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Circulatory System

Circulatory System. Circulatory system consists of:. Heart Blood Vessels Blood. Closed System in Humans. Arteries, Arterioles, Capillaries, Venules , Veins. Heart. Artery. Vein. Capillary. Venule. Arteriole. Portal Vein. Has capillaries at both ends E.g. hepatic portal vein

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Circulatory System

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  1. Circulatory System

  2. Circulatory system consists of: • Heart • Blood Vessels • Blood

  3. Closed System in Humans

  4. Arteries, Arterioles, Capillaries, Venules, Veins

  5. Heart Artery Vein Capillary Venule Arteriole

  6. Portal Vein Has capillaries at both ends E.g. hepatic portal vein Carries: • glucose • amino acids • minerals from intestine to liver

  7. Structure of Arteries, Veins and Capillaries Thick muscular wall Thin wall Large lumen Small lumen Very thin wall

  8. Veins have Valves

  9. Double Circulatory System

  10. Heart Structure Pulmonary artery Aorta Pulmonary vein Vena cava Left Atrium Right Atrium Semilunar valve Tricuspid valve Right ventricle Left ventricle Septum Cardiac Muscle

  11. Valves

  12. Human Circulatory System

  13. Structure of Human CirculatorySystem

  14. Heart • Located in thoracic cavity: area inside rib cage • Contains strong double pump • Made of a special muscle which does not tire • Coronary artery supplies heart itself with blood

  15. Cardiac Cycle

  16. Systole and Diastole • Diastole: the filling phase of the heart with blood (the heart is relaxed) • Systole: the emptying phase when the heart muscles contract

  17. Pacemakers

  18. Pacemakers • Heartbeat can occur independently of the brain • Controlled by a small bundle of specialised tissue called pacemakers (SA and AV nodes) in the right atrium • Sinoatrial (SA) node sends out regular electrical impulses causing the atria to contract • It also stimulates the atrio-ventricular (AV) node • The AV node then stimulates the ventricles to contract

  19. What affects the pacemakers? • The pacemaker itself controls the heartbeat • Average rate = 75 beats per minute • But signals from the brain (via nerves) and hormones can change the rate at which it operates

  20. Factors that can increase the heart rate include: • Exercise • Temperature • Emotions and shock

  21. Factors that decrease the heart rate include: • Relaxation • Sleep • Alcohol

  22. Pulse What causes a pulse? The expansion of an artery due to the pumping of the heart What is blood pressure? • Recall : Pressure = Force/area • Blood pressure is the force exerted by blood on the wall of a blood vessel

  23. Effects of External Factors on Heart Rate

  24. To maintain a healthy heart • Don’t smoke • Eat less fat • Eat less salt • Exercise regularly • Avoid excess stress

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