1/14/25 Flashcards
Ohm’s Law
A fundamental principle in electrophysiology describing the relationship between voltage (V), current (I), and resistance (R):
V= I × R
Resting Potential
The baseline electrical charge across a neuron’s membrane (~-70 mV), maintained by ion gradients and the sodium-potassium pump
Depolarization
A process where the membrane potential becomes less negative due to the influx of positive ions (e.g., Na+).
Hyperpolarization
When the membrane potential becomes more negative, often due to the efflux of positive ions or influx of negative ions.
Action Potential
A rapid electrical signal involving depolarization (Na+ influx) and repolarization (K+ efflux), used for long-distance neural communication.
Voltage Clamp
A technique that holds membrane potential constant to measure ion currents through specific channels.
Current Clamp
A method allowing the membrane voltage to vary naturally, used to observe how neurons respond to inputs.
Sodium-Potassium Pump
A membrane protein that actively transports 3 Na+ ions out and 2 K+ ions in, maintaining the resting potential.
Membrane Potential
The voltage difference across a neuron’s membrane due to ion distribution and charge separation.
Graded Potentials
Small voltage changes in a neuron caused by synaptic inputs, which can add together to reach the threshold for an action potential.
Extracellular Recording
A technique that measures action potentials outside neurons, often used to study population-level activity.
Patch-Clamp Technique
A high-resolution method used to study ion channel currents in isolated cells.
Conductance (G)
The inverse of resistance
G=1/R), representing how easily current flows through a membrane.
Capacitance
The membrane’s ability to store electrical charge, influenced by its phospholipid bilayer structure.
High Resistance, Low Conductance
A state where the membrane restricts ion flow significantly, reducing current.
Low Resistance, High Conductance
A state where the membrane allows ions to flow easily, increasing current.
Hydraulic Analogy of Circuits
Comparing electrical circuits to water flow: voltage as water pressure, current as water flow, and resistance as the pipe size.
Electrode Reporting Negative Potential
When an electrode is inserted into a neuron, it detects the resting membrane potential, which is typically negative due to more negatively charged ions inside the cell compared to the outside.
