Final answer:
Conductance is the ease with which ions move across a cell's membrane, and increased conductance typically affects the membrane potential by causing depolarization if positive ions enter the cell, or hyperpolarization if the cell loses positive ions or gains negative ions.
Step-by-step explanation:
Understanding Conductance and Membrane Potential
Conductance, in the context of cell biology, refers to the ease with which ions can move across a cell's plasma membrane. This movement is facilitated by ion channels and depends on the electrochemical gradient. The membrane potential is the voltage across the plasma membrane, which arises due to the separation of positive and negative charges on either side of the membrane. An increased conductance means that more ions can cross the membrane.
When there is an increase in conductance, typically due to the opening of more ion channels, the membrane potential is affected. If positively charged ions (like Na+ or Ca2+) flow into the cell, the membrane potential will become less negative (depolarize). Conversely, if positively charged ions leave (like K+), or negatively charged ions enter, the cell will become more negative (hyperpolarize).
In cardiac conductive cells, the increase in conductance, particularly of Na+ and Ca2+, leads to depolarization which, upon reaching a threshold, triggers an action potential. This is critical for the initiation of a guided sequence of events leading to the contraction of the heart muscle. In the case of action potentials within neurons, increased conductance to Na+ initiates depolarization, propelling the action potential down the axon and enabling neural transmission.