Answer:
c. contraction and relaxation of the heart
Explanation:
The image shows Cardiac Muscle fibers in a longitudinal section, cardiac muscle, called myocardium, have cross-striated muscle cells, it differs from skeletal muscle in, for example, having constant blood flow through blood vessels, usually having 1 central nuclei, being shorter and innervated by the autonomic nervous system, meaning it's involuntary, not having satellite cells, having different release of Calcium during the action potential (cardiac muscle requires extracellular Calcium to contract).
The cell of the myocardium are called myocardiocytes, are joined by intercalated disks to each other and by T-tubules to the cell membrane.
The primary function of cardiac muscle is repeated and constant contraction, coordinated by the electrical conduction system of the hearth. this contraction pumps the blood out of the heart and into the body, supplying oxygen and nutrients and collecting waste products from metabolism.
there are two circuits, PULMONARY and SYSTEMIC,
Pulmonary circulation: includes the right ventricle, which pumps blood to the lungs via the pulmonary artery, and the left atrium, which receives oxygenated blood coming through the pulmonary vein.
Systemic circulation: includes the left ventricle, which pumps oxygenated blood to the body via the Aorta artery, and the right atrium, which receives deoxygenated blood coming through the Cava vein.
