The Resting Cell Membrane Flashcards
What is the membrane potential?
It is the potential difference across a cell membrane and is always expressed as the potential inside the cell relative to the extracellular solution.
How do we measure the membrane potential in the lab?
Using a micro electrode which is a fine pipettes filled with a potassium chloride (KCl) conducting solution. It can penetrate the cell membrane as it has a very small diameter (1 micrometer)
What is the standard resting potential in nerve cells?
-70mV
What is the range of resting membrane p.ds for animal cells?
-20 to -90mV
Why do cardiac and skeletal cells have such large resting potentials?
Because they are excitable cells it stops them moving from slight changes in action potentials
What is standard resting membrane potential for cardiac myocytes?
-80mV
What is standard resting membrane potential for skeletal muscle myocytes?
-90mV
What is standard resting membrane potential for smooth muscle myocytes?
-50mV
What allows ions to travel across a membrane even though they are impermeable to ions?
Ions channels:
These have a selective permeability to 1 or few ions
Gating- the pore can open or close depending on the conformation change in the transport protein
Rapid ion flow down the electrochemical gradient
In most cells which channel dominates the membrane ionic permeability at rest?
K+ channels
How is an equilibrium potential establish with K+?
Initially potassium ions will flow out of the cell down a concentration gradient, however as they leave the cell they leave a negative charge inside the cell which then draws potassium ions back in, down the electrical gradient
What does the Nernst equation work out?
The Nernst equation allows you to find the resting membrane potential at which that one ion would be at equilibrium.
