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sodium were decre Questions 10-12: The graph below represents varying ECF concen

ID: 3474918 • Letter: S

Question

sodium were decre Questions 10-12: The graph below represents varying ECF concentrations and the corresponding calculated voltages for both potassium and sodium (your values in question 8 and 9 should fall into this graph accordingly!) 60 50 20 Potassium 50 60 -70 100 300 10 50 100 150 ECF lon Concentration (mM) 10. Looking at the data from the graph above, which ion (sodium or potassium) shows a greater degree of change in voltage when ECF concentration is increased from 0 mM to 300 mM. Briefly explain you answer 11. If membrane voltage using normal concentrations (calculated in question 7) is-70 mV, how would you expect membrane voltage to change when a cell is placed into to a diluted solution? 12. How would the scenario in question #11 affect an excitable cells ability to generate an action potential?

Explanation / Answer

10) From the graph given in the question, it is clearly seen that potassium ions show a greater degree of change in voltage when ECF concentration is increased from 0 mM to 300 mM. This is because the cell membrane is more permeable to potassium ions than sodium ions. Further, potassium is mainly intracellular and sodium is mainly extracellular.