Tutorial - Week 2 Content Flashcards
If you measured the potential difference between the two ends of a battery and found that it was 0.0047 Voltz, how many milivoltz (mV) would this be?
4.7mV
The equation used to calculate the equilibrium potential is named after which of the following?
Why do we need to know this?
Walther Nernst
Because the historical context of anything done in physiology and knowing when it happened and who made each break through is extremely important! Walther Nernst got a noble prize for his break through
What effect would anions flowing into a cell have on the membrane potential?
They would make it more negative
What does the abbreviation [Cl-] stands for which of the following?
The concentration of chloride
[ ] means the concentration
What effect would cations flowing out of a cell have on the membrane potential?
They would make it more negative
When thinking about the polarity of the membrane potential what do you need to think about?
When thinking about the polarity of the membrane potential you need to think about the direction the ion is moving and the charge on the ion
What does the Nernst equation allow us to calculate and why is it useful?
(Student answer version)
When a cell membrane is permeable to only one ion species the ions will move down their concentration gradient and change the membrane potential. When the membrane potential reaches a particular value the concentration gradient is opposed by an electrical gradient and the system is at equilibrium with no net movement of ions. The Nernst equation is useful as it allows us to calculate what the membrane potential will be when equilibrium, is reached. This is known as the equilibrium potential. The Nernst equation is useful because if we know the intracellular and extracellular ion concentration of the ion that the membrane is permeable to we can work out what the membrane potential will be.
What does the Nernst equation allow us to calculate and why is it useful?
(Marks version)
Marks in dot points
- The Nernst equation allows us to calculate the equilibrium potential OR the potential difference at which the concentration gradient is exactly matched by the electrical gradient.
- The Nernst equation is useful because it allows us the predict the value of the membrane potential.
- In a cell which is selectively permeable to one ion species
- Providing we know the intracellular and extracellular ion concentrations
Answer question ‘a’ from the question sheet
Refer to image and there is a negative infront of the 61
Answer question ‘b’ from the question sheet
Refer to image and there is a negative infront of the 61
Answer question ‘c’ from the question sheet
Write the Nernst equation
