Week 3 - The Resting Cell Membrane

Question 1

Briefly describe how membrane potential can be measured experimentally.

Answer 1

1. Using a microelectrode: fine glass pipette. One electrode is inserted into the surrounding solution, whilst one electrode is inserted into a fine glass pipette which penetrates the plasma membrane
2. Tip: less than 1 micrometer
3. Filled with a conducting solution: KCl

Question 2

Which cells have the largest resting potentials? What is the approximate value of their potential?

Answer 2

1. Cardiac and skeletal muscle cells

2. -80- -90 millivolts

Question 3

What is the standard resting membrane potential for a nerve cell?

Answer 3

Approximately -70 millivolts

Question 4

What factors make the whole cell membrane selectively permeable to ions?

Answer 4

1. Ion selectivity of channels

2. Types of channels that are open