NERVOUS SYSTEM Yournervous systemis the control and communication system of the body. Its job is to send and receive messages. Your nervous system controls all your thoughts and movements.Parts of the nervous systemNeuronsThe cells that make up the nervous system are called neurons. Long, stringyneuronsare perfect for carrying the electrical messages that arethe "language" of the nervous system.BrainThebrainis the command center of your entire body. Thebrainis the body's main information center. It is made of billions of neurons. The brain helps the body respond to the information it receives from the senses. The brain also processes thoughts. When you think, neurons in your brain are working.The brain has three main parts. The largest is the cerebrum, which controls vision, touch, and other senses. It also handles movements you have control over. Thinking takes place in the cerebrum. The cerebellum is another section of the brain. The cerebellum helps control balance and coordination. Another part of the brain is called the brain stem. The brain stem is the link to the spinal cord and it also controls digestion, breathing, and heartbeat.Spinal CordThespinal cordis a tube of neurons that runs up the spine and attaches to the brain stem. Information from nerves that branch out to the rest of the body goes to the spinal cord. Some messages are processed by the spinal cord but most information is sent on to the brain.

Common Diseases of Nervous System

Alzhiemer's Disease-progressive degenerative disorder of brain that affects ability to carry out daily activities of living

Amyotrophic Lateral Sclerosis-ALS / Lou Gehrig's diseasedegenerative disease of neurons resulting in progressive weakness

Bell's Palsy-Damage to facial nerve resulting in paralysis & drooping on one side of face

Cerebral Palsy-Brain damage before or during birth resulting in poor muscle control & spasticity

Cerbrovascular Accident-CVA / strokedecreased blood supply to brain caused by clot / hemorrahge

Encephalitis-Sever inflammation of the braincommonly caused by virus (complication of flu)

Epilepsy-Abnormal electrical impulses in brain that cause bursts of excitement & can result in siezures

Hydrocephalus-Excessive fluid w/in brain....too much CSF

Meningitis-Inflammation of the covering of the brain and spinal cord...meningies

Multiple Sclerosis-MS...an autoimmune disordercauses destruction of myelin sheath resulting in in episodic tremors, weakness, mood swings& vision changes

Neuralgia-Nerve pain caused by an irritated or damaged nerve

Paraplegia-Paralysis from waist downusually result of damage / trauma to spinal cord

Parkinson's Disease-Degeneration of nerve cells in brain that control movement resulting in tremors

Quadriplegia-Paralysis from shoulders down (respiratory assist.)usually result of damage / trauma to spinal cord

Sciatica-Inflammation of sciatic nerve results in pain in thigh & leg(longest nerve in the body)

Seizure Disorders-Disturbance in brain function causing uncontrollable contractions in muscles

Spina Bifida-Birth defect spinal cord not completely enclosedNERVOUS SYSTEM TRIVIA

