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Monday, April 22, 2013

HSEB Notes on Venous System of Circulatory System of Human Beings Class 12

Biology | Zoology
HSEB Notes on Venous system | Circulation
Class : 12

All veins in the body together make venous system. This system is for collection of pure blood from lungs and impure blood from rest of the parts of body. Four pulmonary veins collect pure blood form lungs and open into left atrium. Superior venacava collect blood from anterior part of body. It is made by different veins. Right and left innominate veins join to form superior venacava. Each innominate is made by right and left external and internal jugular veins collecting blood from head and brain. The right and left subclavians collect from hand. The subclavian is again made by axillary and cephalic veings. Azygous vein collects from chest region in the right side. Hemiazygous collect from left side . both open into superior venacava. Inferior venacava is made by different veins. Two short and thick hepatic veins collect blood from liver. 

Two common iliac veins join to make the inferior venacava. Each iliac vein is made by internal iliac from urinary bladder, large saphenous from thigh, anterior and posterior tibial from lower part of leg.

The blood collection form stomach and intestine has different arrangement. It is called Portal system. The blood is not directly carried to the heart. It is taken to liver first. Gastric vein, duodenal vein, intestinal veins etc join to form hepatic portal vein. It enters into liver to form hepatic portal system. 

Importance of hepatic portal system
  • Stores excess glucose in the form of glycogen
  • Converts highly poisonous ammonia into less poisonous urea
  • Kills Bacteria, germs etc and protect from diseases
  • Removes impurities
  • Regulate body temperature etc.
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