LEts investigate bp

Suppose our guess is - “Pipe with a narrow diameter will reduce the blood flow”

How can we test whether our guess is correct or not?
One way to check this is to do a small experiment-

For this you will require

• 2  buckets
• An old plastic bottle like a cold drink bottle, water bottle etc that can be easily pressed.
• Two pipes about 2 meters with different diameters

To do the experiment
1.  Fill one of the buckets with water. There should be enough water in the bucket to submerge the plastic bottle.
2.   Take the pipe and the plastic bottle and put one end of the pipe inside the bottle.
3.   Now put the plastic bottle and the pipe inside the bucket filled with water.
4.   Keep an empty bucket nearby.
5.   Take the free end of the pipe and hang it in the empty bucket.
6.   Now hold the plastic bottle with one hand. Make sure the bottle is inside the water.
7.   Squeeze the bottle repeatedly. You will see that water will start flowing from the pipe into the empty bucket.
This is how heart pumps blood into blood pipes which then carry the blood to different organs.
8.   Measure the water that flowed into the empty bucket in 1 minute.
9.   Repeat the procedure for second pipe with different diameter
10. Measure water that flowed into the empty bucket.

write down your observations in your note book.
 

Was the quantity of water pumped out more when you used the pipe with -
 smaller diameter
 larger diameter

Did your initial guess match with the result of our activity? What does it say about the effect of diameter of pipe on the flow of blood?

What will happen if the amount of blood pumped by the heart is the same but the diameter of the pipe becomes smaller?
Then the same amount of water will rush through the narrower pipe, thus increasing the pressure in the pipe.
Now, why does the blood pipe become narrow?
What are the conditions that can make the blood pipe narrow?

For further investigation we can take these two factors
Narrowing of pipe at specific position using clothespin
obstruction in the pipe

How would narrowing of the diameter of blood pipes affect blood flow? Write down your ideas.

How would obstruction in the blood pipe affect blood flow? Write down your ideas.

Can you think of way to check the effect of obstruction in the pipe?
You can introduce an obstruction in your experimental pipe using chewing gum or dough.
 

Is your guess matching with the result of our activity? What does it say about the effect of obstruction in pipe on the flow of blood?

In this activity we have seen that blood flow is affected by the diameter of the pipes. This in turn affects our blood pressure.
Depending on various factors like the above, blood pressure can be low or high. Both low blood pressure and high blood pressure are not good for our health.