And it also contains a second type of intracellular junction known as the desmosome. And the desmosome is basically the intracellular junction that actually glues the two cells together, that holds the two cells together and allows them to stick together when we have that contraction actually taking place. So this is the second important difference between cardiac muscle cells and skeletal muscle cells. So basically, we have our cardiac muscle cells that only contain a single nucleus, they also contain these special connecting regions known as intercalated discs. Now, cardiac muscle cells also contain relatively large mitochondria and that makes sense because the cardiac muscle cells are constantly working, they're constantly pumping that blood throughout the body and so they need to continually make that ATP and that's why they contain large mitochondria. Now, unlike skeletal muscle tissue, which is voluntary because it is controlled by the somatic nervous system, cardiac muscle cell is involuntary because it is controlled by the autonomic nervous system.