Page 36 - 11-Bio-14 Transport

14. Transport eLearn.Punjab

cavum venosum - into which left ventricle directs its blood. The deoxygenated blood from the right
atrium is directed towards the entrance of the pulmonary trunk which is also located or starts from
a pocket the cavum pulmonale, on right side of ventricle- in the animals (reptiles) which do not have
completely divided ventricle. Although the two systemic arches start from the ventricle separately,
they are also interconnected at their base by an opening. The heart of reptiles birds and mammals
functions as double circuit heart. (Fig. 14.19c).
In the birds and mammals, the heart is four -
chambered, and oxygenated and deoxygenated
blood does not mix at all. The pulmonary trunk
arises from right ventricle and leads to the lungs.

The aortic trunk emerges from the left ventricle
and leads to carotid and systemic arches. The left
systemic disappears in birds and right systemic,
most of it, disappears in mammals. (Fig. 14.19
D).

In reptile, birds and mammals, as a result of
these modifications, all blood returning to the
right side of the heart passes to the lungs. After
oxygenation, blood returns to left atrium from
the lungs via pulmonary veins. Left atrium passes
this blood to left ventricle - which on contraction
pumps it to different parts of the body, and
again blood returns to right atrium (Fig.14.18D).
Pulmonary circulation is by pulmonary arch
carrying deoxygenated blood from right ventricle
of heart to lungs, and the blood returns to left
atrium after oxygenation via pulmonary veins.

Likewise the systemic arch distributes blood Fig. 14.19 The human circulatory system
to different parts of the body, and then the
blood from the body returns to the heart, in V: 1.1
the right atrium via precaval and postcaval.
This is systemic circulation. So the hearts of
amphibians, reptiles, birds and mammals have
both pulmonary and systemic circulation.

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