Transmembrane Resting Potential

Question 1

Briefly list what causes transmembrane resting potential

Answer 1

• K+ leak channels
• Na+K+ATPase
• Presence of negatively charged proteins in cell which are impermeable

Question 2

Describe the process of the Na+K+ATPase pump

Answer 2

Transports 2K+ ions from outside the cell (low conc) into the cell (high conc) and transports 3Na+ ions from inside the cell (low conc) to outside (high conc)

Question 3

How do K+ leak channels contribute to the transmembrane resting potential?

Answer 3

There is a high concentration of K+ ions inside the cell than outside.

K+ leak channels are always open and allow the facilitated diffusion of k+ ions out of the cell.

K+ ions are constantly lost, so the charge inside a cell becomes slightly negative, with the extracellular becoming slightly positive.

K+ moves along gradient until equilibrium is met according to chemical and electrical gradient

Question 4

What do excitable cells utilise the difference in ion imbalance to do?

Answer 4

Generate action potentials

Question 5

What is a K+ leak channel?

Answer 5

A protein in the cell membrane that allows the facilitated diffusion of K+ ions from inside to outside the cell (down its concentration gradient)

Question 6

What is the main way in which the TRP is maintained?

Answer 6

The presence of potassium leak channels

Question 7

What is the purpose of the Na+k+ATPase pump?

Answer 7

Keeps intracellular concentration of K+ an intracellular conc of Na+ high.

This creates a concentration gradient to facilitate leak/diffusion of K+ ions via K+ leak channels

Question 8

What is the transmembrane resting potential in neurones?

Answer 8

~70mV

Question 9

What is transmembrane resting potential?

Answer 9

The electrical gradient between extracellular and intracellular fluid at rest.

Question 10

Why does the Na+K+ATPase pump require energy?

Answer 10

The sodium pump requires energy as it uses active transport to transport both the Na+ and K+ ions against their concentration gradient

Question 11

Why does the presence of Na+ leak channels not offset the change caused by K+ leak channels?

Answer 11

There are very few Na+ leak channels so the offset is negligible

Question 12

Why is the Na+K+ATPase pump known as an electrogenic pump?

Answer 12

3Na+ out of cell and 2K+ in, this means a net loss of 1+ charge from inside the cell

Helps maintain electrical gradient as the inside of the cell becomes negative in regards to the outside

Question 13

Why is Transmembrane Resting Potential important?

Answer 13

It is a store of potential energy and can be used to open voltage-gated membrane channels to send electrical signals

Without a TRP, cells would not be excitable, could not produce action potentials or conduct impulses