workshop week 9 Flashcards
what is the equilibrium potential?
when the electrical potential precisely offsets the tendency for K+ to diffuse down its concentration gradient. This electrical potential is called the equilibrium potential. (the electrical potential at which the magnitude equals and opposes the chemical potential gradient)
what is the simplified version of the nernst equation?
equilibrium potential (Ex) = 61 log10 [X1]/[X2]
how does the nernst equation change with a divalent ion?
the 61 becomes 30.5
how does the nernst equation change with a negative ion? (e.g. Cl-)
the 61 becomes -61
would it be easier or harder to reach threshold potential in a cell with an increase in the extracellular potassium concentration to 10mM?
easier (increasing the extracellular potassium will cause depolarisation and move the resting membrane potential higher and nearer to the threshold potential.
would it be easier or harder to reach threshold potential in a cell with a decrease in the potassium concentration of the extracellular fluid to 2mM?
harder (decreasing the extracellular potassium will cause hyper polarisation and move the resting membrane potential away from the threshold.
would it be easier or harder to reach threshold potential in a cell with an increase in the sodium concentration of extracellular fluid to 180mM?
Easier: increasing the extracellular [Na+] will cause depolarisation and move the resting membrane potential nearer to the threshold (more + ions entering the cell down the concentration gradient)
would it be easier or harder to reach threshold potential in a cell with a decrease in the sodium concentration of extracellular fluid to 110mM?
Harder: decreasing the extracellular [Na+] will cause hyperpolarisation and move the resting membrane potential away from the threshold (fewer + ions entering the cell down the concentration gradient)
