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E.Circulate - Circulation Circulatory Systems Cardio...

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Circulation Heyer 1 Circulatory Systems • Cardio vascular System –Heart & Vessels –(Pumps & Pipes) • Lymphatic System Circulatory Systems Functions: • Transportation – Water & electrolytes (salts) – Dissolved gases— O 2 & CO 2 – Nutrients – Wastes – Chemical messengers (hormones) – Defense (immune) systems – Repair (clotting) factors • Thermoregulation • Hydraulics Open Versus Closed Systems “Open”: blood flow in open- ended vessels “Closed”: blood stays within vessels Circulatory system in insect and earthworm Mammalian CV System Closed, Two circuit system Pulmonary : blood to and from lungs Systemic : blood to and from body Heart is a 2-sided pump CV system of a mammal Human Heart Anatomy Diagrams show heart from front – Viewer’s “right” is heart’s “left” Enclosed in fluid- filled sac behind sternum Human heart in chest cavity Heart Anatomy (cont.) Like all organs, the heart is constructed of many tissues
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Circulation Heyer 2 Heart Anatomy (cont.) 4 chambers – 2 thin-walled Atria , 2 thick-walled Ventricles 4 valves – 2 AV valves, 2 SL valves – Valves keep blood moving in one direction Cardiac Contractions 1. Sinus node (pacemaker) fires 2. Signal spreads across atria 3. Cardiac muscle in atria contract 4. Signal reaches AV node; travels down Bundle of HIS to apex of heart 5. Signal spreads across venticles 6. Cardiac muscle in venticles contract The Beat of The Heart The cardiac cycle • Diastole Blood flows from the veins into the heart chambers • Systole The atria briefly contract and fill the ventricles with blood Then the ventricles contract and propel blood out Heart is relaxed. AV valves are open. 1 3 Atria contract. Ventricles contract. Semilunar valves are open. 0.4 sec 0.1 sec 0.3 sec 2 DIASTOLE SYSTOLE 1 Heart Sounds Sound: “lub-dupp, lub-dupp” Sounds are vibrations from turbulent flow caused by the closing valves. “Lub”: ventricles contract and AV valves slam shut — beginning of systole “Dupp”: atria contract and SL valves slam shut — ending of systole Heart murmur : hissing of blood squirting backward thru valve or a patent aperture. Vessel Adaptations Arteries blood away from heart Thick-walled and elastic to withstand higher pressure Veins blood toward heart Internal valves prevent backflow Capillaries - thin-walled and highly branched Only 1 cell thick to maximize diffusion rates Blood vessel structure Path of blood flow through the heart 1.
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