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Elderly adults are living longer, and causes of death are shifting. At the same time, autopsy rates are at or near their lowest in history.
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.
Not getting enough sleep can greatly weaken the immune system. Lack of sleep makes you more likely to catch a cold, or more difficult to fight off an infection.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Malaria was not eliminated in the United States until 1951. The term eliminated means that no new cases arise in a country for 3 years.