Heart pump blood through the heart and into the major arteries. The pacemaker cells make up 1% of cells and form the conduction system of the heart. They are generally much smaller than the contractile cells and have few myofibrils which gives them limited contractibility. Their function is similar in many respects to neurons. Cardiac muscle tissue has autorhythmicity, the unique ability to initiate a cardiac action potential at a fixed rate – spreading the impulse rapidly from cell to cell to trigger the contraction of the entire heart. There are specific proteins expressed in cardiac muscle cells. These are mostly
Cardiac neural crest cells and GATA families of molecules. In addition to these signaling pathways, these processes are also mediated by environmental factors including blood flow, shear stress, and blood pressure. The CNCCs interact with the cardiogenic mesoderm cells of the primary and secondary heart fields, which are derived from the cardiac crescent and will give rise to the endocardium, myocardium, and epicardium. The CNCCs themselves are the precursors to vascular smooth muscle cells and cardiac neurons. For example, CNCCs are required for the formation of the aorticopulmonary septum (APS) that directs cardiac outflow into two tracts: the pulmonary trunk and the aorta of