B. Valves in the Veins The physician Galen in ancient Greece postulated that blo
ID: 3509278 • Letter: B
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B. Valves in the Veins The physician Galen in ancient Greece postulated that blood ebbs and flows back and forth in the blood vessels. The following experiment that blood moves in a circular path through the body, not back and forth. performed by William Harvey demonstrated Pair u p with another person in the lab. One person will volunteer to be the subject and the other will conduct the experiment. Write down your observations and results below Often men are better subjects because their veins in their arms are larger and easier to 1. Tie a tourniquet (not so tight that it is uncomfortable) around the arm above the elbow of the subject. This will prevent venous return of blood to the heart. Note the enlargements of the veins and the localized swellings that mark the position of the valves 2. Press one finger firmly down on a distal part of a vein preventing blood flow back up the arm toward the tourniquet. Use another finger and massage the blood out of the vein toward the tourniquet. This will push blood past a valve that is more proximal 3. Remove the second finger and note the blood flow back into the vein Does the blood travel back to where the first, distal positioned finger is being held down? Explain your observation. Now press the blood from above the valve (tourniquet side) distally, toward the valve. What happens? 4. Why? 5. Now have the subject open and close his/her fist for one minute. This will exercise the muscles in the arm. Now repeat the steps above. How do the filling times of the vein during rest and after exercise compare? Explain your results.Explanation / Answer
1. The upper limbs plays the vital role of ensuring the adequate flow of blood to and from shoulders, arms, hands, and fingers. Oxygenated blood exists the heart through the aorta and reaches the arms through the brachiocephalic trunk.
2. If we press the finger firmly down on the digital part of the vein, blood flow is increasing to the down part and preventing the upper part of the body.
3. Yes, the blood travel back to where the first, distal positioned finger is being hold down.
4. After the pressing of blood flow above the value distally, the blood flow towards the lower part of the value. Because your pulse rate is vary in one minute.
5. Your pulse is lower when we were in rest and increases when you exercise (more oxygen rich) blood is needed by the body when we were in exercise.
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