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Unformatted text preview: 10/10/08- IMPULSE o At any given time the great majority of neurons throughout body are inactive (youre not using them). When a neuron is in its inactive form, it is polarized. There is a high concentration of positive ions (positive charge) on the outside of the neuron membrane (mostly sodium). Theres a net negative charge in the cytoplasm side of the membrane (mostly chlorine ions & negative cytoplasmic proteins). When stimulated: Ex: sensory neuron photoreceptor on inside of eye stimulated by light, in ear stimulated by sound waves Stimulated causes neuron membrane to become permeable to sodium ions. When sodium ions come into to the cell, cell becomes depolarized. Positive and negative charges interact with each other, This creates an electric current (this is the impulse). As charge goes down neuron, depolarization continues. When the impulse reaches far enough down the neuron, the beginning becomes re-polarized because the sodium ions are pushed back out to the outside and locked back out by the membrane- Fig 4.14 TYPES OF SYNAPSES o Chemical synapse Communications between sequential neurons When enough neurontransmitter binds to enough neurotransmitter...
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- Spring '09