Final answer:
Connexins are proteins that form channels known as gap junctions between cells, allowing for the direct diffusion of ions and small molecules, and are critical for synchronized functions such as cardiac muscle contractions.
Step-by-step explanation:
Proteins that form channels between cells, enabling ions and small molecules to diffuse directly from one cell to another are connexins. These channels, known as gap junctions, are created when connexins arrange themselves into a configuration called a connexon, and the pores of these connexons in adjacent animal cells align, forming a continuous channel.
This structure is essential in various physiological processes, notably in cardiac muscle, where it allows electrical signals to pass swiftly between cells, facilitating synchronized contractions.