Portal Venous System Flashcards
What are the two interlinked venous systems within the trunk?
- portal venous system
- caval (systemic) venous system
What does the portal venous system drain?
gastrointestinal tract, spleen, pancreas, and gallbladder
Where are the various nutrients picked up?
- all nutrients, except for fats, pass through the portal system to the liver
- fats are picked up by lymphatic vessels of the small intestine (called lacteals) and bypass the liver
What is the path of blood flow in the portal venous system?
- from the GI tract, spleen, pancreas, and gallbladder
- to tributaries of the portal vein
- then to the portal vein, which divides into left and right branches
- then to the liver sinusoids (detox, storage, etc.)
- then to the inferior vena cava (caval system) via the hepatic veins
What does the caval venous system drain?
everything, except the GI tract, spleen, pancreas, and gallbladder
What is the path of blood flow in the caval venous system?
- from the body wall and organs
- to tributaries of the superior and inferior vena cava
- then to the superior and inferior vena cava
Where is the portal vein?
formed behind the head of the pancreas by the union of the splenic vein and superior mesenteric veins
What are the tributaries of the portal vein and what do they drain?
- Splenic vein
- short gastric veins - drain fundus
- left gastro-omental vein - drains greater curvature
- pancreatic veins - drain pancreas, pick up hormones
- inferior mesenteric vein
+ left colic vein - drains descending colon
+ sigmoid veins - drain sigmoid colon
+ superior rectal vein - unites with sigmoid vein to form inferior mesenteric vein; drains rectum and upper part of anal canal - Superior mesenteric vein
- jejunal and ileal veins - drain jejunum and ileum
- ileocolic vein - drains ileocecal junction
- right colic vein - drains ascending colon
- middle colic vein - drains transverse colon
- right gastro-omental vein - drains greater curvature
- pancreaticoduodenal veins - drain head of pancreas - Left gastric vein - drains lesser curvature and distal esophagus
- Paraumbilical veins - accompany the ligamentum teres to the umbilicus
Where is colon cancer most like to to metastasize?
most common organ outside the intestine for metastasis of colon cancer is the liver due to the portal drainage
Which of the tributaries of the portal vein does not accompany an artery of the same name?
paraumbilical vein
What is cirrhosis of the liver?
- a condition characterized by destruction of hepatic cells and their replacement by fibrous tissue and fat
- the liver becomes nodular and hard, and tends to constrict the portal vein at the porta hepatis, causing portal hypertension
- causes:
1. alcoholism - most common
2. hepatitis
3. chronic obstruction of the bile duct
4. congestive heart failure
What is portal hypertension?
- abnormal elevation of pressure within the portal system, often due to cirrhosis of the liver; may also be due to liver cancer
- the portal vein is constricted within the porta hepatis
- the portal system has no valves - flow is reverse, bypassing the liver
- blood backs up into the caval system in the regions where portal-caval anastomoses occur
- the veins in these areas become varicose (dilated, tortuous, and thin-walled) and may rupture
At the distal esophagus, what is the caval vein, portal vein, obstructive sign, and note associated with the portal -caval anastomoses?
- caval vein: esophageal
- portal: left gastric
- obstructive sign: esophageal varices
- note: can hemorrhage with severe and often fatal bleeding
Around the umbilicus, what is the caval vein, portal vein, obstructive sign, and note associated with the portal -caval anastomoses?
- caval vein: superficial veins of anterior abdominal wall
- portal vein: paraumbilical
- obstructive sign: caput medusae
- note: pronounced snake-like veins radiating around the umbilicus; present only in severe cases
At the rectum and anal canal, what is the caval vein, portal vein, obstructive sign, and note associated with the portal -caval anastomoses?
- caval vein: middle and inferior rectal
- portal vein: superior rectal
- obstructive sign: hemorrhoids
- note: not diagnostic for portal hypertension when present alone
