The heart is a hard worker
By: Les Riess, M.D.
Imagine working – without a break – 24 hours a day, 7 days a week, 52 weeks of the year for 80 years (or more). That would be quite a feat, wouldn’t it? It happens all the time, with an amazing organ known as the human heart.
Consider this: your heart beats about 4,000 times each hour, which equals over 36 millions beats each year and over 2.5 billion beats in the average person’s lifetime. Hardworking doesn’t even begin to describe this fist-sized powerhouse.
The heart is a hollow, muscular organ, about the size of your fist, with a two very important jobs. First, it carries oxygen and nutrients to all the cells in your body. Second, it collects and transports carbon dioxide and other waste products for disposal.
This process is carried out in a loop, which starts at the heart, branches out through the body through a network of blood vessels and then returns back to the heart. The heart, blood and blood vessels are part of what’s known as the body’s circulatory system. This extensive system of blood vessels, made up of arteries, veins and capillaries, is over 60,000 miles long.
Blood flows continuously through the blood vessels – delivering oxygen and nutrients and collecting carbon dioxide and waste. Your heart is the pump that keeps all this blood moving.
The heart is made up of four chambers. The top chambers are known as the left and right atrium. The bottom chambers are the ventricles. Blood moves from one chamber to another through valves that allow the blood to flow in one direction only.
The system starts when blood that has already circulated through the body (and picked up waste and carbon dioxide) enters the right atrium. From there, the blood flows into the right ventricle and on to the lungs. The lungs fill the blood with oxygen and nutrients and it flows back to the left side of the heart, entering the left atrium and moving on to the left ventricle. From the left ventricle, the blood flows out to the rest of the body to deliver oxygen and nutrients. It eventually returns to the right atrium and the sequence is repeated.
The timing of how the four chambers work together is critical and is controlled by a system of electrical impulses. Each chamber must contract, or squeeze, at just the right time. This starts in the right atrium, with a group of cells called the SA sinoatrial node. They are also known as the heart’s natural pacemaker. The SA cells produce an electrical signal that spreads through the right and left atrium, causing the chambers to contract simultaneously and push blood down into the ventricles.
The ventricles don’t contract at the same time as the atria because the electrical signal is slowed by another group of cells in the right atrium. This group of cells is known as the AV atrioventricular node. The slowing of the electrical signal at the AV node allows the atria to fill the ventricles with blood before the ventricles contract to push the blood out of the heart.
There are a number of things you can do to keep your heart healthy and keep the blood flowing. Some include:
Your heart: it’s a simple, yet complex and pretty ingenious system. Because of a hardworking, muscular, fist-shaped organ – and its own built-in electrical system – blood flows from the body into the right atrium, moves to the right ventricle, then on to the lungs for oxygen; next it flows back to the left atrium, left ventricle and through the body. And it’s going on in your body all day, every day for your entire life – thanks to your heart. That’s pretty amazing.
|Dr. Riess is a board certified family practice physician at Raiter Clinic.|