After the Russian Revolution of 1917, Georgia declared independence in 1918, but the democratic Republic of Georgia, ruled by a social-democratic government, was invaded by the Red Army in 1921, a few days after it was recognized by European states.
And.. The Semilunar Valves prevent the back flow of the blood from the arteries to the ventricles. Explain what happens to tissues, such as the heart, or the brain, if oxygenated blood is not delivered in a timely manner. The tissue of the organ starts to die.
These are the arteries responsible for supplying your heart with blood. Why doesn't the heart act like an opportunist and just take its oxygen straight from the blood that's constantly passing through its chambers? There are two important reasons. First, not all of the blood in the heart has oxygen.