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The Transport System

The Transport System . IB topic 6.2. The transport system . Mammals have a closed circulation Blood is pumped by the heart and circulated in a continuous system of arteries, veins, and capillaries Under pressure The heart has four chambers The heart is divided into right and left sides

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The Transport System

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  1. The Transport System IB topic 6.2

  2. The transport system • Mammals have a closed circulation • Blood is pumped by the heart and circulated in a continuous system of arteries, veins, and capillaries • Under pressure • The heart has four chambers • The heart is divided into right and left sides • Blood flows from the right side of the heart to the lungs, then back to the left side of the heart • From here, it is pumped around the rest of the body and back to the right side of the heart • Blood passes twice through the heart in every single circulation of the body (double circulation)

  3. Features of the circulatory system • Advantages in mammalian circulation: • Simultaneous high pressure delivery of oxygenated blood to all regions of the body • Oxygenated blood reaches respiring tissues

  4. Blood • Blood is tissue • Consists of: • Liquid medium called plasma • Erythrocytes (RBC) • Involved in transport of respiratory gases (O2, CO2) • Leucocytes (WBC) • Combat infection • Lymphocytes • Form antibodies • Phagocytes • Ingest bacteria or cell fragments • Platelets • Blood clotting mechanism

  5. Blood break-down • Blood is: • 55% plasma • Plasma is: • 90% water • 10% dissolved substances (proteins, salts, lipids) • 45% cells • RBC, WBC, platelets

  6. Blood transports … • Nutrients • Oxygen • Carbon dioxide • Hormones • Antibodies • Urea • Heat

  7. The plumbing of the circulation system • There are three types of vessels: • Arteries: carry blood away from the heart • Veins: carry blood back to the heart • Capillaries: fine networks linking arteries and veins • Both arteries and veins have strong, elastic walls • Arteries are very much thicker and stronger • Strength: collagen • Elastic: smooth muscle fibers • Capillaries • Endothelium (inner layer) • Branch • No cell is far from a capillary

  8. Why the differences? • Blood leaving the heart is under high pressure • Thick arteries • By the time blood reaches the capillaries , the pressure has decreased greatly • Thinner capillaries and veins • Also, low pressure may mean backflow, which is why veins have valves • Valves are opened by blood pressure from behind

  9. Differences

  10. The arrangement of arteries and veins • The right side • Pumps deoxygenated blood to the lungs • Arteries, veins, capillaries = pulmonary circulation • The left side • Pumps oxygenated blood to the rest of the body • Arteries, veins, capillaries = systemic circulation • Aorta (artery)

  11. Process • The branching sequence of circulation: • Aorta  artery  arteriole  capillary  venule  vein  vena cava • Vena cava carries blood back to the heart

  12. The Heart • About the size of a clenched fist

  13. The heart as a pump Divided into 4 chambers • Upper: thin walled atria (atrium = singular) • Receive blood into the heart • Lower: thick walled ventricles • The left is much thicker than the right • The volumes are identical • Pump blood out of the heart • You should know the flow of blood

  14. The heart as a pump • Coronary arteries supply the walls of the heart with oxygenated blood • Valves prevent backflow • Atrio-ventricular valves prevent backflow from ventricles to atria • Right side: tricuspid valve • Left side: bicuspid or mitral valve • Tendons are attached to prevent folding back • Semi-lunar valves separates the ventricles from pulmonary artery (right side) and aorta (left side)

  15. Animations • http://www.nhlbi.nih.gov/health/health-topics/topics/hhw/contraction.html • Penn health cardiology and cardiac surgery • http://www.pennhealth.com/health_info/animationplayer/

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