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.
Humans need oxygen to provide nutrients to all of the cells in their bodies. If tissues and cells go without oxygen, then they begin to die quickly. For example, brain cells can only go without oxygen for three minutes before they begin to die. After three minutes of no oxygen, permanent brain damage begins to spread throughout the brain's tissues. The body also needs energy in order to function properly.