Chapter 8 Transport in Humans Lesson 2 - Types of blood vessels


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  • Blood pressure and blood velocity drop off in capillaries because capillaries have a greater cross-sectional area than arteries.
  • Chapter 8 Transport in Humans Lesson 2 - Types of blood vessels

    1. 1. 2) Blood vessels
    2. 2. Blood vessels arteries capillaries veins <ul><li>carry blood away from heart </li></ul><ul><li>connect arteries to veins </li></ul><ul><li>exchange materials with body tissues </li></ul><ul><li>return blood to heart </li></ul>Venule Arteriole Types of blood vessels Vein Capillary Artery Heart
    3. 3. Cross-sectional area as it relates to blood pressure and velocity
    4. 4. Arteries <ul><li>carries oxygenated blood (except pulmonary artery and umbilical artery) </li></ul><ul><li>blood transport from heart to organs </li></ul><ul><li>Thick, muscular, elastic </li></ul><ul><li>high pressure </li></ul><ul><li>small lumen </li></ul><ul><li>no valves </li></ul>
    5. 5. Veins <ul><li>Carries deoxygenated blood </li></ul><ul><li>Blood transport from organs to heart </li></ul><ul><li>Thin, less muscular </li></ul><ul><li>Low pressure </li></ul><ul><li>Large lumen </li></ul><ul><li>valves within them to prevent backflow of blood </li></ul>
    6. 6. Veins
    7. 7. Blood flow in veins muscles beside vein contract action of valves blood flows towards heart muscle (contract) valve flaps pushed apart by blood pressure vein is squeezed by muscles valve flaps pushed together by backflow of blood
    8. 8. Differences between Artery & Vein <ul><li>thick & </li></ul><ul><li>elastic wall </li></ul><ul><li>small lumen </li></ul><ul><li>no valves </li></ul><ul><li>thin wall </li></ul><ul><li>large lumen </li></ul><ul><li>valves are </li></ul><ul><li>present </li></ul>Vein Artery
    9. 9. Comparison of artery and vein artery vein <ul><li>thick muscular wall of the artery to the vein </li></ul><ul><li>lumen of the vein is slightly larger and commonly holds more blood </li></ul>
    10. 10. Artery vs veins:
    11. 11. Comparison of arteries and veins
    12. 12. Capillary
    13. 13. Capillaries <ul><li>allow exchange of materials between the blood and the body tissues </li></ul>arterioles capillaries venules <ul><li>the wall is thin & permeable to O 2 , CO 2 , glucose, water ... etc. </li></ul>O 2 , nutrients CO 2 , waste 3-dimensional diagram of capillary
    14. 14. Capillary network <ul><li>Site of exchange of gases, nutrients and wastes </li></ul><ul><li>Walls are one cell thick </li></ul><ul><li>Great length of capillaries throughout body </li></ul><ul><li>Immense surface area for exchange of materials </li></ul><ul><li>Exchange between blood in capillary and surrounding tissue/interstitial fluid </li></ul>
    15. 15. Exchange of Materials between Capillaries and Tissue Cells <ul><li>Colourless liquid between minute spaces of tissue cells = tissue fluid </li></ul><ul><li>Cells are bathed by the tissue fluid which carries in solution dissolved food substances and O 2 </li></ul><ul><li>These dissolved substances diffuse into the tissue cells </li></ul><ul><li>Waste products diffuse from cells into the tissue fluid and then through the capillary walls into the blood and to the excretory organs for removal </li></ul>
    16. 16. Exchange of materials between the blood and the body cells plasma tissue fluid O 2 nutrients water white blood cells Diffuse across the capillary wall CO 2 waste products Diffuse across the capillary wall Squeeze through the wall oxyhaemoglobin capillary cell
    17. 17. Capillaries <ul><li>Narrow -> RBCs move in a single file through the lumen of capillaries </li></ul><ul><li>RBCs may become bell-shaped when they pass through the lumen of capillaries </li></ul><ul><li>Advantages : </li></ul><ul><li>Diameter of the RBC is decreased (pass through lumen of capillaries easily) </li></ul><ul><li>Increases s.a. to speed up absorption/ release of O 2 </li></ul><ul><li>Rate of blood flow is reduced -> increase efficiency of gaseous exchange (more time) </li></ul>
    18. 18. Formation of the tissue fluid At arterial end : some materials are forced out of the capillaries high pressure capillary bed body cell red blood cell blood pressure  pressure of tissue fluid tissue fluid arteriole tissue fluid
    19. 19. Formation of the tissue fluid Tissue fluid is mainly water with some mineral salts, fats, sugars and hormones similar to blood plasma but NO plasma proteins and red blood cells too large to be forced through capillary wall capillary bed tissue fluid
    20. 20. Formation of the tissue fluid At venous end : some tissue fluid return to capillaries , others are drained into lymph vessels capillary bed blood pressure  pressure of tissue fluid venule lymph
    21. 21. How does exchange take place?
    22. 22. Activity: In your groups, come out with a table stating the characteristics of the artery, vein and capillary Use the following table as a template Template Answer