, for example, by injuries to the brain and spinal cord, infections, genetic predisposition or poisoning. Mental illnesses, on the other hand, are not classified as neurological diseases. The more common diseases of the nervous system include
- Multiple sclerosis
- strokes
- epilepsy
- Alzheimer's disease
- Parkinson's disease
- Craniocerebral trauma
- cerebral hemorrhages
- Meningitis
- Polyneuropathies
Conclusion on the nervous system
Around 86 billion nerve cells must constantly exchange information so that we humans are able to feel, think and act. Highly complex electrical and chemical processes that take place in our body at all times are responsible for this. Nerve cells are therefore masters of communication. In addition, nerve cells have a real team spirit because they always have to work together with other cells in the body.
