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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.
Every 10 seconds, a person in the United States goes to the emergency room complaining of head pain. About 1.2 million visits are for acute migraine attacks.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Sildenafil (Viagra®) has two actions that may be of consequence in patients with heart disease. It can lower the blood pressure, and it can interact with nitrates. It should never be used in patients who are taking nitrates.
Oliver Wendell Holmes is credited with introducing the words "anesthesia" and "anesthetic" into the English language in 1846.