Cardiac muscle the walls of a house contain electrical wires and plumbing, cardiac muscle also contains specialised cells for conducting electrical signals rapidly (the cardiac conduction system), and blood vessels to bring nutrients to the muscle cells and take away waste products (the coronary arteries, veins and capillary network). Cardiac muscle cells or cardiomyocytes are the contracting cells which allow the heart to pump. Each cardiomyocyte needs to contract in coordination with its neighbouring cells to efficiently pump blood from the heart, and if this coordination breaks down then – despite individual cells contracting – the heart may not pump at all,
American flamingo volume of lung than a mammal. The American flamingo's four-chambered heart is myogenic, meaning that all the muscle cells and fibers have the ability to contract rhythmically. The rhythm of contraction is controlled by the pace maker cells which have a lower threshold for depolarization. The wave of electrical depolarization initiated here is what physically starts the heart's contractions and begins pumping blood. Pumping blood creates variations in blood pressure and as a result, creates different thicknesses of blood vessels. The Law of LaPlace can be used to explain why arteries are relatively thick and veins are thin. It was