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Conclusion 4.1.1.
1. Which chamber of the heart do you think is the most muscular? Explain your
reasoning.
It's the left ventricle because it needs to pump the blood through the whole body.
2. A growing fetus has a vessel, the ductus arteriosus, in the heart that connects
the pulmonary artery with the aorta and conducts blood directly from the right
ventricle to the aorta. Why do you think this vessel closes soon after birth?
It closes because it can strain the heart and increase blood pressure in the lung
arteries.
3. In most of the body, the arteries carry oxygenated blood and the veins carry
deoxygenated blood. The exception to this pattern is the heart. Explain how and
why specific arteries and veins of the heart are different from the pattern seen in
the rest of the body.
Veins are thin-walled and don't need to cope with much pressure as the arteries
that are thick and muscular-walled, which are flexible to cope with the differing force of
blood flow by heart contraction. The rest of the veins and arteries in the body just carry
the blood to the whole body and not making as much pressure as the veins and arteries
of the heart.
4. Describe the mechanisms in place to prevent the blood from flowing in the wrong
direction through the heart.
The AtrioVentricular Valves prevent the back flow of the blood to the atria when the
ventricles contract.
And..
The Semilunar Valves prevent the back flow of the blood from the arteries to the
ventricles
5. Explain what happens to tissues, such as the heart, or the brain, if oxygenated
blood is not delivered in a timely manner.
The tissue of the organ starts to die.
Project Lead The Way, Inc.
Copyright 2012
PBS – Activity 4.1.1: Path of Blood in the Heart – Page 1