User:ILikeOrangeDucks/sandbox

the human nervous system is divided into three sub systems the central nervous system is made up of the brain and spinal chord the peripheral nervous system Nerves that bring information to and from the central nervous system,picks up feelings form the limbs and so on the autonomic nervous system controls organs and functions independently form the CNS parasympathetic or sympathetic normally you are in the parasympathetic mode,but during fight or flight you are in the sympathetic mode,your pupils dilate,you sweat,your heartbeat accelerates inhibits flow of saliva dilates the bronchi secretion of adrenaline inhibits bladder contraction shuts off digestion fight or fright how do these three subsystems of the nervous system communicate with each other they communicate through neurones all of the organs and nerves of the nervous system are made of neurones (100 billion total) neurones react to stimulus by changing it to an electrical impulse neurones communicate between neurones by sending receiving and transmitting these electrical nerve impulses cell body,nucleus,dendrites,axon hillock,myelin sheath,synapses neurones are connected to each other by small gaps or spaces called synapse nerve impulses are carried across the synapses by chemicals called neurotransmitters neurotransmitters are a chemical substance that is released at the end of a nerve fibre by the arrival of a nerve impulse the diffusion across the synapse or junction causes the transfer of the impulse to another nerve fibre ,a muscle fibre or some other structure

the dendrites of a neurone receive messages or stimuli and transform them into nerve impulses the nerve impulses are then transmitted along axons to the axon terminals nerve impulses travel from one neurone to another via neurotransmitters secreted by axon terminals across the synapse neurotransmitters many different neurotransmitters are produced in the brain some are excitatory (stimulate neural activity) while others are inhibitory (decreases neural activity) major neurotransmitters include dopamine,norepinephrine serotonin acetylcholine and epinephrine an imbalance of neurotransmitters is thought to be the cause of numerous diseases.disorders (parkinsons and dopamine,depression and serotonin,addiction and dopamine) neuroplasticity as we learn develop and grow our neurone develop new connections between them each neurone forms about 2500 synapses at birth,growing to 15000 at 2-3 years old,then it gets trimmed back to normal around adulthood at 6000 neurones can live more then 100 years keep the same neurones all our life neurones cannot reproduce ,if you kill one,its gone peripheral NS connects different parts of the body to the central nervous system PNS is made up of all the nerves that run through the body there are two types of nerves sensory nerves and the motor nerves a sensory receptor picks up the stimuli and transforms the stimuli into nerve impulses sensory nerves transmit information in the form of nerve impulses from sensory receptors to the CNS motor nerves transmit impulses from the CNS to the muscles in order to produce voluntary and involuntary movements The CNS the central nervous system is divided into two parts the brain and the spinal chord the brain is divided into three parts the cerebrum the cerebellum the brain stem meninges the cerebrum the largest part of the brain command center of all voluntary movements interoperation of senses and sound intelligence (reading writing speaking) emotions the cerebrum the cerebrum, has an outer layer of gray matter called the cerebral cortex and white matter (the rest of the cerebrum) cerebral cortex (gray matter) directs higher brain functions such as planning reasoning and logic the cerebrum is divided into two hemispheres the left controls everything that is on the right side of the body while the right side of the cerebrum controls everything on the left side the right hemisphere controls the left side of the body artistic expression creativity and spatial understanding (reading a map) the cerebral cortex or the outer part is divided into 4 lobes frontal parietal occipital and temporal each lobe has its own responsibilities temporal lobe:memory,understanding,language occipital lobe:vision frontal:executive functions,thinking,planning,organizing and solving parietal lobe:perception making sense of the world,arithmetic,spelling the cerebrum the inner part of the brain the limbic system contains structures that control a variety of functions thalamus:receives all sensory information (except smell) before relaying it to the cortex hypothalomus controls hunger thirst emotion and the autonomic nervous system amygdala (located in deep in the medial temporal lobes) involved in fear and emotion and the memory of them.very sensitive to stress (autonomic responses) hippocampus regulates emotions and short term memory storage and conversion to long term memory cerebellum is responsable for posture and coronation of movement and balance volume of pyramids and cones ab.h/3 `brain stem is the control center of internal stimuli and involuntary movement sleep walking a dreaming heart rate respiration and blood coughing and sneezing brain evolution spinal chord is a nervous system organ that carries information (nerve impulses) form various parts of the body to the brain A cord between 40 and 50 cm long found inside the vertebral column made of grey matter )inside) and white matter (outside) reflexes are directly to the spinal chord,not brain the peripheral nervous system made up of nerves 12 pairs of cranial nerves 31 pairs of spinal nerves types of nerves sensory nerves carry info from the sensory organs towards the CNS motor nerves carry info from the CNS to muscles and organs reflexes are automatic rapid involuntary responses to a tumulus they are usually controlled by the spinal cord.Information received by spinal cord is automatically redirected to the muscles you touch a hot stove with your hand the sensory nerve cells detect it an redirect the electrical impulse ti the spinal cord which sends it back to the arm muscles making you move your hand the brain only analyses the event after the reaction has occurred the spinal cord a cord between 40 and 50 cm long found inside the vertebral column made of grey matter (inside) and white matter (outside) responsible for transmitting nerve impulses the sensory organs the nervous system receives information about the outside world from the sensory organs the nose (smell) the tongue (taste) tje ear (hearong,sound waves) the skin (touch pressure temperature pain) eyes (vision,sight) the nose olfactory bulb the nose contains olfactory receptors that detect a variety of odours then send a nerve impulse to the brain along the olfactory nerve the tongue the tongue reacts to five taste (bitter,sour,salty,sweet and umami) the taste buds respond to a taste and then send a nerve impulse to the brain along sensory nerves the ear responds to sound waves from the outside world sound waves are generated by the vibration of objects sound waves have the ability to travel through matter,though some insulating materials will absorb sound waves sound waves a sound wave has certain characteristics frequency (or pitch) the number of circles or waves per scone crossing a given point (the human ear can detect between 16 and 28000 cycles per second) wave length from one crest to another of a wave amplitude the height of the wave (also volume) amplitude anatomy of the ear the ear is divided into three section the outer ear (stuff on side of head,tube into the school) the auricle side of head,visible pat of the ear,receives and filters sound waves and directs them to the auditory ear canal the auditory canal a tube lined with fine hairs and glands that secrete cerumen (ear wax) middle ear the inner ear [2015-05-03, 11:04:56 PM] The Midget: the middle ear the ear drum sound waves hit,it vibrates a thin membrane that vibrates when struck by sound waves the ossicles these small home (the hammer the anvil and the stirrup) that vibrate in response to the vibration of the ear drum when voice goes high and low,its frequency,the waves get closer together,or they go faster as you get higher.the volume changes the height of the wave,as it gets louder