Ventricles have thicker muscles than the smaller chambers, the atria. As such, they can generate much higher blood pressure. Of the two, the left ventricle, which feeds the aorta, has the thicker wall. The thicker wall occurs in the developing fetus as, even at this stage, the left ventricle is doing more work. However, the capacity of each ventricle is roughly equal. The left ventricle is somewhat longer and has a conical shape.
The two ventricles are separated by the ventricular septum, which bulges slightly into the right ventricle.
The ventricles contract and relax faster than other muscle groups in the body in order to be able to beat quickly and in an co-ordinated fashion. At rest, the ventricles pump about 5 litres of blood a minute, which is about equal to the amount of blood in an average human body. However, at full capacity, the ventricles can pump 5 times as much blood a minute in an average person and an athlete's ventricles can pump up to nine times as much blood.This is despite the fact that the ventricles typically only pump about .1 litres of blood with each beat. At rest, a ventricle hols a little less than .15 litres of blood and when fully contracted, still holds about .05 litres.
Arrhythmia is almost always seen in the ventricles.