BIOB34H3 Chapter Notes -Voltage-Gated Potassium Channel, Threshold Voltage, Tandem Pore Domain Potassium Channel
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Graded potentials depolaraizations or hyperpolarizations that occur in the dendrites and cell body (or sometimes in the axon terminals: the changes in membrane potential have an amplitude directly proportional to the strength of the triggering event. What causes graded potential: in the cns and the efferent division, chemical signals from neurons open chemically gated ion channels. Allows ions to enter or leave the neuron: in some sensory neurons, a mechanical stimuli (e. g. stretch) opens or closes ion channels. Closing ion gates can cause depolarization too: e. g. closing the k+ gate and retaining k+ Figure 8. 7 show graded potential where: a stimulus opens a monovalent cation channel allowing sodium influx, positive charge sends a wave of depolarization through the cytoplasm. Local current the wave of depolarization that moves through the cell. Convention: current is the net movement of positive electric charge: initial amplitude (or depolarization strength) in a graded potential is determined by how much charge enters the cell.