The Cardiovascular System is one of the most important systems in your body. It is your body's delivery system for the circulation of blood. It is made up of blood, blood vessels and the heart.

Blood moving away from the heart delivers oxygen and nutrients to every part of your body through arteries. You can remember the function of arteries by recalling that "A" stands for "away from the heart." And your heart has to have enough pressure to get that blood down to your fingertips and to the tip of your toes. On the other hand, 'veins' carry blood back to the heart. So arteries carry blood away from the heart and veins carry blood back to the heart. Interestingly enough, veins have to carry blood back UP to the heart, against gravity, while you are standing up, running or walking up the stairs. That is quite a feat when you think about it. So you can visualize how important proper blood pressure is to get that blood circulating down and back up to the heart. It's one big ol' circle.

The arteries will carry blood away from your heart to smaller and smaller blood vessels called capillaries. So when you go to the doctor and they squeeze your fingertips, they are looking at the rate of your capillary refill. Or when you have surgery, you may be asked to remove your fingernail polish or false fingernails. Before, during or after surgery they may check the rate of your capillary refill. It's a form of checking your blood pressure. Capillaries connect the ends of the smallest arteries (arterioles) with the beginnings of the smallest veins (venules) to send the blood back to your heart through the veins.

Blood moving back to the heart picks up waste products like a trash truck so that your body can get rid of them. Veins carry the blood back to the heart and it does this against gravity. That's quite a feat when you think about it. So again, there has to be enough pressure generated from the heart in order to get the blood to your fingers and toes, and then back up to the heart again. That's a lot of pressure. Too much or too little pressure can be detrimental to your health.

Your Heart is about the size of your clenched fist. And your heart is indeed a muscle. The muscle fibers in the heart are different than the muscle fibers on your legs or that line your organs and blood vessels. This type of muscle fiber is called "cardiac muscle." These muscle fibers branch out and (anastomose) form a continuous network. At intervals, there are prominent bands or intercalated disks that cross the fibers. The special fibers in the heart are called Purkinje fibers. The Purkinje Fibers form the impulse-conducting system of the heart.

Your heart contracts and relaxes approximately 70 or so times a minute at rest. And of course it will contract more when you are exercising. Muscles contract and relax, that's what they do. The heart muscle squeezes and pumps blood through its four chambers to all parts of your body. And it pumps blood through an phenomenal collection of blood vessels. Your blood stream will travel through a pipeline that is very rubbery in nature. This pipeline has tons of branches that are both small and large.

When you inhale, you breathe in air and then send it straight down to your lungs. Blood is pumped from the heart to your lungs. This is where oxygen from the air that you've breathed in gets mixed with the blood. The oxygen-rich blood travels back to the heart where it is pumped through your arteries, to the capillaries and to the rest of the whole body. This system delivers oxygen to all the cells in your body. This includes your skin, bones and other organs. Yep! Even your bones need blood. Your veins will then carry the oxygen-depleted blood back to the heart for another ride in this huge circulatory system.

The majority of your blood is a colorless liquid called plasma.

Red blood cells [RBC's] make the blood look red and it's the RBC's that deliver oxygen to the cells in the body and carry back waste gases in exchange. The RBC's look like tiny little inner tubes or donuts under a microscope. In the middle is where the oxygen sits.

White blood cells [WBC's] are part of your body's defense against disease. Some WBC's will attack and kill germs by devouring them and others will attack and kill by manufacturing and waging chemical warfare agents against disease.

Platelets are other cells that help your body repair itself after injury. Platelets play an important role in blood coagulation, hemostasis and blood thrombus formation. When a small vessel is injured, platelets adhere to each other and the edges of the injury and form a plug that covers the area. The plug or blood clot formed soon retracts and stops the loss of blood.

JUST THE FACTS:

• If you strung together your blood vessels, they could circle the globe 2 1/2 times!
• The average 3-year-old has two pints of blood in their body!
• The average adult at least five times more blood in their body than a 3-year-old!
• The adult heart pumps nearly 4000 gallons of blood each day!
• Your heart beats approximately 30 million times a year!
• The adult body contains over 60,000 miles of blood vessels!
• A "heartbeat" is the sound of the valves in the heart closing when they push blood through its 4 chambers.

[ back to top ]

DISCLAIMER