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The Circulatory System. Introduction. The circulatory (or cardiovascular ) system is the transport system of the body and has four major functions: Transportation of O2 and CO2 Transportation of wastes and nutrients Transportation of hormones Maintain body temperature.
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Introduction • The circulatory (or cardiovascular) system is the transport system of the body and has four major functions: • Transportation of O2 and CO2 • Transportation of wastes and nutrients • Transportation of hormones • Maintain body temperature.
Structure of the Circulatory System • A circulatory system consists of three parts: • A fluid in which materials are transported (i.e. blood) • A system of vessels to transport the fluid all over the body (i.e. arteries and veins) • A pump (i.e. heart)
Interesting Facts • No cell in your body is more than two cells away from a blood vessel. • There are 96 000 km of blood vessels in your body to sustain your 100 trillion cells. • Your heart beats around 72 times a minute and in your lifetime it will pump enough blood to fill two ocean tankers!
Two Systems in One • The left and right side of your heart do different functions. • The right side of your heart pumps blood to the lungs to exchange CO2 for O2 in the pulmonary circuit. • The left side of your heart pumps oxygen rich blood around your body in the systemic circuit. • Blood moving through the heart is the cardiac circuit. Lungs
Heart Structure • The wall separating the left and right sides of your heart is known as the septum. • Each side has a thin walled atrium to collect blood above a more muscular ventricle that pumps blood. • Between the different regions of the heart are valves to ensure blood only flows in one direction.
Heart Sounds • The heart beat is actually controlled within the heart itself by two bundles of nerves. • The sinoatrial (SA) node acts as a pacemaker causing the atria to contract while the atrioventricular (AV) node ensures the ventricles contract a moment later.
Lub-dub • The sound we hear is caused by the closing of the heart valves. • The “lub” is from the shutting of the valves between the atria and ventricles when blood is moved from the top to the bottom of the heart. • The “dub” is the closing of the valves between the ventricles and the arteries that leave the heart.
Blood Vessels • Arteries carry blood away from the heart and have thicker walls to withstand the greater pressure of blood. • Veins take blood back to the heart and have valves to ensure one way blood flow. • Capillaries are the junction of arteries and veins where gases and nutrients are exchanged with body cells. Artery (from heart) Vein (to heart)
Homework • What are the four functions of a circulatory system? • What are the three main parts to a circulatory system? • What are two differences between an Atrium and a Ventricle? • Using three different points of criteria, compare arteries, veins and capillaries.