Cardiac muscle

Cardiac muscle is a type of striated muscle found within the heart. Its function is to "pump" blood through the circulatory system by contracting.

Unlike skeletal muscles and smooth muscles, which contract in response to nerve stimulation, cardiac muscle is myogenic, meaning that it stimulates its own contraction. A single cardiac muscle cell, if left without input, will contract rhythmically at a steady rate; if two cardiac muscle cells are in contact, whichever one contracts first will stimulate the other to contract, and so on. This transmission of impulses makes cardiac muscle tissue similar to nerve tissue, although the cells are connected by intercalated discs, which conduct electrical potentials directly, rather than the chemical synapses used by neurons.

Specialized pacemaker cells normally determine the overall rate of contractions. The nervous system does contact the heart, but only sends signals to speed up or slow down the heart rate, rather than controlling each beat.

See also

• Heart
• Circulatory system