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.
Another example in humans and some other animals is after an acute myocardial infarction (heart attack). Collateral circulation in the heart tissue will sometimes bypass the blockage in the main artery and supply enough oxygenated blood to enable the cardiac tissue to survive and recover.