Asker's rating. 1  Fred is correct the smaller the number the bigger the metal. 2  12 gauge is thinner than 7 gauge. 3  The gague refers to the thickness of the metal in question. the issue of strenght is really determines by the type of metal, not necessarily it's thickness.
The left ventricle pumps oxygen-rich blood out of the heart and into an artery called the aorta. From the aorta, blood branches out into a series of ever smaller tube-like vessels: arteries, arterioles and finally capillaries. The capillaries deliver the blood's oxygen and nutrients to cells.
From there the blood enters the pulmonary artery and end up in the lungs. After it gets oxygen rich, the blood is sent back to the heart through the pulmonary veins. The blood is dumped into the left atrium and there is another special valve between the left atrium and the left ventricle. The valve closes down so that the blood doesn't go back to the atrium when it squeezes.