Observation of blood flow in arteries and veins.
Procedure:
1. Sit on a table with one leg dangling and the other resting on it so that the back of one knee rests on the knee of the other.
2. After some time we feel the leg which is on top give a series of small movements with each heart beat.
3. Repeat it for a long time.
Observation: The blood flow reduces to the leg and so develop “pins and needles”. Conclusion: The blood flow from arteries to legs slowed down results pins and needles.
Swing the arm round several times to fill the veins with blood, hold the arm vertically downwards and gently press your finger along a prominent vein – stroking it in the reverse direction to the blood flow.
Observation: We can see the swellings.
Conclusion: Veins have to carry blood from body parts to the heart. When the arm is hold tightly blood is stopped in the veins there forms swelling.
