Anatomy: Animals Inside

Circulatory System

What is blood pressure, and why is it important?

Blood pressure is the lowest in the veins and the highest in the arteries when the ventricles of the heart contract. Currently, the blood pressure for normal, resting adults is 120/80 (although this is often debated, depending on the doctor). This means that the systolic number (the measurement of the pressure when the ventricles contract) is 120 and the diastolic number (the measurement of the pressure when the heart relaxes) is 80. One of the main problems with too high a blood pressure—from the narrowing of the arteries because of either the buildup of fatty deposits on the walls or plaque—is that it can cause serious damage to the heart and blood vessels. Such damage can not only cause the heart to lose its ability to pump well, but it can also cause blood vessels to lose their elasticity and ability to carry blood efficiently.


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