Cellular Electricity

Question 1

Transmembrane Potential

Answer 1

The difference in charge (positive and negative voltage) between the inside and outside of the membrane.
Imports to muscle fibers and neurons.
Changes with cell membrane permeability.
In response to chemical or physical stimuli.

Question 2

Requirements for transmembrane potential

Answer 2

Concentration gradient of ions on each side of the membrane.
Selectively permeable membrane with selective ion channels.
Maintenance of charge difference across membrane (sodium-potassium pumps).
Inside of cell more negative than outside of cell (resting potential -70mv).
At rest there is more sodium outside cell and more potassium inside cell.

Question 3

Key concept of transmembrane potential

Answer 3

Potential exists across membrane because:
Cytosol and extracellular fluid have different chemical/ionic balance.
The cell membrane is selectively permeable.

Question 4

Resting potential

Answer 4

Intercellular negative charge that exists when neuron is not electrically active.
Must be maintained for homeostasis.
Concentration differences in ions needs to be maintained.