Question
A vein has a large lumen (the space inside the blood vessel that the blood flows through). What effect does this have? Allows large molecules to flow through the veins Allows blood to flow in multiple directions Causes the blood to flow at low pressures Allows substances to pass out of the veins
Answer
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Eliza
Veteran · Tutor for 9 years
Answer
Q6: Causes the blood to flow at low pressuresQ7: The blood vessel has a higher resistance to blood flow
Explanation
## Step 1:For Q6, a vein's large lumen primarily allows blood to flow at lower pressures. This is because the large space reduces the resistance against the blood flow, allowing it to flow more freely and at lower pressures. The other options are incorrect because veins do not allow blood to flow in multiple directions, they do not specifically allow large molecules to flow through, and the lumen size does not directly affect the passage of substances out of the veins.## Step 2:For Q7, according to the principles of fluid dynamics, the resistance to flow is directly proportional to the length of the vessel. So, when the length of a blood vessel increases, the resistance to blood flow also increases, leading to a decrease in blood flow. Therefore, the correct answer is that the blood vessel has a higher resistance to blood flow. The other options are incorrect because the width of the blood vessel is not mentioned in the question, and an increase in length does not necessarily mean the blood vessel has become narrower or wider.