Dorothy FarrarNerve tissue
Nerve tissue is made up of nerve cells (neurons) and glial cells and is found primarily in the brain , spinal cord , intestine and peripheral nerves. It is used for excitation and stimulus transmission.
Definition
Nervous tissue is one of the four basic types of tissue in the body , along with muscle tissue, epithelial tissue and connective tissue . While the nerve cells are more responsible for the conduction of excitation, the glial cells take over the tasks of the connective tissue and nourish, support and insulate the neurons. Glial cells and neurons form a tight functional unit.
In the human body, nerve tissue appears in shades of pink to white. However, one speaks of the gray and white matter, since prepared nerve tissue appears gray due to the formalin used. The gray matter mainly contains nerve cells. The white matter, on the other hand, consists of nerve tracts.
Anatomy
Nerve tissue consists of nerve cells, the neurons, on the one hand, and glial cells on the other. Nerve cells are highly specialized cells and consist of a cell body (soma) and the cell processes. The cell processes are also referred to as dendrites or axons.
Dendrites are tree-like branches of the cell body. They act as afferent processes, that is, they absorb the incoming electrical charge and conduct it to the cell body. Axons can be up to a meter long. They conduct the excitation away from the cell body. The axons are extensions of the soma that lead away. At its end, the axon divides into many branches and connects to other cells via synapses .
Synapses are switching points for excitation transmission. They transmit stimuli either from one cell to another or from a nerve cell to the target organ.
A distinction is made between the glial cells of the peripheral nervous system and the glial cells of the central nervous system. In the peripheral nervous system there are, for example, Schwann cells , mantle cells or Müller cells. The glial cells of the central nervous system include astrocytes, oligodendrocytes , ependymal cells, microglia, and radial glia.
Function
Nerve tissue serves to absorb stimuli, generate stimuli, conduct stimuli and process stimuli. Electrical impulses are transmitted via the neurons. This process is also known as excitation conduction. Since the nerve cells are connected in a huge network, the excitation can travel from any part of the body to any other part or organ.
The excitations run at an estimated speed of 350 km/h. The neurons, i.e. the nerve cells, are responsible for this conduction. The glial cells outnumber the nerve cells. The central nervous system is made up of almost 90% glial cells. On the one hand, the glial cells are responsible for supporting the neurons. They give the nerve tissue structure and support. On the other hand, the so-called myelin sheaths are formed from the glial cells.
Myelin sheaths act as a kind of insulation for the nerve cells and thus enable a significantly faster transmission of stimuli. Glial cells not only insulate the nerve cells, they are also responsible for nourishing the cells. They take over metabolic and transport processes and regulate the milieu around the nerve cells.
They are also involved in synapse formation and the blood-brain barrier . Defense processes such as phagocytosis are also among the tasks of the glial cells.
Diseases
- Amyotrophe Lateralsklerose (ALS)
Amyotrophic lateral sclerosis (ALS) is an incurable disease of the nerve tissue. This leads to progressive and irreversible damage to the motor neurons. These degenerative processes lead to muscle weakness , paralysis , muscle wasting and spasticity.
Those affected suffer from speech disorders, swallowing difficulties and gait disorders. After diagnosis, the survival time is about three to five years. In most cases, the patients die of pneumonia , which is aggravated by paralysis of the respiratory muscles and difficulty swallowing .
Parkinson’s disease also originates in nerve tissue. The disease is characterized by the death of dopamine-producing neurons in the midbrain . Without the neurotransmitter dopamine, numerous physical and psychological functions can no longer be maintained.
The main symptoms of Parkinson’s disease are muscle rigidity, slow movements up to immobility, muscle tremors and an unstable posture. Increased sebum production makes the face of Parkinson’s patients appear creamed. One speaks here of the ointment face. Bladder dysfunction and depression can also result from Parkinson’s disease.
Multiple sclerosis is a chronic inflammatory disease of the myelin sheaths in the central nervous system. For unknown reasons, the body’s own defense cells attack the glial cells of the myelin sheaths, causing inflammation. The sites of inflammation are scattered throughout the white matter of the spinal cord and brain.
Multiple sclerosis is the chameleon of nervous tissue disorders, as it can cause almost any neurological symptom. Typical are visual disturbances , disturbances in eye movements, abnormal sensations in the extremities, numbness or pain. Multiple sclerosis cannot be cured.
Hello and welcome to my Health Guide & Encyclopedia! My name is Dorothy Farrar, and I'm the founder and main author of this platform.
My passion for health and wellness started at a young age when I became interested in the connection between the food we eat and the way we feel. This fascination led me to study nutrition and dietetics in college, where I learned about the importance of a balanced diet and the impact of various nutrients on the body.