Chapter 29, Problem 16STP

Summary Introduction

To write:

The difference between the circulatory system of a frog with the circulatory system of a fish and assess the importance of those differences.

Introduction:

Amphibians include toads, frogs, salamanders, newts, and legless caecilians. Most amphibians are distinguished by moist skin without scales, four legs, exchange of gases through skin, a circulatory system with double loop, lungs, and aquatic larvae. Fishes live in aquatic habitats like lakes, seas, rivers, ponds, etc. Some fishes live in complete darkness at the bottom of the deep ocean whereas others live in the freezing water of the Polar Regions and have special proteins in their blood to keep the blood from freezing. There are about 24,600 species of living fishes are found.

Explanation of Solution

Most adult amphibians breathe through their lungs. The amphibian circulatory system is closed. It consists of a double loop. The first loop takes oxygen-less blood from the heart to pick up oxygen from the lungs and skin, and then transfers the oxygen-filled blood back to the heart. During circulation in the second loop, the oxygen-filled blood travels from the heart to the body through the vessels, where oxygen spreads to the cells. Amphibians have three chambered heart. The atrium is completely separated into two atria by tissue. The deoxygenated blood from the body receives the right atrium, while the left atrium receives oxygen-filled blood from the lungs. The ventricle remains undivided.

In most fish, blood passes through the heart in a one-way loop. The blood flows from the heart to the gills, and then through the body, delivering oxygen-filled blood to the tissues. Then the blood goes back to the heart. Blood pumped back to the gills from the heart, and then back to the body. Because this system is a complete and uninterrupted circuit, it is known as a single-loop circulatory system. The heart of the fish comprises of two main chambers, the atrium and the ventricle. The atrium is the chamber of the heart which receives blood from the body. Blood is transferred from there to the ventricle. Ventricle is the chamber of the heart, which pumps blood from the heart to the gills. When the blood passes through the gills, it moves to the rest of the body.

Conclusion

Thus, the circulatory system of fishes and amphibians can be differentiated on the basis of the heart chambers and the loops.