Question
Discuss the basic structures of the heart in different groups of vertebrate animals as evidence of organic evolution.
Or,
Substantiate evolution with the help of morphological evidence.
Answer
The basic structure of the heart varies among different groups of vertebrate animals, providing evidence of organic evolution:
- Fish: The heart of fish is a simple, two-chambered structure consisting of an atrium and a ventricle. The atrium receives deoxygenated blood from the body, while the ventricle pumps it to the gills for oxygenation.
- Amphibians: The heart of amphibians is a three-chambered structure consisting of two atria and a single ventricle. The right atrium receives deoxygenated blood from the body, while the left atrium receives oxygenated blood from the lungs. The ventricle pumps a mixture of oxygenated and deoxygenated blood to the body and lungs.
- Reptiles: The heart of reptiles is also a three-chambered structure, but with a partially divided ventricle that separates oxygenated and deoxygenated blood to some extent. This improves oxygenation and allows reptiles to survive in diverse environments.
- Birds and mammals: The heart of birds and mammals is a four-chambered structure consisting of two atria and two ventricles. The right atrium receives deoxygenated blood from the body, while the left atrium receives oxygenated blood from the lungs. The right ventricle pumps deoxygenated blood to the lungs, while the left ventricle pumps oxygenated blood to the body. This separation of oxygenated and deoxygenated blood allows for greater efficiency in oxygen delivery to tissues.
