What is the nervous system made of

Structure and function of the nervous system

Peripheral and central nervous system

The highly complex human Nervous system is divided according to its location into the peripheral and central nervous system.

The peripheral nervous system(PNS) includes all the nerves that run through the body as a three-dimensional network like telephone cables through a city. The nerves transmit information encoded as electrical impulses between the spinal cord or brain and the rest of the body. The nerves belonging to the spinal cord are called spinal or Spinal cord nerves, those belonging to the brain accordingly Cranial nerves.

The central nervous system (CNS) is the vital control center. Together with the hormonal system with which it is closely linked, it controls and regulates all body functions from breathing to movement and reproduction to digestion. The central nervous system enables perceptions via the sensory organs and connects people with the environment. In addition, it is the basis of all "higher" functions such as consciousness, feeling, thinking and learning.

The lowest section of the central nervous system is that Spinal cord(RM), which runs down the vertebral canal of the spine from the transition between head and neck to the lumbar spine. On the one hand it is the central cable harness between the body and the brain, on the other hand it is a control center subordinate to the brain. About unconscious Reflexes allows the spinal cord z. B. rapid escape reactions (pulling the foot away when stepping on a nail), it keeps us upright against gravity by regulating the muscle length and tension and is involved in the emptying of the bladder.

Upwards, the spinal cord goes seamlessly into the extended mark as the lowest part of the brain. Extended mark and the one following upwards bridge and the Midbrain together form the Brain stem. Nerve cell clusters (called nuclei) lie between many conduction pathways. regulate vital body functions such as breathing, supply the sensory organs and are involved in movement control. Connected to the brainstem is that Cerebellum, which serves the coordination of movements and the balance reactions. It provides z. B. for ensuring that movements are “correctly dosed” and not overshoot their goal.

The one above the brain stem and cerebellum Diencephalon is also involved in the control of vital processes, such as the regulation of body temperature. In addition, the diencephalon is the central link between the nervous system and the hormonal system. Last but not least, the diencephalon filters the information from the body and the environment before it forwards part of it to the cerebrum (“gateway to consciousness”).

The Cerebrum after all, it is the largest and most evolutionarily youngest section of the brain. It is divided into two by a large longitudinal furrow Halves divided (hemispheres) and has a huge surface due to unfolding in brain convolutions and furrows. In the cerebrum z. B. the reports of the sensory organs are registered and processed (vision becomes recognition) and movements up to complex chains of action are designed. Our thoughts, feelings and moral values ​​are also services of the cerebrum.

Some cerebral functions can now be localized quite precisely. For example, the control commands for voluntary movements have their origin in a band-shaped area of ​​the cerebral surface, which runs from the center of the head like a strand of hair downwards and slightly forward to around the top of the ear. Sensations of touch of the skin arrive in the brain convolutions in front of it. Damage to these areas or the associated conduction pathways, for example from a stroke or a tumor, thus leads to narrowly defined failures. Since the conduction pathways cross in the brain stem, the left half of the body is affected in the case of right-sided brain damage and vice versa.

Protective devices of the central nervous system

The central nervous system is vital for the organism and at the same time very sensitive. So it is not surprising that effective protective devices have developed over the course of millions of years:

  • The brain is well protected under the skull bones, the spinal cord is surrounded by the spine as a solid "shell".
  • Additional protection is provided by three connective tissue skins: The hard meninges and spinal cords lie beneath the cranial bones and vertebrae, and two soft meninges and spinal cord membranes follow inward.
  • The space in between is not empty, but filled with a watery liquid, the Liquor (Cerebrospinal fluid, nerve fluid). There are also cavities in the brain itself Ventricles, which are filled with liquor. The liquor cushions shocks like a pillow of water.

Arbitrary and autonomic nervous system

The nervous system can also be divided into according to its function arbitrary (somatic) and Autonomic Nervous System (autonomic nervous system, involuntary nervous system). While the voluntary nervous system controls all processes that are subject to consciousness and will (e.g. muscle movements), the autonomic nervous system is largely withdrawn from direct voluntary control. These include, in particular, the internal activities of the body such as heartbeat, breathing and digestion. The vegetative nervous system is classically divided into one sympathetic(Sympathetic) and one parasympathetic part (Parasympathetic nervous system). The sympathetic and parasympathetic nervous systems often have opposing effects and their interaction enables an adaptation to the respective needs of the body.


Dr. med. Nicole Menche, Dr. med. Arne Schäffler in: Gesundheit heute, edited by Dr. med. Arne Schäffler. Trias, Stuttgart, 3rd edition (2014). Revision and update: Dr. med. Sonja Kempinski | last changed on at 15:43