Neuron Physiology How do nerves transmit signals and

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Neuron Physiology How do nerves transmit signals and communicate? www. liv. ac. uk/

Neuron Physiology How do nerves transmit signals and communicate? www. liv. ac. uk/

Neurons Selectively permeable to Na+ and K+ n At rest, membrane is polarized; K+

Neurons Selectively permeable to Na+ and K+ n At rest, membrane is polarized; K+ inside cell, Na+ outside cell n

n Sodium channels open and allow Na+ to diffuse into the cell

n Sodium channels open and allow Na+ to diffuse into the cell

n Inside of cell temporarily more positive than the outside n Depolarization

n Inside of cell temporarily more positive than the outside n Depolarization

n Potassium Outside of cell channels open allowing K+ to flow out of cell

n Potassium Outside of cell channels open allowing K+ to flow out of cell Inside of cell

n Negative charge is restored on inside of membrane n Repolarization

n Negative charge is restored on inside of membrane n Repolarization

Video from Kahn Academy n https: //www. khanacademy. org/scienc e/biology

Video from Kahn Academy n https: //www. khanacademy. org/scienc e/biology

Action Potential n Action Potential = an electrical event occurring when a stimulus is

Action Potential n 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 n Localized event n Self-propagating n Moves in one direction Impulse Animation

Action Potential n Localized event n Self-propagating n Moves in one direction Impulse Animation http: //kvhs. nbed. nb. ca/gallant/biology/action_potential_propagation. jpg

n Impulse travels down axon n Reaches terminal branches – synaptic knobs

n Impulse travels down axon n Reaches terminal branches – synaptic knobs

n Within synaptic knobs are synaptic vesicles – Contain neurotransmitters (ex: acetylcholine) Synaptic vesicles

n Within synaptic knobs are synaptic vesicles – Contain neurotransmitters (ex: acetylcholine) Synaptic vesicles fuse with membrane n Release contents into synaptic cleft n

n Neurotransmitters diffuse across the gap and attach to receptors on receiving neuron. n

n Neurotransmitters diffuse across the gap and attach to receptors on receiving neuron. n Permeability of membrane changes n Na+ diffuse into receiving cell n Impulse continues n Neurotransmitter removed or destroyed. Transmission Across a Synapse Animation

Neurotransmitters n Acetylcholine = responsible for control of muscle tissue n Histamine = responsible

Neurotransmitters n Acetylcholine = responsible for control of muscle tissue n Histamine = responsible for symptoms of allergic reactions n Dopamine = helps to provide feelings of enjoyment n Seratonin = helps to regulate mood

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

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