00:00The heart pumps blood throughout the body, carrying oxygen and nutrients to every cell.
00:08It's this circulation of blood that is vital to sustaining life.
00:14The heart is an organ made up of several tough layers of muscle.
00:20The pericardium is the thin layer that covers the exterior, while the endocardium lines the inside walls.
00:27The heart is divided into four chambers, two upper and two lower.
00:33The upper chambers, known as the atrium, receive blood coming into the heart.
00:38The lower chambers are the ventricles that pump blood out.
00:43Between each chamber are valves that open and close and help keep the blood moving.
00:49They are the tricuspid, mitral, pulmonary, and aortic valves.
00:53A pumping cycle starts when oxygen-depleted blood returns to the heart after circulating throughout the body.
01:02The blood enters through the right atrium before flowing to the right ventricle.
01:06It's then pumped to the lungs via the pulmonary arteries.
01:10There, blood is rejuvenated by air that's breathed in.
01:15The oxygen-rich blood returns to the heart through the left atrium, where it goes to the left ventricle.
01:20Then, by way of the aorta artery, the fresh blood is pumped throughout the body before the process repeats itself.
01:29That process happens with every heartbeat.
01:33And it's relentless.
01:35The heart beats 100,000 times a day, 40 million times a year, and up to 3 billion times over an average lifespan.
01:46But there are conditions that can disrupt a heartbeat and that normality.
01:51They can range from myocardial infarction or a heart attack to heart disease and hypertension.
01:56In contrast, exercise and emotional excitement can also have an impact on a person's heartbeat.
02:04The various blood vessels that comprise the circulatory system are a network of veins, arteries, and capillaries
02:11that span over 60,000 miles throughout the body.
02:15And the heart is the pump at the center of it.
02:18The heart is the pump at the center of it.
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