Anatomy of finfish and shellfish

Unit 5 - Circulatory System

5.2.5. Venous system
The blood distributed to the different parts of the body by the arteries and their braches through capillaries and returned to the heart by the veins. The veins differ in structure from the arteries in possessing thin walls and in forming wide irregular spaces called sinuses (during then curve)
The Venus system can be devided into the following systems.

• Anterior cardinal system.
• Posterior cardinal system
• Hepatic portal system
• Ventral sinus
• Cutaneous system.

Anterior cardinal system: the anterior cardinal system consists of the following viens, the internal juglar veins it has the alfactory sinus, orbital sinus, post orbital sinus and anterior cardinal sinus. The orbital sinus finally opens into large anterior cardinal sinus. It opens into ductus cuaveri.
The posterior cardinal system: This system consists of medium caudal vein two renal veins and two large posterior cardinal sinuses. The renal portal vein gives of branches to kidney recollect into renal veins to form the posterior cardinal sinuses.
Hepatic portal system: This system has the hepatic portal vein anterior and posterior intestinal veins, gastric vein and the anterior and posterior gastric. These subsequently form hepatic sinuses which open into sinus venosus.
Ventral veins: The ventral vein comprises two groups. 1) the anterior veins which discharges the blood into ductus curvier through the inferior jugular sinuses and the posterior veins which empty their blood through the subclavians.
Cutaneous systems: The cutaneous system includes a dorsal, a ventral and two paired lateral veins. The ventral joins the abdominal veins. The laterals empties into the branchial vein.