Facilitated diffusion is usually significant to pass the ions across the hydrophobic layer of the plasma membrane. Transmembrane integral protein and careers proteins provide the channels that allow the ion to pass across the membrane. When an ion bind to their active site on the protein (note that the proteins are very selective), the protein changes conformation. It is this change in conformation opens up the channel that allows the ions to be passed across the membrane. When the ions are released inside of the cell, the protein resumes normal shape (and the channel also closes) and the active site becomes available again or another ion.
Is made using the enzyme DNA polymerase, from the 5' to the 3' end?
Answer:
Gap junctions within the intercalated disks
Explanation: Gap junctions within the intercalated disks allow impulses to be propagated from one cardiac muscle cell to another. It allows sodium, potassium, and calcium ions to flow between adjacent cells, propagating the action potential, and ensuring coordinated contractions.