Designer

=//Designer//= == The nervous system is an organ system containing a network of spezialized cells call nerurons that coordinate the actions of an animal and transmit signals between different parts of its body.In most animals the nervous system consists in two parts central and peripheral.The central nervous system of vertebrates (such as humans) contains the brain, spinal cord, and retina. The peripheral nervous system consists of sensory neurons, clusters of neurons called gangila, and nerves connecting them to each other and to the central nervous system. ==

== Everyday in our lives, we perform many different actions and use our five senses, such as lifting an arm to reach for something, opening our mouths to eat, tasting food, reading textbooks and jumping when we touch something hot. Have you ever wondered how we are able to perform such actions and reactions? ==

== Well, all of these have to do with the brain and our nervous systems. To satisfy your hunger for knowledge and for the budding neurologist, let us take an in-depth look at our inner workings. Our inner workings are complex, with many different aspects to it. However, the basic functional unit that allows us to transmit nerve messages is the neuron. Let us now enter the world of the brain and the nerves. Enter the topics here. ==



NEURONS:
 Neurons send signals to other cells as electrochemical waves travelling along thin fibers called axons, which cause chemicals called neurotransmitters to be released at junctions called synapses. A cell that receives a synaptic signal may be excited, inhibited, or otherwise modulated. Sensory neurons are activated by physical stimuli impinging on them, and send signals that inform the central nervous system of the state of the body and the external environment. Motor neurons, situated either in the central nervous system or in peripheral ganglia, connect the nervous system to muscles or other effector organs.

 Central neurons, which in vertebrates greatly outnumber the other types, make all of their input and output connections with other neurons. The interactions of all these types of neurons form neural circuits 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.

The nervous system is defined by the presence of a special type of cell the neuron (sometimes called "neurone" or "nerve cell"). Neurons can be distinguished from other cells in a number of ways, but their most fundamental property is that they communicate with other cells via synapses, which are membrane-to-membrane junctions containing molecular machinery that allows rapid transmission of signals, either electrical or chemical. Many types of neuron possess an axon, a protoplasmic protrusion that can extend to distant parts of the body and make thousands of synaptic contacts.Axons frequently travel through the body in bundles called nerves.

Even in the nervous system of a single species such as humans, hundreds of different types of neurons exist, with a wide variety of morphologies and functions. These include sensory neurons that transmute physical stimuli such as light and sound into neural signals, and motor neurons that transmute neural signals into activation of muscles or glands; however in many species the great majority of neurons receive all of their input from other neurons and send their output to other neurons.   FUNCTION:.  ==At the most basic level, the function of the nervous system is to send signals from one cell to others, or from one part of the body to others. There are multiple ways that a cell can send signals to other cells. One is by releasing chemicals called hormones into the internal circulation, so that they can diffuse to distant sites. In contrast to this "broadcast" mode of signaling, the nervous system provides "point to point" signals neurons project their axons to specific target areas and make synaptic connections with specific target cells.==

=ANATOMY IN VERTEBRATES:=

The nervous system of vertebrate animals (including humans) is divided into the central nervous system (CNS) and peripheral nervous system (PNS).The central nervous system (CNS) is the largest part, and includes the brain and spinal cord. The spinal cavity contains the spinal cord, while the head contains the brain. The CNS is enclosed and protected by meninges, a three-layered system of membranes, including a tough, leathery outer layer called the dura matter. The brain is also protected by the skull, and the spinal cord by the vertebraete.

=NEURONS:=

= **The human Nervous System consists of billions of nerve cells (our neurons) pluss supporting (neuroglial) cells. Neurons are able to respond to stimuli (such as** **touch, sound, light, and so on), conduct impulses, and communicate with each other (and with other types of cells like muscle cells).** = = = = = = **The nucleus of a neuron is located in the cell body. Extending out from the** **cell body are processes called dendrites and axons. These processes vary in** **number & relative length but always serve to conduct impulses (with dendrites** **conducting impulses toward the cell body and axons conducting impulses away** **from the cell body).** = = = = = = **Neurons can respond to stimuli and conduct impulses because a membrane** **potential is established across the cell membrane. In other words, there is** **an unequal distribution of ions (charged atoms) on the two sides of a nerve** **cell membrane. This can be illustrated with a voltmeter.** = = = = =



Interactions:
Respiratory and nervous system:

The brain needs oxygen to work and the respiratory system supplies the whole body with it. The respiratory system takes in oxygen into the bloodstream which nourishes the CNS and allows for optimum operation, the oxygen also helps to renew the nerve fiber "sheaths" that help protect the nerves. They are commonly worn down from over stress and over use of stimulants.

CIRCULATORY AND NERVOUS SYSTEM:

The brain needs oxygen to work and the respiratory system supplies the whole body with it. The respiratory system takes in oxygen into the bloodstream which nourishes the CNS and allows for optimum operation, the oxygen also helps to renew the nerve fiber "sheaths" that help protect the nerves. They are commonly worn down from over stress and over use of stimulants. DIGESTIVE AND NERVOUS SYSTEM

The digestive system actually has its own nervous system called the '//enteric nervous system//' (ENS) that acts almost entirely independently of the brain. The ENS has roughly as many neurons as the spinal cord (~90 million) contained in plexuses that surround the the entire gastrointestinal tract. These include both sensory as well as motor neurons. Together they detect changes in the gut (as a result of ingesting food/drink) and regulate secretion and motility. Although the ENS is under autonomic influence - e.g. increased parasympathetic tone during sleep - the actual influence is limited. In fact the ENS will continue to function normally without any sympathetic/parasympathetic input at all.



MUSCULAR AND NERVOUS SYSTEM:

Parts of the muscular system are involuntary so the nervous system can control it and send signals to move certain muscles. the muscle and skeletal...well muscles and bones usually need to work together to support, protect and contract/relax muscles.



CARDIOVASCULAR AND NERVOUS SYSTEM:

When the heart starts beating fast it gets nervous so the nervous system has to calm it down.



SKELETAL AND NERVOUS SYSTEM:

The skeletal system helps mobilize the body by providing attachment sites for the muscles; producing levers. The nervous system tells the skeletal muscles what do do. So, by controlling the muscles, the nervous system indirectly interacts with the skeletal system.