Nervous tissue is organized into a network of glial cells and neurons. While neurons serve as conduits for excitation, glial cells perform organizational functions. Inflammation, necrosis, and space-occupying lesions in the nervous system can cause permanent damage to nervous tissue.
What is nervous tissue?
In anatomy, nervous tissue refers to interconnected neurons or nerve cells. Glial cells are interposed between individual neurons and connect them to capillaries. This reticulated tissue is present primarily in the brain and spinal cord, but also in the gastrointestinal tract and retina. The color of the tissue is between pink and white. The interconnectedness in the gray matter is higher than that in the white matter. The nerve tissue serves to selectively transmit excitation to the organs. These organs produce certain effects in response to the neuronal impulse. Besides the nervous tissue, the basic tissues include mainly the muscle tissue, the connective tissue and the epithelial tissue. Nervous tissue is the only one of the basic tissue types that consists of cells connected in a network-like manner.
Anatomy and structure
Glial cells and neurons are the components of nervous tissue. The individual composites in nervous tissue are interconnected. Here, excitations are transported along imprinted pathways at speeds of up to 350 kilometers per hour. Glial cells correspond to either astrocytes and oligodendrocytes or Schwann cells, ependymal cells, microglia and satellite cells. Astrocytes sit at the sites of contact of neurons with the bloodstream. Astrocytes run out into many cell processes that feed multiple neurons. They are distributed around the synapse and each neuron is connected to several astrocytes. Schwann cells are found only in the peripheral nervous system. Astrocytes and oligodendrocytes, on the other hand, form the supporting framework of the central nervous system. Microglia such as Hortega cells also connect only neurons in the central nervous system.
Function and tasks
Neurons in nervous tissue are responsible for processing and transporting neuronal excitation. Thus, they perform the function of excitation conduction. Impulses in the neuronal network travel along predefined pathways. They branch out in the nervous tissue to other neurons, coincide with the impulses of certain neurons or inhibit individual neurons. The neuroglia or glial cells of the nervous tissue perform auxiliary tasks in this system. On the one hand, they form the supporting framework of the neurons. On the other hand, they are responsible for their nutrition and for maintaining the biochemical level that the nerve cells need to work. The functions of glial cells have not been fully understood until now. Initially, science assumed a putty substance that merely connects neurons. In the meantime, research has identified a fraction of the diverse tasks. For example, glial cells produce substances that the nervous system needs for nerve function. They also remove metabolic products, dehydrate, and fight invading microorganisms. In addition, glial cells set the pattern for nerve function. Thus, they organize the nervous system as neurons follow the predetermined pattern. For example, neuroglia specify the pathways along which nerve excitations travel through the brain. The cells are also involved in the formation of synapses. The organizational activities of glia culminate in what is called weeding. In this process, the cells remove neurons that do not connect into the frequented pathways. They detach rarely used pathways and consolidate much used ones. Thus, the neurons are the excitation conductors, but the glial cells specify the pathways of this excitation conduction. Thus, the tasks of the cell types in the nervous tissue are closely interconnected. Glial cells and neurons complement each other. The neurons perform the service that is organized by the glial cells. So to speak, the neuroglia act as managers of the neurons.
Diseases
When the drainage function of astrocytes is disturbed, brain edema can form in the central nervous system. Fluid thereby becomes deposited in the brain. This can happen, for example, as part of an inflammation in the central nervous system. Brain edema is a serious condition that can lead to brain death. The blood supply to the brain can be interrupted or at least impeded by the rising intracranial pressure. Treatment of this phenomenon includes draining the cerebrospinal fluid from the external cerebrospinal fluid space.The pressure on the brain is reduced in this way. Draining the brain with medication is also conceivable. An equally threatening disease is the so-called glioma. This collective term covers various tumors of the central nervous system. In addition to astrocytomas, oligodendrogliomas, for example, also belong to the gliomas. These tumors are the most aggressive type of brain tumors and are among the most common. Nerve tissue can also be damaged by primary diseases such as diabetes. Sugar can be stored in the tissue as part of the disease. This substance acts as a neurotoxin in the nerve tissue. Polyneuropathies with sensory disturbances are the result. Necrotizing diseases of the nerve tissue are also not uncommon. Syphilis of the central nervous system, for example, is often associated with necrotizing effects to nervous tissue. Ischemic damage to central nervous tissue, on the other hand, occurs with brain cysts, for example, because these space-occupying lesions can interrupt the blood supply via the cerebral arteries. Inflammatory damage to nerve tissue, on the other hand, occurs in the inflammatory autoimmune disease multiple sclerosis. After their demise, the function of specialized neurons cannot be taken over by neighboring cells. However, because undifferentiated neurons permanently migrate into the brain region, regeneration of nerve tissue is still possible to a certain extent.
