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Nervous tissue, also called neural tissue, is the main tissue component of the nervous system.The nervous system regulates and controls body functions and activity. It consists of two parts: the central nervous system (CNS) comprising the brain and spinal cord, and the peripheral nervous system (PNS) comprising the branching peripheral nerves.
The PNS consists mainly of nerves, which are long fibers that connect the CNS to every other part of the body. The PNS includes motor neurons, mediating voluntary movement; the autonomic nervous system, comprising the sympathetic nervous system and the parasympathetic nervous system and regulating involuntary functions; and the enteric nervous ...
Since there is a broad range of functions performed by different types of neurons in diverse parts of the nervous system, there is a wide variety in the size, shape, and electrochemical properties of neurons. Neurons can be found in different shapes and sizes and can be classified based upon their morphology.
Betz cells are the largest cells (by size of cell body) in the nervous system. [40] The adult human brain is estimated to contain 86±8 billion neurons, with a roughly equal number (85±10 billion) of non-neuronal cells. [41] Out of these neurons, 16 billion (19%) are located in the cerebral cortex, and 69 billion (80%) are in the cerebellum ...
White matter is the tissue through which messages pass between different areas of grey matter within the central nervous system. The white matter is white because of the fatty substance (myelin) that surrounds the nerve fibers (axons). This myelin is found in almost all long nerve fibers, and acts as an electrical insulation.
Glial stem cells are found in all parts of the adult brain. [1] Glial cells greatly outnumber neurons and apart from their supporting role to neurons, glia – astrocytes in particular have been acknowledged as being able to communicate with neurons involving a signalling process similar to neurotransmission called gliotransmission. [4]
Again, adjacent areas on the skin are represented by adjacent neurons in all aforementioned structures. This projection pattern has been termed somatotopy. One common diagram of the somatotopic map is the cortical homunculus. This illustration is a fairly accurate representation of how much cortical area represents each body part or region.
Both neurons and glial cells come in many types (see, for example, the nervous system section of the list of distinct cell types in the adult human body). Neurons are the information-processing cells of the nervous system: they sense our environment, communicate with each other via electrical signals and chemicals called neurotransmitters which ...