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It was in the decade of 1990 that molecular mechanisms of behavioral phenomena became widely known (Eric Richard Kandel)." A microscopic examination shows that nerves consist primarily of axons, along with different membranes that wrap around them and segregate them into fascicles.
The neurons that give rise to nerves do not lie entirely within the nerves themselves—their cell bodies reside within the brain, spinal cord, or peripheral ganglia Glial cells (named from the Greek for "glue") are non-neuronal cells that provide support and nutrition, maintain homeostasis, form myelin, and participate in signal transmission in the nervous system.
A very important type of glial cell (oligodendrocytes in the central nervous system, and Schwann cells in the peripheral nervous system) generates layers of a fatty substance called myelin that wraps around axons and provides electrical insulation which allows them to transmit action potentials much more rapidly and efficiently.
Recent findings indicate that glial cells, such as microglia and astrocytes, serve as important resident immune cells within the central nervous system.
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The nervous system is the part of an animal's body that coordinates its actions and transmits signals to and from different parts of its body.
Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago.
In vertebrate species it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The PNS consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body.
A protoplasmic fiber runs from the cell body and branches profusely, with some parts transmitting signals and other parts receiving signals.The enteric nervous system functions to control the gastrointestinal system.Both autonomic and enteric nervous systems function involuntarily.The head segment contains the brain, also known as the supraesophageal ganglion.In the insect nervous system, the brain is anatomically divided into the protocerebrum, deutocerebrum, and tritocerebrum.
The vertebrate nervous system can also be divided into areas called grey matter ("gray matter" in American spelling) and white matter.