Sindjelici 15 epizoda cela online dating

Posted by / 26-Jul-2017 02:53

Sindjelici 15 epizoda cela online dating

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.Both autonomic and enteric nervous systems function involuntarily.Nerves that exit from the cranium are called cranial nerves while those exiting from the spinal cord are called spinal nerves.Recent findings indicate that glial cells, such as microglia and astrocytes, serve as important resident immune cells within the central nervous system.The vertebrate nervous system can also be divided into areas called grey matter ("gray matter" in American spelling) and white matter.Among the most important functions of glial cells are to support neurons and hold them in place; to supply nutrients to neurons; to insulate neurons electrically; to destroy pathogens and remove dead neurons; and to provide guidance cues directing the axons of neurons to their targets.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.

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 sensory information from these organs is processed by the brain.In insects, many neurons have cell bodies that are positioned at the edge of the brain and are electrically passive—the cell bodies serve only to provide metabolic support and do not participate in signalling.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.In the human brain, it is estimated that the total number of glia roughly equals the number of neurons, although the proportions vary in different brain areas.

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