The NeuronThe Neuron

The wild wonderful neuron and The wild wonderful neuron and the nervous systemthe nervous system

The NeuronThe Neuron Any of the bundles of fibers Any of the bundles of fibers

interconnecting the central interconnecting the central nervous system and all parts nervous system and all parts of the body, capable of of the body, capable of transmitting sensory stimuli transmitting sensory stimuli and motor impulses from and motor impulses from one part of body to anotherone part of body to another

Nerves can be viewed as Nerves can be viewed as telephone lines connecting telephone lines connecting the body telling it what to dothe body telling it what to do

10 trillion in body! 100 10 trillion in body! 100 billion in brainbillion in brain

in Fetus, develop at in Fetus, develop at 250k /min.250k /min.

an individual nerve cellan individual nerve cell each connect to 10k otherseach connect to 10k others messages to and from brain messages to and from brain

travel along heretravel along here these are chemical-electrical these are chemical-electrical

signals “fired”signals “fired” can use thousand times a can use thousand times a

minute and never stop in minute and never stop in motionmotion

could circle the world 22k could circle the world 22k timestimes

Parts of the neuronParts of the neuron Synapse – gap Synapse – gap

between neuronsbetween neurons Receptors- cells that Receptors- cells that

gather information gather information from the sensesfrom the senses

Effectors- cells that Effectors- cells that work the muscles and work the muscles and internal organsinternal organs

NeurotransmittersNeurotransmitters chemical messages chemical messages

between neurons <think between neurons <think of water valves)of water valves)

messages must travel in messages must travel in one way till done or one way till done or inhibited (stopped)inhibited (stopped)

can be stopped by can be stopped by nerve damage (MS) or nerve damage (MS) or by other neurons acting by other neurons acting on same oneon same one

Types of NeurotransmittersTypes of Neurotransmitters

ACH- controls muscle contractionsACH- controls muscle contractions Serotonin-emotions and happinessSerotonin-emotions and happiness Dopamine-adrenaline, heart rate and Dopamine-adrenaline, heart rate and

blood pressure, balanceblood pressure, balance Histamine-stomach acid productionHistamine-stomach acid production Peptides- sleepiness and arousalPeptides- sleepiness and arousal Endorphins- released to relieve painEndorphins- released to relieve pain

Parts of the NeuronParts of the Neuron axonaxon - the long extension of a - the long extension of a

neuron that carries nerve neuron that carries nerve impulses away from the body impulses away from the body of the cell. of the cell.

cell body (soma)cell body (soma) - the cell - the cell body of the neuron; it contains body of the neuron; it contains the nucleus.the nucleus.

dendritesdendrites - the branching - the branching structure of a neuron that structure of a neuron that receives messages. receives messages.

myelin sheathmyelin sheath - a fatty - a fatty substance that surrounds and substance that surrounds and protects some nerve fibers. protects some nerve fibers.

Types of Nervous SystemsTypes of Nervous Systems