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Circulation. 18.1. Your Cardiovascular System Distributes materials Includes heart, blood, kilometers of vessels Closed system Diffusion Your Heart Cardiac muscle Behind sternum, between lungs Four cavities Atria – two upper chambers Ventricles – two lower chambers
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Circulation 18.1
Your Cardiovascular System • Distributes materials • Includes heart, blood, kilometers of vessels • Closed system • Diffusion • Your Heart • Cardiac muscle • Behind sternum, between lungs • Four cavities • Atria – two upper chambers • Ventricles – two lower chambers • Contracts in atria, and in ventricles. Valve and walls separating
Pulmonary Circulation • Pulmonary circulation – flow of blood through the heart to the lungs and back to the heart. • Systemic Circulation • Systemic circulation – moves oxygen rich blood to all organs and body tissues except for the heart and lungs • Coronary Circulation • Coronary Circulation – flow of blood to the tissues of the heart. • Blockage results in heart attack. • Blood Vessels • Types of Blood Vessels • Arteries – blood vessels that move away from the heart • Veins – blood vessels that move blood to the heart • Capillaries – microscopic blood vessels that connect arteries and veins
Blood Pressure • Blood pressure - force blood exerts on the walls of the vessels. • Highest in arteries • Felt as pulse – normal rate 65 -80 beats per minute. • Measures in large arteries by two numbers • Top number – measure of pressure when the ventricles contract and blood is pushed out of the heart • Lower number – measures of the pressure when the ventricles are filling up, just before they contract again. • The Big Push • Pressure = Force/Area (P = F/A) • Pressure Measurement • Top = Systolic pressure • Bottom = Diastolic pressure • Average young adult = 120/80
Control of Blood Pressure • Nerve cells in walls allow for change • Cardiovascular Disease • Heart disease is the major cause of death in the US • Atherosclerosis – fatty deposits on the arterial walls • Hypertension – high blood pressure • Smoking and stress Pg. 500 1-3