Page 35 - 11-Bio-14 Transport

14. Transport eLearn.Punjab

Fig.14.18 A schematic comparison of vertebrate heart and circulation of blood. (A) In modern fish
the blood is pumped to the gills, where it picks up oxygen. The oxygenated blood (red) then passes
without further pumping to the systemic circulation, where it gives up its oxygen before returning
to the heart. (B) In amphibians the blood that has picked up oxygen in the gills and/or lungs returns
to the heart, from which it is pumped into the systemic circulation. Extensive mixing (purple) of
the pulmonary and systemic flows occurs in the heart. (C) In reptiles the pattern is much the same,
except that the ventricles are partially divided, so less mixing takes place. (D) In mammals and birds
the two halves of the heart are effectively separated.

The heart of reptiles and all other amniotes practically functions as four chambered heart. There
are two auricles in the heart of reptiles. The reptiles have incompletely partitioned ventricle; but in
crocodiles, the interventricular septum is complete and heart is four chambered. In all reptiles the
left and right systemic arches carry oxygenated blood and arise from a region of ventricle called

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