Page 34 - 11-Bio-14 Transport

14. Transport eLearn.Punjab

Thus the heart of fishes works as a single circuit heart. The blood flows in one direction only,

from sinus venosus to atrium then to ventricle The heart of the fishes never receives oxygenated blood.
and to ventral aorta via bulbus arteriosus or conus It is only the deoxygenated blood which passes through
arteriosus to the gills and then to the body. The different chambers of the heart. (Fig. 14.18 a). The valves
blood returns to the heart in the sinus venosus The present in the heart control the flow of blood in single
oxygenated blood is supplied from dorsal aorta direction i.e. sinus venosus —> atrium —> ventricle conus
through coronary arteries,to the heart and is carried arteriosus —> ventral aorta —> gills —> dorsal aorta —»
body —» sinus venosus. So the heart of fishes functions as
a single circuit heart.

back by coronary veins from the heart).

In amphibians the heart is three chambered with regard to auricles and ventricles.There are two
auricles and one ventricle. In addition, sinus venosus and truncus arteriosus are also present.
Sinus venosus receives de-oxygenated blood from two superior venacavae (precavals) and one
inferior vena cava (postcaval) from different parts
of the body. This blood passes to the right auricle.
The oxygenated blood from lungs is poured via
pulmonary veins into left auricle. Both auricles
contract simultaneously and blood is passed
into the ventricle. There is a complete mixing
of oxygenated and deoxygenated blood in the
ventricle. When ventricle contracts, it pushes
blood via truncus arteriosus, to two carotids, two
systemics, and two pulmocutaneous arches.
(Fig. 14.19b).

Fig. 14.17 Structure of heart of frog

Animation 14.9: Structure of heart of frog
Source and Credit: multelearn

34 V: 1.1