1. Galen thought the heart was a heater that warmed the blood
In the middle ages, scholars felt that the Holy Spirit delivered air through the arteries and veins.
William Harvery is credited with modern ideas of circulation.

5. Measure of Heart Performance
EKG Measures the electrical activity of the heart
Blood Pressure indicates the strength of heart contraction and the resistance to blood flow

6. The Electrocardiogram

7. Blood Pressure
Systolic Pressure ( 120 mm Hg) is caused by contraction of the ventricles
Diastolic Pressure (80 mm Hg) is the pressure when the heart is completely relaxed
Arterial resistance to blood flow may raise blood pressure