Over the last 20 years, there has been a 90% decrease in cases of hepatitis A and an 80% decrease in hepatitis B cases in the U.S. Health experts believe that immunization efforts have led to this drop in rates of infection.here are three common types of hepatitis caused by viruses: hepatitis A, hepatitis B, and hepatitis C. Vaccines have been developed that protect people from contracting hepatitis A and B. There is no vaccine for hepatitis C. Hepatitis A and hepatitis B can be spread from person to person, although in different ways.
The largest artery is the aorta, the main high-pressure pipeline connected to the heart's left ventricle. The aorta branches into a network of smaller arteries that extend throughout the body. The arteries' smaller branches are called arterioles and capillaries.ll rights reserved. The arteries are the blood vessels that deliver oxygen-rich blood from the heart to the tissues of the body. Each artery is a muscular tube lined by smooth tissue and has three layers: 1  The intima, the inner layer lined by a smooth tissue called endothelium.
The normal heart is made up of four parts: two atria on the top of the heart (right atrium and left atrium), and two ventricles (right ventricle and left ventricle), the muscular chambers on the bottom that provide the major power to pump blood.