The human body holds appx. 1.2-1.5 gallons of blood, the human heart holds and pumps each beat appx. 2-3 oz.
When the heart pumps the blood out of its left side, it goes out a main artery to different branch arteries to smaller branch arteries, it enters all the different organs and as it's there transfers oxygen and other nutrients to the organs, and picks up some of the crap the organ is getting rid of. As it makes its way through, it gets to the veins where it hitches a ride back into the right side of the heart, from there it gets pumped into the pulmonary artery ( fun fact, only artery in the body that carries unoxygenated blood ) and ends up in the lungs to get reoxygenated, then to the pulmonary vein ( see last fun fact, same concept ) where it lands back in the left side of the heart to be pumped back out in the blood.
I'm pretty sure this takes about 1 minute round trip, wit 60 beats in a minute average. Your circulatory system is essentially like one big conveyor belt going in 2 circles. The only thing it gets "jammed" in would be plaque built up on the artery walls, when this happens, it's like when you put your finger on a hose and the water speeds up to try to compete for the smaller diameter. When that gets too clogged, is when you get loss of blood flow to that area. Strike, heart attack, necrosis of extremities...