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Human Nervous system

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The nervous system is the part of an animal's body that coordinates its voluntary and involuntary actions and transmits signals between different parts of its body. Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago.

In most animal species it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS contains the brain and spinal cord. 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. The PNS includes motor neurons, mediating voluntary movement; the autonomic nervous system, comprising the sympathetic nervous system and the parasympathetic nervous system, which regulate involuntary functions, and the enteric nervous system, which functions to control the gastrointestinal system.

At the cellular level, the nervous system is defined by the presence of a special type of cell, called the neuron, also known as a "nerve cell". Neurons have special structures that allow them to send signals rapidly and precisely to other cells. They send these signals in the form of electrochemical waves traveling along thin fibers called axons, which cause chemicals called neurotransmitters to be released at junctions called synapses. A cell that receives a synaptic signal from a neuron may be excited, inhibited, or otherwise modulated. The connections between neurons can form neural circuits and also neural networks that generate an organism's perception of the world and determine its behavior. Along with neurons, the nervous system contains other specialized cells called glial cells (or simply glia), which provide structural and metabolic support.

Nervous systems are found in most multicellular animals, but vary greatly in complexity.[1] The only multicellular animals that have no nervous system at all are sponges, placozoans and mesozoans, which have very simple body plans. The nervous systems of the radially symmetric organisms the ctenophores (comb jellies) and cnidarians (which include anemones, hydras, corals and jellyfish) consist of a diffuse nerve net. All other animal species, with the exception of a few types of worm, have a nervous system containing a brain, a central cord (or two cords running in parallel), and nerves radiating from the brain and central cord. The size of the nervous system ranges from a few hundred cells in the simplest worms, to around 100 billion cells in humans.

The central nervous system functions to send signals from one cell to others, or from one part of the body to others and to receive feedback.

Label Brain Diagram Printout. Nervous System.

Pineal gland

Nervous system. The nervous system is the part of an animal's body that coordinates its voluntary and involuntary actions and transmits signals between different parts of its body.

Nervous system

Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago. Central nervous system. Anatomy and Physiology. BrainInfo. THE BRAIN FROM TOP TO BOTTOM. Brain Parts Function. 3: Brain regions and their functions. Skip to main content En español Home » Understanding Drug Abuse and Addiction: What Science Says » Section I » 3: Brain regions and their functions Understanding Drug Abuse and Addiction: What Science Says 3: Brain regions and their functions Certain parts of the brain govern specific functions.

3: Brain regions and their functions

Prev Index Next This page was last updated January 2007 Understanding Drug Abuse and Addiction: What Science Says NIDA Publications Teaching Packets. Brain Structures and Their Functions. The Whole Brain Atlas. Neurophysiology. Neurophysiology (from Greek νεῦρον, neuron, "nerve"; φύσις, physis, "nature, origin"; and -λογία, -logia) is a branch of physiology and neuroscience that is concerned with the study of the functioning of the nervous system.

Neurophysiology

The primary tools of basic neurophysiological research include electrophysiological recordings such as patch clamp and calcium imaging, as well as some of the common tools of molecular biology. Neurophysiology is connected with electrophysiology, neurobiology, psychology, neurology, clinical neurophysiology, neuroanatomy, cognitive science, biophysics, mathematical biology, and other brain sciences.[1] History[edit] Neurophysiology has been a subject of study since as early as 4,000 B.C. In the early B.C. years, most studies were of different natural sedatives like alcohol and poppy plants.

In 177 Galen theorized that human thought occurred in the brain, as opposed to the heart as Aristotle had theorized. See also[edit] References[edit] Sources[edit] First map of the human brain reveals a simple, grid-like structure between neurons. In an astonishing new study, scientists at the National Institutes of Health (NIH), have imaged human and monkey brains and found… well, the image above says it all.

First map of the human brain reveals a simple, grid-like structure between neurons

It turns out that the pathways in your brain — the connections between neurons — are almost perfectly grid-like. It’s rather weird: If you’ve ever seen a computer ribbon cable — a flat, 2D ribbon of wires stuck together, such as an IDE hard drive cable — the brain is basically just a huge collection of these ribbons, traveling parallel or perpendicular to each other. There are almost zero diagonals, nor single neurons that stray from the neuronal highways. The human brain is just one big grid of neurons — a lot like the streets of Manhattan, minus Broadway, and then projected into three dimensions. This new imagery comes from a souped-up MRI scanner that uses diffusion spectrum imaging to detect the movement of water molecules within axons (the long connections made by neurons). “Before, we had just driving directions.