Action Potentials definitions Flashcards
Action Potentials definitions
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Action Potential A rapid rise and fall in membrane potential across a neuron's axon, crucial for nerve signal transmission. Resting Potential The stable, negative charge of a neuron at rest, typically around -70 millivolts. Depolarization The process where a neuron's membrane potential becomes more positive, moving towards zero. Threshold The critical level of membrane depolarization, around -55 millivolts, needed to trigger an action potential. Voltage-gated Sodium Channels Protein channels that open in response to membrane depolarization, allowing sodium ions to enter the neuron. Voltage-gated Potassium Channels Protein channels that open during depolarization, allowing potassium ions to exit the neuron, aiding repolarization. Repolarization The process of returning the membrane potential to a negative value after depolarization. Hyperpolarization A state where the membrane potential becomes more negative than the resting potential. Sodium-Potassium Pump A cellular mechanism that restores resting potential by moving sodium out and potassium into the neuron. Electrochemical Gradient The combined effect of an ion's concentration gradient and electrical charge across a membrane. Graded Potentials Small changes in membrane potential that can initiate an action potential if they reach threshold. Excitatory Postsynaptic Potentials (EPSPs) Postsynaptic potentials that make a neuron more likely to fire an action potential. Membrane Potential The voltage difference across a cell's plasma membrane, crucial for action potential generation. Ion Channels Proteins that allow specific ions to pass through the membrane, essential for action potential dynamics. Neurons Nerve cells that transmit information via electrical and chemical signals, fundamental to the nervous system.