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Flashcards · Biology · Blood, Blood Vessels and the Heart

Arteries, Veins and Capillaries

22 cards

  1. Which direction does blood flow in arteries?

    Away from the heart.

  2. Which direction does blood flow in veins?

    Towards the heart.

  3. What is the function of capillaries?

    To allow substances to be exchanged between the blood and the cells.

  4. Why do arteries have thick walls?

    To withstand the high pressure of the blood from the heart.

  5. What do the elastic fibres in an artery do?

    They stretch and recoil to smooth the flow and keep the pressure up.

  6. What is the lumen?

    The space inside a blood vessel.

  7. Why is the lumen of an artery narrow?

    It helps to keep the pressure high.

  8. Why do veins have a wide lumen?

    The blood has little resistance, so it flows easily at low pressure.

  9. Why do veins have valves?

    To stop the blood flowing backwards.

  10. What helps to push blood along the veins in the legs?

    The squeezing of the leg muscles.

  11. Why are capillary walls one cell thick?

    So that the diffusion distance is very short.

  12. Why are capillaries so narrow?

    Red blood cells pass through in single file, close to the wall, so oxygen exchange is fast.

  13. Why does the blood flow slowly through the capillaries?

    The total space in the capillary network is large. It gives time for exchange.

  14. Which artery carries deoxygenated blood?

    The pulmonary artery, to the lungs.

  15. Which vein carries oxygenated blood?

    The pulmonary vein, from the lungs.

  16. What is your pulse?

    The stretching and recoil of an artery wall with each heartbeat.

  17. How do you calculate the rate of blood flow?

    Volume of blood divided by the time.

  18. A vessel image is 40 mm across at \(\times 8\) magnification. What is the actual size?

    \(40 \div 8 = 5\ \text{mm}\).

  19. Why does a cut artery spurt but a cut vein ooze?

    Arteries have high pressure and pulse with the heartbeat. Veins have low pressure.

  20. What is the usual mistake with arteries and veins?

    Saying arteries carry oxygenated blood and veins deoxygenated. It is the direction of flow that matters.

  21. Three blood vessels cut lengthways, with no labels. Name the three vessels in this diagram, and say how each is adapted. The same three vessels labelled artery, capillary and vein, with their features.

    Top is an artery with a thick muscular, elastic wall and a narrow lumen for high pressure. Middle is a capillary, with a wall one cell thick for fast exchange. Bottom is a vein, with a thin wall, a wide lumen and a valve to stop backflow.

  22. Cross-sections of an artery and a vein with measurements. Calculate the actual lumen diameter of the artery.

    Actual size equals image size divided by magnification, so \(22 \div 10 = 2.2\ \text{mm}\).