Q.
Which one of the following animals has two separate circulatory pathways?
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AIPMTAIPMT 2015Body Fluids and Circulation
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Solution:
Whale is a mammal and in mammals, two separate circulatory pathways are found systemic circulation and pulmonary circulation. Oxygenated and deoxygenated bloods received by the left and right atria I respectively pass on to the left and right ventricles. Thus, oxygenated and deoxygenated bloods are not mixed. This is referred to as double circulation. In shark (fish), the heart pumps out deoxygenated blood which is oxygenated by the gills and sent to the body j parts from where deoxygenated blood is carried to the heart. It is called single circulation. In frog (amphibian)and lizard (reptile), the left atrium get oxygenated blood from the gills/ lungs/skin/ buccopharyngeal cavity and the right atrium receives the deoxygenated blood from other body parts. The oxygenated and deoxygenated bloods get mixed up in single ventricle which pumps out mixed blood. This is called incomplete double circulation.