Summary of Cardiac Muscle Structure and Heart Chambers

Cardiac Muscle Structure

Cardiac muscle consists of interconnected fibers that specialize in pumping blood. The fibers are composed of cardiac muscle cells arranged in networks, characterized by thickenings known as intercalated discs, which facilitate the conduction of action potentials between cells. This allows for coordinated contractions among muscle fiber groups, leading to a heart rate significantly different from skeletal muscle.

Chambers of the Heart

The heart features four chambers: two upper atria and two lower ventricles. The interatrial septum separates the right and left atrium, containing the fossa ovalis, a remnant of a fetal opening for blood flow. The interventricular septum separates the right ventricle from the left ventricle. Each atrium has a pouch-like auricle that increases its volume capacity. The thickness of the myocardium varies; atrial walls are thinner as they only need sufficient muscle to push blood into the ventricles.