The Systems of the Body
The Cardiovascular System
Back to the Basics - Our Body

by J. Richard Daw, MD, FACC
Wake Heart and Vascular Associates
February 2010

Overview
It’s hard to believe, but the average human body contains approximately 60,000 miles of blood vessels. The body’s vast network of these capillaries, veins and arteries and the heart make up the cardiovascular system. Our cardiovascular system delivers life-sustaining oxygen and nutrients to organs, muscles and tissue throughout the body and takes away the extra stuff - the waste - that our body doesn’t need.

How It Works
Think of the heart as your body’s engine. Your heart pumps blood into blood vessels. The blood vessels then deliver blood throughout the body.

Arteries are the blood vessels that carry nutrient-packed blood from the heart to all parts of the body. Made up of fibrous tissue and muscle, arteries are strong so they can absorb the powerful pressure created by a heartbeat and slow down the blood flow.

You can feel that wave of pressure that a heartbeat creates in your wrist and neck. It’s called your pulse.

As your blood’s journey continues, your arteries divide into smaller blood vessels called arterioles. Arterioles then divide into the smallest of all blood vessels - capillaries. The capillaries feed organ tissue with oxygen and nutrients they need and take away the waste products that are not necessary to them.

This waste is deoxygenated blood. It travels from the capillaries into veins. Veins are formed by several capillaries that join together. While arteries are strong and thick to withstand the pressure created by heartbeats, veins have thin, relatively slack walls. Veins are constructed differently than arteries because the dark, deoxygenated blood lacks the pressure created by heartbeats. The blood can then slowly ooze through the veins as it travels back to the lungs to be oxygenated once again.

The blood reaches the lungs via the heart. On the heart’s right side, the deoxygenated blood enters the pulmonary arteries and flows to the lungs to collect oxygen. It then travels back to the left side of the heart to begin its life-sustaining journey throughout the body once again.

Cardiovascular Problems
The American Heart Association Web site offers clear, understandable information about common problems related to the cardiovascular system. Here are the basics on several cardiovascular issues.

HEART ATTACK - A heart attack occurs when there is a "clog" in the heart’s plumbing. Arteries constitute the heart’s plumbing system. A blockage in a coronary artery impedes and can even stop the flow of blood to the heart muscle. This damages the heart muscle, which causes a heart attack.

SUDDEN CARDIAC ARREST - Often confused with heart attack, sudden cardiac arrest is a problem with the conductive tissue - the electrical system - of the heart. The heart’s electrical system regulates the way the heart beats. When the electrical system fails it can cause the heart to suddenly stop working. This is sudden cardiac arrest.

HEART FAILURE - The heart muscle is the heart’s engine, pumping blood throughout the body. Heart failure occurs when the heart muscle weakens and cannot pump enough blood to the body.

VALVE DISEASE - The heart contains four valves that open and close to keep blood moving forward properly. If a valve is diseased and doesn’t close properly, it can cause the blood to leak back into the preceding heart chamber (regurgitation). A valve that doesn’t open properly can cause inefficient blood flow (stenosis).

STROKE - A stroke occurs when the blood supply to the brain is impeded or completely stopped. There are two types of strokes - hemorrhagic and ischemic. Ischemic strokes are the most common. They occur when an artery leading to the brain becomes blocked. A hemmorhagic stroke occurs when an artery leading to the brain bursts.

Heart Disease Risk Factors
There are several factors that contribute to your risk of developing heart disease. Some, such as a family history of heart disease or a birth defect, cannot be modified. Others can. Here are some modifiable heart disease risk factors.

DIABETES - If you have diabetes, it’s important to keep it controlled to reduce your risk of heart disease.

HIGH CHOLESTEROL - If your cholesterol level is 240 or more, you run an increased risk of heart disease. Work with your doctor to control your cholesterol with diet and, if necessary, medications.

HIGH BLOOD PRESSURE - Blood pressure - the force that blood exerts when it hits artery walls - is considered high if it is 140 mm Hg and/or 90 mm Hg or higher. Diet, exercise and, if necessary, medication can help decrease blood pressure.

PHYSICAL INACTIVITY - Exercise at least 30 minutes most days of the week. It’s great for your cardiovascular system and your mind.

OVERWEIGHT & OBESITY - Find your body mass index (BMI) by multiplying your weight by 703, dividing by your height in inches and then dividing that number by your height again. If your BMI is 25-30, you are overweight. If it is greater than 30, you are considered obese. Talk to your doctor about how you can make healthy food choices.

SMOKING & DRINKING - Smoking and drinking alcohol to excess directly contribute to heart disease, but they can be hard habits to break. Again, talk to your doctor about the resources that are available to help you kick these habits. There are quite a few.

STRESS - We could all use less stress in our lives. When you feel stress, recognize it. Stop for a few minutes and do some deep breathing. Take a walk. Ask for help. You don’t have to do everything yourself!

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Certified by the American Board of Internal Medicine with a subspecialty in cardiology, Dr. Daw is a member of the WakeMed Health & Hospitals Medical Staff and has been practicing cardiology for 14 years.

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