The Appeal to Nature (also, Biologizing; The Green Fallacy): The contemporary romantic fallacy of ethos (that of Mother Nature) that if something is natural it has to be good, healthy and beneficial. E.g., Our premium herb tea is lovingly brewed from the finest freshly-picked natural T. Radicans leaves.
Found only in the heart, cardiac muscle is responsible for pumping blood throughout the body. Cardiac muscle tissue cannot be controlled consciously, so it is an involuntary muscle. While hormones and signals from the brain adjust the rate of contraction, cardiac muscle stimulates itself to contract.
Two pumps (in a single heart) one to pump deoxygenated blood to the lungs; the other to pump oxygenated blood to all the other organs and tissues of the body. Link to discussion of the control of the heartbeat. A system of blood vessels to distribute blood throughout the body.