SCIENCE
ZOOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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a one precard and two post caval
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b 2 Precaval and 2 postcaval
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c 2 precard and 1 postcard
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d 1 precaval and 1 post caval
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Detailed explanation-1: -The sinus venosus receives venous blood via paired Cuverian ducts, hepatic veins, and anterior jugular veins. The sinoatrial ostium is guarded by a large valve, and the openings of the hepatic veins into the sinus venosus are guarded by muscular sphincters.
Detailed explanation-2: -The left and right common cardinal veins are relatively short segments that connect to the sinus venosus. On each side, anterior and posterior cardinal veins join to form the common cardinal vein, the anterior carrying the venous return from the upper body and the posterior from the lower body.
Detailed explanation-3: -The coronary sinus receives blood mainly from the small, middle, great, and oblique cardiac veins. It also receives blood from the left marginal vein and the left posterior ventricular vein.
Detailed explanation-4: -In the frog, Rana, venous blood is driven into the right atrium of the heart by contraction of the sinus venosus, and it flows into the left atrium from the lungs.