The Circulatory SystemTransport Absorption Involves the passage of materials into and out of the blood stream. Circulation Distribution of materials through out the body. Transport Is the process of absorption and circulation of materials throughout the body. The Heart • The human heart is a muscle. • It has 4 chambers. • It pumps blood. Anatomy of the heart • The heart has 2 atria (upper chambers). • Both atria have very thin walls used to hold the blood (waiting room). • The heart has 2 ventricles (lower chambers). • The ventricles have very thick walls (blood is pumped here). Valves • The chambers of the heart are separated by valves. • The valves prevent the flow of blood backwards. The Pericardium The heart is covered by a thin, tough sac called the pericardium. Pulmonary circulation Involves blood flow from the right ventricle to the lungs where it picks up oxygen and loses carbon dioxide and then returns to the left atrium. Systemic circulation • Blood flows from the left ventricle to all body parts and returns to the heart. • This blood does not flow through the lungs. Let’s go to the Video! QuickTime™ and a Sorenson Video 3 decompressor are needed to see this picture.