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Neuron Physiology. How do nerves transmit signals and communicate?. www.liv.ac.uk/. Neurons. Selectively permeable to Na + and K + At rest, membrane is polarized ; K + inside cell, Na + outside cell. Sodium channels open and allow Na + to diffuse into the cell.
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Neuron Physiology How do nerves transmit signals and communicate? www.liv.ac.uk/
Neurons • Selectively permeable to Na+ and K+ • At rest, membrane is polarized; K+ inside cell, Na+ outside cell
Inside of cell temporarily more positive than the outside • Depolarization
Outside of cell • Potassium channels open allowing K+ to flow out of cell Inside of cell
Negative charge is restored on inside of membrane • Repolarization
Video from Kahn Academy • https://www.khanacademy.org/science/biology
Action Potential • Action Potential = an electrical event occurring when a stimulus is applied allowing for Na+ to enter the neuron and reverse the polarity of the cell
Action Potential • Localized event • Self-propagating • Moves in one direction Impulse Animation http://kvhs.nbed.nb.ca/gallant/biology/action_potential_propagation.jpg
Impulse travels down axon • Reaches terminal branches – synaptic knobs
Within synaptic knobs are synaptic vesicles • Contain neurotransmitters (ex: acetylcholine) • Synaptic vesicles fuse with membrane • Release contents into synaptic cleft
Neurotransmitters diffuse across the gap and attach to receptors on receiving neuron. • Permeability of membrane changes • Na+ diffuse into receiving cell • Impulse continues • Neurotransmitter removed or destroyed.Transmission Across a Synapse Animation
Neurotransmitters • Acetylcholine = responsible for control of muscle tissue • Histamine = responsible for symptoms of allergic reactions • Dopamine = helps to provide feelings of enjoyment • Seratonin = helps to regulate mood
You Tube Videos • Saltatory Conduction (role of myelin) • Anatomy of a nerve • Nerve Impulse