Chapter 29, Problem 14A

Summary Introduction

To write:

About the circulation of reptiles and amphibians

Introduction:

Animal belongs to subphylum Vertebrata are called vertebrates. Vertebrates have a vertebral column and specialized cells that develop from the nerve cord. The vertebral column, also called a spinal column, is the hallmark feature of vertebrates. Classes of vertebrates include fishes, reptiles, amphibians, mammals, and birds. Vertebrates have a closed circulatory system in which the heart pumps blood through vessels.

Explanation of Solution

In most reptiles, oxygen from the lungs enters into a circulatory system that is similar to that of amphibians. Most reptiles have two separate atria and one ventricle that are partially divided by an incomplete septum. In crocodiles, however, the septum in the ventricles is complete, thereby resulting in a four-chambered heart. The separation into two ventricles keeps oxygen-rich blood separate from the oxygen-poor blood throughout the heart. Because reptiles generally are larger than amphibians, they need to pump blood forcefully enough to reach parts of the body far away from the heart.

The circulatory system of amphibian is consists of a double loop instead of the single loop. The first loop moves oxygen-poor blood from the heart to pick up oxygen in the lungs and skin, and then moves the oxygen-filled blood back to the heart. During circulation in the second loop, blood filed with oxygen moves from the heart through vessels to the body, where the oxygen diffuses into cells.

Conclusion

Reptiles have a double loop circulatory system with a loop that carries blood from and to the lungs and another loop that brings blood from and to the rest of the body. Amphibians have circulatory system with a single loop.