Why amphibians and reptiles have complete and incomplete blood Circulatory ststem while in chordates one time and two time blood touch to the heart???
Answers
Amphibians have a three-chambered heart - two atria and one ventricle. The mixing of oxygenated and deoxygenated blood is kept to a minimum due to the timing of the contractions between the atria. This is called an incomplete double circulatory system.
Three chambered amphibian heart with two atrium and one ventricle.
Amphibian lungs are balloon-like structures where gas exchange is limited. As a result, oxygen can be diffused through their moist skin (and sometimes their mouths) to compensate.
Amphibians force the air into their lungs using throat muscles in a process called buccal pumping.
Frog respiratory system.
Reptiles
Reptiles have a three-chambered heart – two atria and one partially divided ventricle. There is a mixing of oxygenated and deoxygenated blood because the ventricle is not split completely.
Reptile heart with two atria and one partially divided ventricle.
The only exception to this physiological structure in reptiles is the crocodile. The crocodile has a four-chambered heart similar to mammals and birds where the ventricles are split completely.
Fish
Fish have the simplest vertebrate heart with only two chambers - one atrium and one ventricle. This is called a single cirulatory system.
Fish heart with one atrium and one ventricle.