The cardiovascular system (both the heart and the circulatory system) is defined as “the network that delivers blood, oxygen, and nutrients to the body's tissues in conjunction with the respiratory system” (Anonymous, 2012). The circulatory system consists of a vast network of tubes that carries the blood to and from all parts of the body. The heart, lungs, arteries, arterioles (small arteries), and capillaries (very tiny blood arteries, also called vessels) carry oxygen- and nutrient-rich blood away from the heart to the rest of the body. The veins and venules (small veins) carry oxygen- and nutrient-depleted blood back to the heart and lungs. The system is enormous – if all these vessels were laid end-to-end, they would extend about 60,000 miles (Boston Scientific Corporation, 2012).
The normal heart is a muscular “pump” just slightly larger than a fist. It contains four chambers that force blood into the rest of the circulatory system. The upper two chambers are called the right and the left atria; the lower two are called the right and left ventricles. The right side of the heart, which is made up of the right atrium and ventricle, collects and pumps blood to the lungs through the pulmonary arteries. The lungs deliver a new supply of oxygen to the blood, making it turn red. Oxygen-rich blood then enters the left side of the heart, which pumps it through the aorta to supply tissues throughout the body with both oxygen and nutrients. Four valves open to let blood flow through and then close to prevent a backflow, in a highly coordinated sequence. These valves are:
1. The tricuspid valve, located between the right atrium and the right ventricle
2. The pulmonary valve, located between the right ventricle and the pulmonary artery
3. The mitral valve, located between the left atrium and the left ventricle
4. The aortic valve, located between the left ventricle and the aorta
Each valve contains a set of flaps, also known as “leaflets” or “cusps.” When a difference in pressure occurs across the valves, it causes these flaps to open, forcing blood in one direction only – into the body. The heart beats continuously, about 70 to 90 times per minute in the average person. That translates into about 100,000 times per day, pumping the equivalent of 1,900 gallons of blood through the body (Boston Scientific Corporation, 2012).
Like any other biological system, the cardiovascular system can develop problems that make it less efficient or even cause it to fail. According to the Mayo Clinic (2012), the term “heart disease” is a broad category, and it describes a range of diseases that affect your heart. “The various diseases that fall under the umbrella of heart disease,” it states, “include diseases of your blood vessels, such as coronary artery disease; heart rhythm problems (arrhythmias); heart infections; and heart defects you're born with (congenital heart defects).”
In addition, “the term "heart disease" is often used interchangeably with "cardiovascular disease." Cardiovascular disease generally refers to conditions that involve narrowed or blocked blood vessels that can lead to a heart attack, chest pain (angina) or stroke. Other heart conditions, such as infections and conditions that affect your heart's muscle, valves or beating rhythm, also are considered forms of heart disease.”
Poor lifestyle choices, such as eating high-fat foods, smoking, and not getting enough exercise can lead to clogged arteries, high blood pressure, heart attacks, stroke, and a failure of the circulatory system. The Centers for Disease Control and Prevention (CDC) (2012) notes that “Cardiovascular disease is the leading cause of death in the United States; one in every three deaths is from heart disease and stroke, equal to 2,200 deaths per day.” However, these can be controlled with lifestyle changes. The Mayo Clinic (2012) recommends you eat a low-fat and low-sodium diet, get at least 30 minutes of moderate exercise every day, quit smoking, and limit the amount of alcohol you drink. There is some evidence that lifestyle changes, along with increasingly more effective medication and surgical treatments, are having an effect upon the prevalence of coronary artery (or heart) disease – according to Fang, Shaw, and Keenan (2011), “Age-adjusted mortality rates for coronary heart disease (CHD) have declined steadily in the United States since the 1960s. Multiple factors likely have contributed to this decline in CHD deaths, including greater control of risk factors, resulting in declining incidence of CHD, and improved treatment.”
The cardiovascular system is a highly efficient means of keeping the body nourished and healthy, although, like any bodily system, it is vulnerable to failure if not properly maintained. Don’t become a statistic. Talk with your healthcare provider about the risk factors that could lead to cardiovascular disease and the steps you can take to prevent it.
Anonymous, 2012. Heart and Circulatory System. [Online] Available at:
Boston Scientific Corporation, 2012. How Your Heart Works. [Online] Available at: http://www.bostonscientific.com/lifebeat-online/heart-smart/how-your-heart-works.html [Accessed 10 October 2012].
Centers for Disease Control, 2012. CDC Features. [Online] Available at:
Fang, J., Shaw, K., and Keenan, N., 2011. Prevalence of Coronary Heart Disease --- United States, 2006-2010, 60(40). CDC Weekly. [Online] Available at: