The Cardiovascular System
The cardiovascular system consists of the heart, blood and blood vessels. Its primary function is
to carry nutrients to the body's cells, and waste products away from the body's cells. The average
adult heart is about the size of a clenched fist and weighs around 300 grams. It beats about 100,000
times in one day and 35 million times in a year. During an average lifetime, the human heart will
beat more than 2.5 billion times. The body contains about 5.5 litres of blood which circulates
through the body three times every minute. The average length of an adult's blood vessels is around
150,000km.
Before 1900, heart disease was rare. Heart disease is now the primary cause of death in the world.
Next - heart structure
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