How Many Heart Chambers Do Frogs Have?

February 14, 2024

Frogs have a three chambered heart which consists of two atria and one ventricle. The ventricle is subdivided by muscular folds that prevent free mixing of oxygenated and deoxygenated blood. The heart of a frog is myogenic, meaning that contraction originates within the muscle itself. A wave of excitation spreads from the sinoauricular node to the septum between the atria and then down through and around them, driving heart contractions.

Amphibians are a group of cold-blooded vertebrates that include frogs, toads, salamanders and caecilians. They use their thin skin to breathe and absorb water. They are the only vertebrates that can survive without a lung.

The heart of a fish has two chambers – an atria and a ventricle. In the atria, deoxygenated blood enters and in the ventricle, it gets mixed with oxygenated blood before being pumped out of the heart. This method of circulation is inefficient compared to that of mammals as it does not supply sufficient amount of oxygen to the body.

During evolution, the cardiovascular system of vertebrates adapted to support different modes of gas exchange. This led to a wide range of cardiac structures that are adapted to various metabolic rates and gas-exchange systems. For example, the atrioventricular valve is present in lungfishes but absent in amphibians and reptiles. In addition, the ventricular septum is missing in the hearts of reptiles and birds but present in mammals and humans.

In order to maintain a higher metabolic rate, the cardiovascular system needs to be able to provide the body with enough oxygen. This can only be achieved by separating oxygenated and deoxygenated blood. To this end, the four-chambered heart was developed in mammals and birds to accommodate the increase in oxygen requirements caused by air-breathing.


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