When the baby is in utero a mass of cells develops that begin the process of creating the brain and nervous system. After a few weeks these calls divide and one group becomes the brain and the other the GI tract. They come from identical cells.Our 30-foot long gut is embedded with cells of the enteric nervous system, the ENS, a complex system of around 100 million nerves which is often referred to as our "second brain". The ENS supervises the processes of digestion and stays in close contact with, and is heavily influenced by, the central nervous system (the CNS) which comprises the brain and spinal cord.The ENS and CNSuse many of the same chemical messengers or neurotransmitters including acetylcholine and serotonin. In fact the gut has more of these receptors than the brain and can operate independently of the brainWhen you take a drug that alters or boosts neurotransmitters in the brain it is also having an effect on the gut. Did you know....- There are more nerve cells in the human brain than there are stars in the Milky Way.- If we lined up all the neurons in our body it would be around 600 miles long.- There are 100 billion neurons in your brain alone.- A newborn baby's brain grows almost 3 times during the course of its first year.- The left side of human brain controls the right side of the body and the right side of the brain controls the left side of the body.- A New born baby loses about half of their nerve cells before they are born.- As we get older, the brain loses almost one gram per year.- There are about 13, 500,00 neurons in the human spinal cord.- The total surface area of the human brain is about 25, 000 square cm.ABOUT THE NERVOUS SYSTEM Thenervous systemis the part of ananimal's body that coordinates its voluntary and involuntary actions and transmits signals between different parts of its body.Nervous tissuefirst arose inwormlike organismsabout 550 to 600 million years ago. In most animal species it consists of two main parts, thecentral nervous system(CNS) and theperipheral nervous system(PNS). The CNS contains thebrainandspinal cord. The PNS consists mainly ofnerves, which are enclosed bundles of the long fibers oraxons, that connect the CNS to every other part of the body. The PNS includesmotor neurons, mediating voluntary movement; theautonomic nervous system, comprising thesympathetic nervous systemand theparasympathetic nervous system, which regulate involuntary functions, and theenteric nervous system, which functions to control thegastrointestinalsystem. At the cellular level, the nervous system is defined by the presence of a special type of cell, called theneuron, 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 calledaxons, which cause chemicals calledneurotransmittersto be released at junctions calledsynapses. 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 alsoneural networksthat generate an organism's perception of the world and determine its behavior. Along with neurons, the nervous system contains other specialized cells calledglial cells(or simply glia), which provide structural and metabolic support. Nervous systems are found in most multicellular animals, but vary greatly in complexity.The only multicellular animals that have no nervous system at all aresponges,placozoansandmesozoans, which have very simple body plans. The nervous systems of theradially symmetricorganisms thectenophores(comb jellies) andcnidarians(which includeanemones,hydras,coralsandjellyfish) consist of a diffusenerve 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 inparallel), 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. Malfunction of the nervous system can occur as a result of genetic defects, physical damage due to trauma or toxicity, infection or simply of ageing. The medical specialty ofneurologystudies disorders of the nervous system and looks for interventions that can prevent or treat them. In the peripheral nervous system, the most common problem is the failure of nerve conduction, which can be due to different causes includingdiabetic neuropathyand demyelinating disorders such asmultiple sclerosisand amyotrophic lateral sclerosis. Neuroscienceis the field of science that focuses on the study of the nervous system. The Nervous SystemCentral Nervous System- the portion of the nervous system consisting of the brain and spinal chord.Spinal Chord- A collection of neurons and supportive tissue running from the base of the brain down to the centre of the backReflex:An automatic response to a stimulus, requiring no conscious efforts (that often only requires the spinal chord)Two Systems.Peripheral Nervous System- All nerves outside the CNS, includes sensory & motor nerves.Somatic Nervous System- The subdivision of the peripheral NS that connects to sensory receptors and to skeletal musclesAutonomic Nervous System- The subdivision of the PNS that regulates the internal organs and glands (bladder, stomach, heart, blood vessels)Sympathetic N S- that mobilizes bodily resources and increases the output of energy during emotion & stress (fight or flight - accelerator)Parasympathetic N S -operates during relaxed states and conserves energy (digest food - brake)Biofeedback(Miller, 1969, 1978) - monitoring devices track the bodily processes in question and deliver a signal (light or tone) whenever a person makes the desired response - e.g., blood pressure, heart rate, brain waves,Basic Units of the Nervous SystemNeurons:Cells that conduct electrochemical signals, the basic unit of the nervous system. Also called a nerve cell.Arborization.Cell Assemblies are collections of cells that work together in neural pathways orcircuits.Glial Cells:cells that hold neurons in place, insulate neurons, and provide neurons with nutrients.The Structure of theNeuronDendrites-a neuron's branches that receive information from other neurones and transmit it toward the cell body.Cell Body -The part of the neuron that keeps it alive and determines whether or not it will fire.Axon-a neuron's extending fibre that conducts impulses away from the cell body and transmits them to other neurones.Myelin sheath -A fatty insulation that may surround the axon of the neuroneNerve -a bundle of nerve fibres (axons and dendrites) in the peripheral nervous system.Synapse-place where transmission of nerve impulses go from one neurone to the next.alt fig- Includes the axon terminal, the synaptic cleft, and receptor sites in membrane of the next cell.Action potential-Electrical impulses or current travelling down nerve cell. Two types of action.unmyelinatedsmooth flow of current or potentialmyelinatedjumping skipping flow of potential hopping down nodesSynaptic end bulb-synaptic vesicles - little sacs that release neurotransmittersNeurotransmitter-a chemical substance that is released by a transmitting neuron at the synapses and that alters the activity of a receiving neuron.eg., acetylcholine - transmits between nerves and muscles dopamine - important in "reward" system and also seems to play inhibitory role, important in schizophrenia & Parkinson's syndrome serotonin - involved in sleep, dreaming, arousal & emotions GABA - involved in regulation of anxietyReceptor sites-lock and key only certain ones fit.excitatory -increase potential of receptor firinginhibitory -decrease probability of receptor firingNeuromodulators-chemical messengers in the NS that increase or decrease the action of specific neurotransmitters. Drugs will affect action ofneurotransmitters: release, re-uptake, block, ...E.g.,Cocaineblocks re-uptake of dopamine leading to longer effects then lowered levelsEndorphins -chemical substances in the nervous system that are similar in structure and action to opiates; they are involved in pain reduction, pleasure, and memory and are AKA endogenous opioid peptides.