Transcript 16-1Cardio
The Body’s Transportation System Our Cardiovascular System Its Parts The cardiovascular system (or circulatory system) consists of three parts: 1.)the heart, 2.)blood vessels, and 3.)blood. The 2 Main Functions of the Cardiovascular system A.) The cardiovascular system’s bloodstream carries needed materials to cells. For example, blood carries oxygen from the lungs to your body cells. Remember the nutrients from the digestive system are absorbed into blood vessel-filled villi lining the small intestine. These nutrients are then carried in the blood throughout the body to wherever they are needed. The Cardiovasc. Systems Functions (cont.) B.) The cardiovascular system also picks up waste products from cells and delivers them to places where they can be eliminated. For example, when cells use glucose for energy they produce CO2 as a waste product. This CO2 is then carried by the blood to the lungs where it is eliminated as you exhale. Cardio syst. Functions (cont) The cardiovascular system also transports cells that attack diseasecausing organisms. These can help you from becoming sick and if you do get sick,these disease-fighting blood cells will kill the disease-causing microorganisms to help you get well. The Heart The heart is a hollow muscular organ that's main job is to pump blood throughout the body. Each time it beats it pushes blood. The force it exerts pushing blood creates your blood pressure. It is made of cardiac muscle which can contract without getting tired. It may beat over 3 billion times over the course of your lifespan!!!! The Heart (cont…._) Its Structure: The heart has 4 chambers. It is divided into two sides and each side has 2 chambers-an upper and lower. The upper chambers (each is called an atrium), receive blood that comes into the heart. The two lower chambers (called ventricles) pump blood out of the heart. How the Heart Works The action of the heart works in two phases. In the 1st phase, heart muscle relaxes and the atria fill with blood. In the second phase, the atria contract, pushing blood through the heart valves to fill the ventricles. Then the ventricles contract (which closes the valves between the atria and ventricles) pumping blood out of the heart and through large blood vessels. A small group of cells called the Pacemaker (located in the right atrium), send out electrical signals that tell the heart when to contract, regulating your heart rate. For example, the pacemaker is constantly getting messages about the body’s oxygen needs. Exercise causes you to use up oxygen so your body sends messages to the pacemaker to increase the heart rate so that oxygenated blood reaches body cells faster. Blood Vessels and Circulation The body has three different kinds of blood vessels. 1.) Arteries: which carry blood away from the heart. From the arteries, blood flows into tiny blood vessels called 2.) Capillaries where substances like nutrients, O2, and wastes are exchanged between blood and body cells. Then blood flows into larger vessels called 3.) Veins, which carry blood back to the heart. Blood Vessels and Circulation (cont…) In our bodies, blood flows in two loops. In the 1st loop, the heart’s right atrium pumps O2-poor blood into the right ventricle which then pumps blood into an artery taking blood to the capillaries that fill the lungs (where it picks up O2 and gets rid of CO2) then into veins that carry oxygenated blood to the heart (into the left atrium). Blood Vessels and Circulation (cont…) In the 2nd loop, the left atrium pumps oxygenated blood into the left ventricle which then pumps it into the aorta (the largest artery). From the aorta blood flows into smaller branching arteries that take it throughout the body to capillaries where it delivers things the body needs (like nutrients, O2) and picks up wastes. Then, the blood returns through veins again to the heart (ending up in the right atrium) completing the 2nd loop.