IB Biology Transport System

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  • 1. Topic 5 Human Health & Physiology 5.2 The Transport System
  • 2.
    • Transport of blood in vertebrates is by a closed circulatory system (cardiovascular system: CVS).
    • The CVS includes:
    • 1. the heart
    • 2. blood vessels
    • 3 blood
  • 3. 1. The heart:
    • Mammals have a 4 chambered heart: 2 atria and 2 ventricles.
    • Atria receive blood from the body, under low pressure. They are made up of walls of thin muscle.
    • Ventricles have thick muscular walls for pumping blood away from the heart.
  • 4.
    • Valves in the heart prevent backflow of blood.
    • Between each chamber is an atrioventricular valve (AV) to prevent blood from the atrium and ventricle from mixing.
    • Semilunar valves (SV) are at the 2 exits of the heart to prevent backflow as well.
    Valves
  • 5. Figure 42.6 The cardiac cycle
  • 6. Figure 42.5 The mammalian heart: a closer look
  • 7.  
  • 8.  
  • 9.
    • The Right Atrium, receives "used blood" from the body. Blood will be pushed through the tricuspid valve to the
    • Right Ventricle, the chamber which will pump to the lungs through the pulmonic valve to the
    • Pulmonary Arteries, providing blood to both lungs. Blood is circulated through the lungs where carbon dioxide is removed and oxygen added. It returns through the
    Path of blood through the heart
  • 10.
    • Pulmonary Veins, which empty into the
    • Left Atrium, a chamber which will push the Mitral Valve open. Blood then passes into the
    • Left Ventricle. Although it doesn't always look like it in drawings done from this angle, this is the largest and most important chamber in the heart. It pumps to the rest of the body. As it pumps, the pressure will close the mitral valve and open the aortic valve, with blood passing through to the
    Path of blood through the heart
  • 11. Figure 42.3 Generalized circulatory schemes of vertebrates
  • 12. 2. Blood Vessels
    • 3 main
    • Arteries : carry oxygen rich blood away from the heart to other organs. Have thick walls to support the increased pressure of the blood.
  • 13. Aorta
    • The largest Artery in the body
    • Carries Oxygen-Rich Blood from the LEFT VENTRICLE to all parts of the body, EXCEPT THE LUNGS.
  • 14. Veins: .
    • Veins carry blood back to the heart. Have thin walls containing valves to prevent the back flow of blood, due to the lower pressure of blood in the veins.
  • 15. Muscle contraction
    • Pressure in veins is low, so veins depend on
    • nearby muscular contractions to move blood
    • along.
  • 16. Figure 42.8 The structure of blood vessels
  • 17.
    • Capillaries: microscopic vessles that carry blood from arterioles that penetrate each tissue. Capillaries converge into venules and the venules turn into veins .
  • 18. Walls of the 3 Blood Vessels
  • 19. Pulse
    • When you take your pulse, you feel (or hear) two changes in pressure.
    • The first sound is the closing of the AV’s ( systolic pressure), the “lub” sound the heart makes. The 2 nd sound is the closing of the SV’s ( diastolic pressure), the “dub” sound.
    • *A defect in the closing of either valve results in a heart murmur .
  • 20.
    • Pressure is sensed by receptors in the arteries and atria. Nerve messages from these sensors communicate conditions to the medulla in the brain stem. Signals from the medulla regulate blood pressure.
    • The sinoatrial node (SA) sets the rate at which the heart contracts.It is the heart’s natural pacemaker .
    Control of the Pacemaker * The heart muscle beats on it own (myogenic), due to Cardiac muscle. It speeds up or slows down by involuntary control
  • 21.
    • medulla will send out these signals according to information it receives from many sources via nerves:
    • 1. Carotid bodies and aortic bodies detecting oxygen levels.
    • 2. Carbon dioxide-pH detectors located in the medulla itself which is indirectly sensing the CO2-pH levels in the blood around the brain.
  • 22. Figure 42.7 The control of heart rhythm
  • 23. Figure 42.10 The interrelationship of blood flow velocity, cross-sectional area of blood vessels, and blood pressure
  • 24. Figure 42.11 Measurement of blood pressure (Layer 1)
  • 25. Figure 42.11 Measurement of blood pressure (Layer 2)
  • 26. Figure 42.11 Measurement of blood pressure (Layer 3)
  • 27. Figure 42.11 Measurement of blood pressure (Layer 4)
  • 28.
    • Blood ( Average Blood Volume: 4 to 6 liters.)
    • Blood composition:
      • 55% Plasma (containing water, salts, proteins, etc.)
      • 45% Cellular elements:
        • Red Blood Cells : 5-6 million RBCs/ml of blood. Contain hemoglobin to transport O 2 and CO 2 .
        • White Blood Cells : 5,000-10,000 WBCs/ml of blood. Play an essential role in immunity and defense.
        • Platelets : Cellular fragments. 250,000- 400,000/ml of blood. Important in blood clotting.
  • 29. Figure 42.14 The composition of mammalian blood
  • 30. Clotting
  • 31. Clotting
    • Clotting is the mechanism that blocks broken
    • blood vessels and prevents blood from being
    • lost in excess .
    • Mechanism
    • Platelets or damaged cells are stimulated to release a group of proteins called clotting factors. These clotting factors are released into the plasma at the wound site
  • 32. Clotting
    • b) Clotting factors activate the enzyme Thrombin from its inactive form prothrombin
    • c) Thrombin turns the soluble plasma protein fibrinogen into its insoluble fibrous form Fibrin
    • d) Fibrin binds together platelets and blood cells to form a solid 'plug' for the wound. This plug is called a clot
  • 33. Figure 42.15 Differentiation of blood cells