The human nervous system is divided into the central nervous system, which consists of the brain and spinal cord, and the peripheral nervous system, which is made up of 31 pairs of spinal nerves and 12 pairs of cranial nerves. It affects body functions such as movement, breathing, and blood circulation.
Structure of the central nervous system
The central nervous system (CNS or CNS) is made up of the so-called gray matter (external) and white matter (internal). The gray matter consists of nerve cells, while the white matter – axons (nerve fibers).
The structures of the CNS include:
- the brain (the brain proper, dumbrain and the brainstem, which consists of the midbrain, the bridge and the medulla),
- spinal cord.
The brain is the main site for receiving and processing information both outside and inside the body. The bones of the skull constitute the protection of the organ. In addition to them, it is also surrounded by three meninges: the dura mater, arachnoid, and the dura mater, filled with cerebrospinal fluid. The blood-brain barrier (the characteristic structure and function of the blood vessels surrounding the brain) is another element of protection, thanks to which only certain substances are permeable.
The brain consists of two hemispheres separated by a longitudinal fissure. The connection between them is provided by nerve fibers located in the great commissural. The surface of the brain is strongly folded, which significantly increases its surface area and the number of nerve cells. The outer part is made of gray matter, while the inner part is made of white matter.
The second major structure of the central nervous system is the spinal cord, which is primarily responsible for transmitting information from the brain to the peripheral system and vice versa. The core, like the brain, protects the bones (the so-called spinal canal), as well as the meninges and the cerebrospinal fluid. In the center of the spinal cord is the middle canal, filled with cerebrospinal fluid, which acts as an extension of the ventricles of the brain. Contrary to the brain, in the spinal cord it is the white matter that surrounds the gray matter. The white matter of the spinal cord consists of axons that send signals from the brain and vice versa, otherwise known as cords.
Structure of the peripheral nervous system
All the nerves that depart from the central nervous system together form the peripheral nervous system (abbreviation: PNS). Peripheral nerves make up the nerve fibers (axons) that form bundles. Due to their functions, we can distinguish sensory nerves (conduct stimuli from receptors to the central nervous system), motor nerves (conduct impulses from the central nervous system to the appropriate organs of the body – e.g. muscles) and mixed nerves (contain sensory fibers and movement).
The human nervous system – ailments
Stroke,Alzheimer’s disease,Parkinson’s disease, meningitis, and concussion are the most common diseases of the nervous system. The list of diseases related to the nervous system is long, and given the fact, their symptoms can be very diverse. Therefore, you should carefully watch your body.
The most common symptoms include:
- headaches anddizziness,
- loss of consciousness orfainting
- muscle cramps
- delirium anddullness
- tremors and convulsions,
- paresisand paralysis (paralysis),
- motor coordination disorders,
- speech disorders or impaired motor coordination,
- memory impairment.
Naturally, not all of them have to be associated with diseases of the nervous system. Sometimes they are caused by diseases of other organs or deficiencies of certain nutrients, so it is worth consulting a doctor in the case of recurring ailments.