Left Ventricle.
Out of the four chambers in the human heart, the left ventricle is the lower chamber on the left side of the heart. It is separated from the right ventricle by the interventricular septum which is muscular partition also consisting of connective tissue.
The left ventricle of the heart dilates to receive oxygenated blood from the left atrium through the mitral valve (diastole) and contracts to pump this blood into the aorta through the aortic valve (systole) for supply to all parts of the body through a network of arteries, arterioles and capillaries.
The valves of the heart play an important role in maintaining the sequence of blood flow. During diastole, the mitral valve opens to allow blood to flow from the left atrium to the left ventricle. The aortic valve is closed during this phase to allow the left ventricle to fill with blood. At systole (contraction of ventricles), the aortic valve opens while the mitral valve closes. This ensures that blood flows from the left ventricle of the heart into the aorta and not backwards into the left atrium.
The mitral valve, which is also called the bicuspid valve (because it has two cusps) is anchored to the wall of the left ventricle by the papillary muscle which is, in turn attached to the mitral valve by cord like structures called the chordae tendinae. This attachment prevents the mitral valve from prolapsing into the left atrium when the left ventricle contracts.
Picture of left ventricle.
Click on image to enlarge.
Shape of Left Ventricle.
The left ventricle is conical in shape and shorter than the right ventricle. When cut in transverse section, it presents an almost circular outline.
Size of the Left Ventricle.
The left ventricle of the heart is the largest chamber of the heart. It is more muscular and thicker than the right ventricle ( three to six times thicker) because it has to pump blood at a greater pressure through the aorta and its network of arteries to all parts of the body, including the walls of the heart via the coronary arteries.
It occupies most of the anterior and left lateral surfaces of the heart. Most of the heart’s apex too is occupied by the left ventricle.
Left Ventricle Wall Thickness. The wall of the left ventricle is 8 to 15 mm thick but can be only 2 mm at the tip of the apex.
Pressure of Blood in Left Ventricle.
During diastole (relaxation of left ventricle), the pressure of blood returning from the pulmonary veins is 80 mm of Hg while at systole it is 120 mm of Hg. These are the pressures seen when the person is at rest. Hence the reference to normal blood pressure which is stated as 120/80 mm of Hg, where 120 is the systolic and 80 is the diastolic blood pressure.
Pumping Volume of Left Ventricle.
The pumping volume is the volume of blood pumped by the heart per minute.
- During rest in a normal adult, the pumping volume of the heart is 5 liters per minute.
- At its maximum, the normal heart can pump 25 liters per minute when required in a non athlete.
- In professional athletes of the highest standard, as in Olympians, the heart pumps as much as 45 liters per minute during strenuous physical activity.
Stroke Volume of Left Ventricle.
Stroke volume refers to the volume of blood pumped out of the ventricle during each beat. It can apply to each of the ventricles but is more widely used to in reference to left ventricle. It is measured from readings taken with the help of an electrocardiogram (ECG). The stroke volume of both the ventricles is generally equal – approximately 70 ml – in a normal healthy adult weighing about 60 to 70 kg. It is one of the important aspects to be examined of the cardiovascular system.
Function of Left Ventricle.
- Dilates very rapidly to receive oxygenated blood from the left atrium during diastole.
- Contracts rapidly with great force during systole to pump blood into the aorta with enough pressure to force the blood through the network of arteries, arterioles and capillaries to all parts of the body. It has to do this by overcoming the pressure in the aorta and the major arteries.
- Be able to increase or reduce pumping volume as required as at times of rest, stress and physical activity.
Blood Supply of Left Ventricle.
Blood supply of the left ventricle is shared by the left and right main coronary arteries.
Your action step.
If you feel this article could be useful, do share it on social media and pass a comment below.
Medic On WebRelated posts: