Vessels which bring back blood to heart from different parts of body are called veins.
Veins join to form venous system. This system consists of following veins: -
Pulmonary Veins: -
These bring blood from lungs. They carry oxygenated blood.
Right & Left Precavals: -
Each precaval is formed by three veins. These bring blood from lower jaw, head,
shoulders, skin and forelimbs.
Post Caval: -
It is formed by six pairs of renal veins. It brings blood from kidneys.
Renal Portal Vein: -
Veins which bring blood from hind limbs and pelvic region join to form renal portal
vein. This enters into kidney and joins post caval.
Abdominal Vein: -
Pelvic veins join to form abdominal vein. This vein enter into liver and divides into
capillaries. Then this blood enters into post caval.
Hepatic Portal Vein: -
Veins which bring blood from digestive system are called hepatic portal vein. This
blood is also reached to liver and finally enters into post caval.