ECF potassium level in Look affect the function of nerve s a

ECF potassium level in. Look affect the function of nerve s and muscles. Explain how hyperkalemia will initially affect the resting membranes potential and generates an action potential

Solution

Hyperkalemia

Each cell have the cell membrane that separates intracellular fluid from the extracellular fluid and have the different ionic composition, normally potassium ion is more in ICF and sodium ion is more in ECF. In resting membrane potential, the inside of the cell is negative when compared with outside of cell and the cell membrane is in polarised state.The resting membrane potential in neuron is -70 mV and in skeletal muscle it is -90mV.

Potassium is a positively charged electrolyte. Hyperkalemia is the condition of having high blood serum potassium concentration that is above 5.5 mmol/L. The normal level of potassium is 3.5 - 5.5 mmol/L. Hyperkalemia affects the excitability of nerve cell membrane and muscle cell membrane. An excitable cell depolarises to threshold of -55 mV and generates an action potential. (When the cell membrane is depolarised from its resting to threshold level by the stimulus of 6-7 mV, the action potential starts). The potassium ions shift from intracellular fluid to extracellular fluid. The magnitude of resting potential is proportional to ratio of potassium ion concentration inside the cell to that of outside the cell. In hyperkalemia, the ratio of potassium ion concentration inside the cell to that outside of the cell decreases, in turn the magnitude of resting potential decreases and so the value goes to less negative. Then the depolarisation minimise the difference between the resting potential and threshold potential.

When ECF potassium concentration increase, the cell becomes less negative/partially depolarised, making the cell to reach threshold with ease and generates an action potential.

References:

https://books.google.co.in/books?id=7iMG2zRGu9sC&pg=PA152&dq=hyperkalemia+generates+action+potential&hl=en&sa=X&ved=0ahUKEwiy3dmlvsDRAhWKro8KHVTZD24Q6AEIMzAE#v=onepage&q=hyperkalemia%20generates%20action%20potential&f=false