Why is the wall in the left ventricles thicker?

Answer 1

The left and right atria are thinner walled receiving chambers of the heart where blood returns to the heart via the great veins. The two inferior chambers, the left and right ventricles, are the pumps that eject the blood into the arteries and keep it flowing through the body. If you picture it like your hands it might help. Picture holding both hands out, and in one hand you have a cup of water (atria), and in the other hand you have a squeeze pump that you constantly have to squeeze to move that water (ventricles). That hand with the pump will eventually become stronger (and therefore bigger/thicker) than the hand that is simply holding the water because of the muscle activity. So it makes sense that the atrium has some muscle, but not nearly as much as ventricles because the ventricles are acting as the pump. :-)

Answer 2

The left ventricle has to pump blood to the entire body, while the right ventricle only has to pump blood to the lungs, which requires less force. Therefore, the left ventricular wall is more muscular to provide a more powerful "push" to the systemic circulation.

Answer 3

The walls of the ventricles are made up of myocardium (heart muscle tissue), while the walls of the aorta and other arteries are made up of simpler, layered epithelium. The ventricles (along with the atria) are responsible for the pumping action of blood throughout the body, and are made up of pectinate muscles which contract when they receive the proper signal from the SV and AV nodes. They are also 'ground zero' as far as the pressurization of the cardiovascular system, so the walls need to be thick, strong and muscular to handle the high pressure of pumping blood. The Aorta, on the other hand, does not pump any blood and is only a vessel for transporting oxygenated blood to the rest of the body. It is still much thicker than the veins which enter the heart because, by the time the blood is coming back into the heart, it is essentially the furthest it can be from the pumping action, so the intravascular pressure is at it lowest, and therefore the vein walls don't need to be very thick at all.

Answer 4

The right ventricle pumps blood to the lungs which requires a lower pressure, so its walls are thinner than the left ventricle which must pump the blood to the rest of the body.