Resting Membrane Potential

Question 1

What is responsible for the unequal distribution of inorganic ions between the intracellular and extra cellular fluid?

Answer 1

Pumps and transporters
Chloride pumps
Sodium-calcium exchange
Sodium-potassium ATPase

Question 2

What is hyperkalaemia?

Answer 2

High potassium levels

Normal values are around 4.5mM

Question 3

During the heartbeat, myocardial calcium channels open and result in a substantial increase in calcium permeability. In which direction does the calcium flow?

Answer 3

Calcium would flow into the cell.

Question 4

What is the resting membrane potential of cardiac and skeletal muscle cells?

Answer 4

-80 to -90mV

Question 5

What is the resting membrane potential of nerve cells?

Answer 5

-50 to -75mV

Question 6

What are ion channels?

Answer 6

Ion channels are proteins that enable ions to cross cell membranes.

Question 7

List 3 properties of ion channels.

Answer 7

1. Selectivity for one (or a few) ions. E.g. Na+, K+, Cl-, cation channels.
2. Gating: the pore can open or close by a conformational change in the protein.
3. Rapid ion flow: always down the electrochemical gradient.

Question 8

Is potassium concentration highest inside or outside the cell?

Answer 8

Inside the cell, roughly 160mM compared with 4.5mM outside the cell.