The NeuronThe building block of

the nervous system.Neuron – A cell

specialized to receive, process, and transmit information to other cells.Bundles of neurons

are called nerves.

Types of NeuronsSensory (afferent) Neurons – Act like one-way

streets that carry traffic from the sense organs toward the brain.Treat the brain to sight, taste, hearing, touch,

smell, pain, and balance.Ex. – When you test the water temperature in

the shower with your hand, afferent neurons carry the message toward the brain.

Types of NeuronsMotor (efferent)Neurons – Form the one-way

routes that transport messages away from the brain to the muscles, organs, and glandsEx – In our shower example, motor neurons

deliver the message from the brain that tells your hand just how much to move the shower control knob.

Types of NeuronsInterneurons –

Relays messages between other neurons, especially in the brain and spinal cord.Brain is basically a

network of billions of intricately connected interneurons.

How Neurons WorkDendrites – A

branched fiber that extends outward from the main cell body and carries information into the neuron.Act like a net that

collects messages.

How Neurons WorkSoma – Part of the

neuron containing the nucleus.Receiving

information from the dendrites and then makes the decision to either pass the information on or stop it.

How Neurons WorkAxon – An extended

fiber that conducts information from the soma to the terminal buttons. Information travels along the axon in the form of an electric charge called the action potential.

The Resting PotentialResting Potential – The electrical

charge of the axon in its inactive state, when the neuron is ready to fire.

http://www.youtube.com/watch?v=YP_P6bYvEjE

The Action PotentialAction Potential – The

nerve impulse caused by a change in the electrical charge across the cell membrane of the axon. When the neuron fires,

this charge travels down the axon and causes neurotransmitters to be released by the terminal buttons.

Sets off a chain reaction like a set of falling dominos.

The Action PotentialAll-or-None Principle – Refers to the fact that

the action potential in the axon occurs either full-blown or not at all.

Synaptic TransmissionSynapse – The

microscopic gap that serves as a communications link between neurons. Synapses also occur

between neurons and the muscles or glands they serve.

Synaptic TransmissionTerminal Buttons –

Tiny bulblike structures at the end of the axonContain

neurotransmitters that carry the neuron’s message into the synapse.

Synaptic TransmissionSynaptic Transmission – Sequence of events

in which the electrical message morphs into a chemical message that easily flows across the synaptic gap or cleft between neurons.

NeurotransmittersNeurotransmitters –

Chemical messengers that relay neural messages across the synapse. Many neurotransmitters are also hormones.

PlasticityPlasticity – The nervous system’s

ability to adapt or change as the result of experience. Plasticity may also help the nervous

system adapt to physical damage.Hugely important in helping us survive.

Glial CellsGlial Cells – Cells

that bind the neurons together. Also provide an

insulating cover (the myelin sheath) of the axon for some neurons, which facilitates the electrical impulse.