Cardiovascular System

Essay by DragonX5Junior High, 9th grade February 2005

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You have about 6 to 9 liters of blood in your body depending on body size. Your resting heart rate and breathing rate... is your resting heart and breathing rate, about 70 beats/min. At rest most of this blood is in the veins throughout your body, not within your arteries or within your lungs. This is because the journey of blood through your body's veins takes longer than that through your arteries or lungs.

During exercise, however, the time needed for the journey of blood through these tiny vein passageways (billions of canals) is lessened. This is because during exercise blood flowing within your venous canal system is pushed along quicker due to the increased action of your muscles and the influence of nerve impulses, which help to squeeze blood out of your veins. This increase in the rate of flow through these canals thus produces a large increase in the amount of blood returning to your right heart from your body.

Here is where the problem of "shortness of breath" may come in, as you get older!

Studies have shown that physical inactivity is a risk factor for heart disease. Overall, the results show heart disease is almost twice as likely to develop in inactive people than in those who are more active. Regular physical activity (even mild to moderate exercise) can help reduce your risk of heart disease. In fact, burning calories through physical activity may help you lose weight or stay at your desirable weight - which also helps lower your risk of heart disease. The best exercises to strengthen your heart and lungs are the aerobic ones like brisk walking, jogging, cycling and swimming.

It is important to remember that the motto no "pain no gain" doesn't apply, simply mild and consistent exercise is needed to...