left ventricle
The lower left chamber of the heart is called the left ventricle. It is thick and muscular hence manifests a stronger heart beat.
there are four chambers in the heart. two are atriums and two are ventricles
The muscle of a sheep's heart is thick for the same reason our heart muscle is thick. It is thick as it has to pump blood around the body, and so it is under a lot of pressure.
very thick
The muscle walls of the heart are called the myocardium. This thick, muscular layer is responsible for the heart's contraction and pumping action. It is located between the inner layer, the endocardium, and the outer layer, the epicardium, which together form the heart's structure. The myocardium varies in thickness depending on the heart chamber, being most prominent in the ventricles.
The particle that leaves a short, thick trail in a cloud chamber is likely an alpha particle. Alpha particles are positively charged and relatively heavy, which causes them to ionize the gas molecules in the chamber, creating a dense trail.
Your heart has four chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles. The left ventricle is the largest and strongest chamber in your heart. The left ventricle's chamber walls are only about a half-inch thick, but they have enough force to push blood through the aortic valve and into your body.Source: Texas Heart Institute
you
Compare to the width of an atom, yes
In physiological conditions both heart chambers pump equal amounts of blood. This is a natural consequence of the fact that it is a serial pumping system. Everything that passes through the right part must also pass through the left part.
two inches
It is thicker than 1/8th inch thick steel.