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Circulation and Gas Exchange

Circulation and Gas Exchange. Chapter 42. Internal Transport. Gastrovascular cavity makes circulatory system unnecessary Open and closed circulatory systems What are the limits an open circulatory system places on an organism? What is the difference between an artery and a vein?

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Circulation and Gas Exchange

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  1. Circulation and Gas Exchange Chapter 42

  2. Internal Transport • Gastrovascular cavity makes circulatory system unnecessary • Open and closed circulatory systems • What are the limits an open circulatory system places on an organism? • What is the difference between an artery and a vein? • Arteries carry blood away from the heart • Veins bring blood back to the heart

  3. Why do veins have valves and arteries do not? • Veins move blood against gravity without benefit of the heart contraction • Blood flow: • Heart  arteries  arterioles  capillaries  venules  veins  heart • Which chamber of the heart receives the blood? • Which chamber pumps the blood?

  4. Vertebrate Circulatory Evolution • Fish have 2 chambered heart, one beat circuit: • 1 atrium • 1 ventricle • Amphibians have 3 chambered heart: • 2 atria • 1 ventricle • Reptiles have 3 – 4 chambered heart: • Septum keeps 2 parts of ventricles separate • Mammals and birds have 4 chambered heart!

  5. The Heart • Cardiac muscle • Atria have thin walls • Ventricles have thick and powerful walls • Systole = ventricular contraction blood is pumped • Diastole = ventricular filling • Lub dub = heart sounds opening and closing of the valves • Lub = contraction of ventricles (AV closing) • Dub = blood recoiling against Semi Lunar valves • Heart murmur = valve defect

  6. CO = cardiac output ; • Volume of blood pumped/ minute • SV = stroke volume: • Amount of blood pumped by L ventricle/contraction • CO is effected by heart rate and SV • Myogenic heart can regulate its own rhythm • SA node is the pacemaker of the heart

  7. Arteries and Veins • How do differences between arteries and veins reflect their different functions? • Artery wall is very thick to absorb pulsation from heart • Veins are wider in diameter and are not as muscular • Veins have valves • Capillaries have only single layer of endothelium

  8. Blood Pressure • The force that blood exerts against vessel walls • BP is greater in arteries than veins • Pulse is measure of BP • Exact BP is measured as systolic/diastolic pressures • Constricted blood vessels have higher BP than dilated vessels • In veins heart has little effect on BP • How, then does blood move in veins?

  9. Blood Flow Velocity

  10. Blood Flow Through Capillary Beds

  11. Capillary Movement of Fluids

  12. Lymphatic System • Lymphatic system returns lost blood to circulatory system • Lymph nodes filter the lymph • Help fight infection

  13. How can 1 heartbeat circulate blood through 2 capillary beds?

  14. What are the advantages and disadvantages of the amphibian circulatory system?

  15. Why do endotherms have the greatest need for a 4 chambered heart? Birds and mammals show convergent evolution of 4 chambered heart!

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