Final answer:
Impermeable ions contribute to maintaining the cell's membrane potential by creating a charge difference across the cell membrane, which is essential for various cellular functions such as electrical signaling.
Step-by-step explanation:
Effects of Impermeable Ions on Cell Function
The semi-permeable membrane of a cell controls the movement of ions in and out of the cell, maintaining different ion concentrations on each side. Diffusion moves the K+ (potassium) and Cl- (chloride) ions until the Coulomb force prevents further transfer, causing a layer of positive charge on the outside and a layer of negative charge on the inside. This creates a voltage across the cell membrane. Normally, the membrane is impermeable to Na+ (sodium ions), which is crucial for the cell's resting membrane potential.
Ions such as Na+, K+, Ca2+, and Cl- are integral for many cell functions but cannot diffuse freely due to their polarity. They move through specific ion channel proteins that allow the formation of a concentration gradient. Some of these channels are always open while others can be gated, opening or closing in response to electrical or chemical stimuli, contributing to the membrane potential.
Electric currents along the cell membrane can be created when its permeability is altered. A stimulus can make the membrane temporarily permeable to Na+, which then rushes in, altering the membrane potential and resulting in a voltage pulse as part of an electrical signal. This change is a crucial step in processes such as neuron firing and muscle contraction.