Portal Circulation Flashcards
Size of the portal vein
8 x 1 cm
What regions of the body are drained by the portal circulation?
Abdominal part of the Alimentary Tract (except lower part of the Anal Canal)
Spleen and Pancreas
What is the purpose of the portal circulation?
Conveys absorbed products of digested food to the liver
Does the portal circulation have valves?
No
How much blood flows through the portal circulation each minute?
1200 ml/min
What two veins primarily form the portal vein?
Superior mesenteric vein
Splenic vein
Where does the portal vein form?
Behind the neck of the Pancreas and IVC at the transpyloric plane
At the level of L2
What are the two segments of the portal circulation?
Extrahepatic part
Intrahepatic part
Describe the course of the extrahepatic part of the portal circulation
Passes upwards and right, behind neck of the Pancreas and 1st part of Duodenum
Enters right free margin of the lesser omentum in front of the epiploic foramen with the Bile Duct and Hepatic Artery
Reaches the Porta Hepatis and divides into right and left branches
Describe the course of the intrahepatic part of the portal circulation
The portal vein enters the liver and breaks up into sinusoids
Blood passes into the hepatic veins that join the inferior vena cava
Tributaries of the portal vein
Splenic vein
Superior mesenteric vein
Left gastric vein
Right gastric vein
Cystic veins
Course of the splenic vein
Leaves the hilum of the spleen and passes to the right in the splenorenal ligament
Unites with the superior mesenteric vein behind the neck of the pancreas to form the portal vein
Which veins does the splenic vein receive?
Short gastric, left gastroepiploic, inferior mesenteric, and pancreatic veins
Course of the superior mesenteric vein
Ascends in the root of the mesentery of the small intestine
Passes in front of the third part of the duodenum and joins the splenic vein behind the neck of the pancreas
Which veins does the superior mesenteric vein receive?
Jejunal, ileal, ileocolic, right colic, middle colic, inferior pancreaticoduodenal, and right gastroepiploic veins
Function of the left gastric vein
Drains the left portion of the lesser curvature of the stomach and the distal part of the esophagus
Opens directly into the portal vein
Function of the right gastric vein
Drains the right portion of the lesser curvature of the stomach
Drains directly into the portal vein
Function of the cystic vein
Drain the gallbladder directly into the liver or join the portal vein
What are the branches of the portal vein?
Right Branch
Shorter, wider
Receives cystic vein
Left Branch
Narrower, longer
Runs in the porta hepatis from Right to Left
Branches to Caudate and Quadrate Lobe
Recieves the paraumbilical veins
What are the parts of the portal circulation?
Infraduodenal
Retroduodenal
Supraduodenal
What are the relations of the infraduodenal part of the portal vein?
Anterior: Neck of the pancreas
Posterior: Inferior Vena Cava
What are the relations of the retroduodenal part of the portal vein?
Anterior:
Duodenum (1st part)
Bile Duct
Gastroduodenal Artery
Posterior:
Inferior Vena Cava
What are the relations of the supraduodenal part of the portal vein?
Anterior:
Hepatic Artery
Bile Duct
Posterior:
Inferior Vena Cava
What is a portocaval anastomosis?
The hepatic veins normally drain the portal circulation into the IVC
Smaller communications exist between the portal and systemic systems, and they become important when the direct route becomes blocked
What are the sites of portocaval anastomosis?
Abdominal part of the esophagus
Umbilicus
Anal canal
Bare area of the liver
What are the causes of the portal hypertension?
Liver Cirrhosis
Blood cots in the portal vein
What is the condition for portal hypertension?
Pressure above 40 mmHg
What are the consequences of portal hypertension?
Caput Medusae
Oesophageal varices
Hemorrhoids
Ascites
Splenomegaly
