||This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. (January 2013)|
The heart, with cutaways, as viewed from the left side.
Left ventricle at lower left, cutaway shows some internal cavity detail.
|Latin||ventriculus sinister cordis|
|Artery||anterior interventricular branch of left coronary artery|
|Vein||posterior vein of the left ventricle|
|Precursor||primitive ventricle, bulbus cordis|
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 shorter 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. The left ventricle is thicker and more muscular than the right ventricle because it pumps blood at a higher pressure.
By teenage and adult age, 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 pulmonary veins at ~80mmHg pressure (equivalent to around 11 kPa) and pushing it forward to the typical ~120mmHg pressure (around 16.3 kPa) 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.