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Approximately 500,000 babies are born each year in the United States to teenage mothers.
Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.
When blood is deoxygenated and flowing back to the heart through the veins, it is dark reddish-blue in color. Blood in the arteries that is oxygenated and flowing out to the body is bright red. Whereas arterial blood comes out in spurts, venous blood flows.
The ratio of hydrogen atoms to oxygen in water (H2O) is 2:1.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.