<span>The upper chamber is called an atrium (or auricle), and the lower chamber is called a ventricle. The two atria act as receiving chambers for blood entering the heart; the more muscular ventricles pump the blood out of the heart.</span>
Smallpox is the only human disease to have been eradicated by vaccination. The last case was in <span>Somalia in 1977 and was successfully eradicated. Now we have been smallpox free for 30 years!</span>
