Electrophysiology Flashcards
What is electrophysiology
Measures potential difference (electrical activity) between the inside of the cell and the outside of the cell - which is the membrane potential
What is the membrane potential
Voltage across the neuronal membrane at any moment, represented by the symbol Vm
What is the resting potential of a typical neurone
Between -55 mV and -90mV
Primarily driven by the permeability of potassium ions across the membrane
What is the equilibrium potential
The membrane potential where the chemical and electrical gradients of an ion across a biological membrane are in equilibrium
No net flow of ions across the membrane
Write out the Nernst equation
Determines the equilibrium potential
61.5/valence of the ion. Log10x concentration of ions in/outside the cell
How is the resting membrane potential maintained
The ion pump is a membrane-associated protein that transports ions across the membrane against the concentration gradients at the expense of metabolic energy.
What are most cells resting membrane potential
Negative resting membrane potential
How is each ions different equilibrium potential determined
-intracellular concentration
-extracellular concentration
-valence of the ion
What are the types of electrophysiology
Intracellular (EEG &ECG) and extracellular
Name intracellular recordings of membrane potential
Extracellular electrode
Sharp electrode
Whole-cell patch electrode
EPSP- one cell, based on ion channels activities
What preparations are there for intracellular physiology recordings?
-dissociate neuronal cultures
-acute brain slices
-whole animal
How do we study synapses using electrophysiology
Usually record the intracellular activity in the post-synaptic neurone
-Current clamp
Recording the voltage
How to record extracellularly
As positive ions move into the cell, the extracellular space becomes more negative
- called a field potential or a fEPSP (excitatory postsynaptic potential)
How do we study the properties of ion channels using electrophysiology
Current clamp recordings show the membrane potential is constantly changing, so study the underlying current- ‘voltage clamp’
Outline the current clamp
Measures the membrane potential
-electrophysiological amplifiers are capable of stimulating the cell by injecting current
-intracellular recordings of voltage
Outline the voltage clamp
Records the current required to keep the cell at a fixed membrane potential
Measuring/monitoring what the amplifier is doing to keep the cell at voltage clamp
