This extrapolates to some 30 million men in the U.S. alone and 100 million men worldwide who have this problem. What is not well appreciated is the link between ED and other medical conditions.
Erection is a hydraulic event.
Blood flows into these cylinders and causes rigidity when it is trapped and high pressure develops. The key event in the development of an erection is relaxation of the smooth muscle inside the erectile cylinder. Loss of rigidity is dependent upon the contraction of the muscle in the erectile bodies. As this muscle contracts, the size of the spaces shrink, allowing the drainage veins to open, which results in loss of rigidity. This process is under adrenaline control.