How do nerves transmit signals and communicate? 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

Inside of cell temporarily more positive than the outside Depolarization

Potassium channels open allowing K+ to flow out of cell 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

Saltatory Conduction (role of myelin) Anatomy of a nerve Nerve Impulse You Tube Videos Saltatory Conduction (role of myelin) Anatomy of a nerve Nerve Impulse