Chapter 49, Problem 1Q

Summary Introduction

To review:

The change in blood flow after the surgical removal of the pulmonary bypass shunt in alligators, with the help of a diagram, and how the surgery made the alligator heart behave like a bird heart.

Introduction:

The heart in crocodiles and alligators has four chambers, but they differ from bird hearts because they have two aortas. The two aortas are connected by a shunt known as the pulmonary bypass shunt. A surgery was performed in order to remove this shunt by closing the left aorta near the left ventricle.

Explanation of Solution

The surgery was performed and the flow of blood after the surgical removal of the pulmonary bypass shunt in alligator heart is shown in the figure below:

The diagram shows the potential flow of blood through the alligator’s heart at the time of the cardiac shunt. The blood flows from the left aorta, foramen of Panizza, and into the right aortic arch. The scissors symbol and the dotted lines in the diagram show the location at which the surgery was performed and the flow of blood to the left aorta was blocked.

After the surgical removal of the cardiac shunt, the alligator heart became similar to a bird heart. The major difference between the bird and alligator heart is that the alligator heart has two aortas, while the heart in birds has only one. The occlusion of the left aorta in alligator meant that it was only left with one functional aorta through which the blood could flow.

The right ventricle would pump blood into the lungs through the pulmonary artery and the left ventricle would pump blood to the rest of the body through the aorta.

Conclusion

Therefore, it can be concluded that by blocking the left aorta or by removing the pulmonary bypass shunt surgically, the alligator heart starts behaving like a bird’s heart.