The heart is a myogenic muscular organ found in all animals with a circulatory system (including all vertebrates), that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions. The vertebrate heart is composed of cardiac muscle, which is an involuntary striated muscle tissue found only in this organ, and connective tissue. Alternative Names: Normal Human Heart Lysate, Human Heart Tissue Lysate, Heart Lysate, Human Heart Lysate