Structure of the Heart

Heart: The Engine of Life Educational Resources—The Franklin Institute

Although most people know that the human heart doesn’t bear much resemblance to a heart drawn on a Valentine’s Day card, the image can still be a useful way to learn and remember the parts of the heart.

The heart consists of four chambers: two atria on the top and two ventricles on the bottom. Looking at the Valentine’s Day heart, the two rounded humps at the top are rounded like the top of a lower-case “a.” The bottom is shaped like a “v.”

  • Unlike the Valentine’s Day heart, you may have noticed that the pointed base at the bottom of the heart in the image above doesn’t point straight down, but rather curves to the left.

    If you place your hand on your chest, you might be able to more easily detect your heartbeat on the left side. That’s because the left ventricle contracts most forcefully when your heart beats.

  • Of course, since the heart’s main job is to supply blood to the rest of the body, there needs to be a way for blood to enter and exit the organ. The heart connects to a few large blood vessels that help accomplish this task.

    The largest blood vessel is the aorta, or main artery, which carries nutrient-rich blood away from the heart. The pulmonary artery connects the heart with the lungs as part of the pulmonary circulation system.

    The two largest veins that carry blood into the heart are the superior vena cava and the inferior vena cava. They are called "vena cava" because they are the "heart's veins." The superior is located near the top of the heart. The inferior is located beneath the superior.

    A wall called a septum, separates the right and left sides of the heart.

    Valves connect each atrium to the corresponding ventricle below. The mitral valve connects the left atrium with the left ventricle. The tricuspid valve connects the right atrium with the right ventricle.