Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
The left ventricle is one of four chambers (two atria and two ventricles) in the human heart. It receives oxygenated blood from the left atrium via the mitral valve, and pumps it into the aorta via the aortic valve.
The left ventricle is longer and more conical in shape than the right, and on transverse section its concavity presents an oval or nearly circular outline. It forms a small part of the sternocostal surface and a considerable part of the diaphragmatic surface of the heart; it also forms the apex of the heart.
By teenage and adult ages, its walls have thickened to three to six times greater than that of the right ventricle. This reflects the typical five times greater pressure workload this chamber performs while accepting blood returning from the lungs veins at ~8mmHg pressure and pushing it forward to the typical ~120mmHg pressure in the aorta during each heartbeat. (The pressures stated are resting values and stated as relative to surrounding atmospheric which is the typical "0" reference pressure used in medicine.)
For excellence of health, the left ventricular muscle must:
- (a) relax very rapidly after each contraction so as to fill rapidly with oxygenated blood flowing from the lung veins, i.e. diastolic relaxation and filling.
- (b) contract rapidly and forcibly to force the majority of this blood into the aorta, overcoming the much higher aortic pressure and the extra pressure required to stretch the aorta and other major arteries enough to expand and make room for the sudden increase in blood volume, i.e. systolic contraction and ejection.
- (c) be able to rapidly increase or decrease its pumping capacity under nervous system control.
Typical healthy adult heart pumping volume is ~5 liters/min, resting. Maximum capacity pumping volume extends from ~25 liters/min for non-athletes to as high as ~45 liters/min for Olympic level athletes.