How the Healthy Heart Works
Your heart is an amazing organ. It continuously pumps blood rich in oxygen and nutrients throughout your body. This fist-sized powerhouse beats (expands and contracts) 100,000 times per day, pumping five or six quarts of blood each minute, or about 2,000 gallons per day.
How Does Blood Travel Through the Heart?
As the heart beats, it pumps blood through a system of blood vessels, called the circulatory system. The vessels are elastic tubes that carry blood to every part of the body.
Blood is essential. In addition to carrying oxygen and nutrients to your body's tissues, it also takes the body's waste products, including carbon dioxide, away from the tissues. This is necessary to sustain life and promote the health of all the body's tissues.
There are three main types of blood vessels:
Arteries: Arteries begin with the aorta, the large artery leaving the heart. They branch many times, becoming smaller and smaller as they carry blood farther from the heart and into the organs. Arteries carry oxygen-rich blood to all of the body's tissues.
Capillaries: Capillaries are small, thin blood vessels that connect the arteries and the veins. Their thin walls allow oxygen, nutrients, carbon dioxide, and other waste products to pass to and from our organ's cells.
Veins: The veins are blood vessels that take blood back to the heart; this blood lacks oxygen and is rich in waste products that are to be excreted or removed from the body. Veins become larger and larger as they get closer to the heart. The superior vena cava is the large vein that brings blood from the head and arms to the heart, and the inferior vena cava brings blood from the abdomen and legs into the heart.
This vast system of blood vessels -- arteries, veins, and capillaries -- is over 60,000 miles long. That's long enough to go around the world more than twice!
Blood flows continuously through your body's blood vessels. Your heart is the pump that makes it all possible.
Where Is Your Heart and What Does It Look Like?
The heart is located under the rib cage, to the left of your breastbone (sternum) and between your lungs.
The heart is a muscle. The strong muscular walls contract (squeeze), pumping blood through the arteries. The major veins that enter the heart are superior vena cava, the inferior vena cava, and the pulmonary veins (which bring oxygen-rich blood from the lungs to the heart). The major arteries that leave the heart are the aorta, the pulmonary artery (which takes oxygen-poor blood from the heart to the lungs where it is oxygenated), and the coronary arteries (which supply blood to the heart muscle itself).
Looking inside, the heart is a four-chambered, hollow organ. It is divided into the left and right side by a muscular wall called the septum. The right and left sides of the heart are further divided into two top chambers called the atria, which receive blood from the veins, and two bottom chambers called ventricles, which pump blood into the arteries.