anatomy of the heptaic portal system and portosystemic anastomoses

portal system

- transport of substance between 2 organs

- venous blood flow through the portal vein

- venous blood flow between capillary beds before returning to the heart

systemic circulation

1. heart

2. artery

3. capillary bed

4. vein

5. back to heart

portal circulation

1. heart

2. artery

3. capillary bed

4. portal vein

5. capillary bed

6. systemic veins

7. back to heart

venous flow through the liver overview

- hepatic portal vein

- liver capillary bed

- sublobular hepatic vein

- hepativ vein

venous flow through the liver

1. heart

2. digestive arteries

3. digestive capillary bed

4. hepatic portale vein

5. liver capillary bed

6. inferior vena cava

7. back to heart

organs the hepatic portal vein drains into

- stomach (lesser curvature)

- esophagus

- gallbladder

organs the splenic vein drains into

- stomach (left greater curvature)

- hindgut organs (indirectly)

- pancreas (neck, body, tail)

- spleen

organs the superior mesenteric vein drains into

- stomach (right great curvature)

- pancreas (head)

- duodenum

- midgut organs

organs the inferior mesenteric drains into

- hingut organs (directly)v

key point summary about the hepatic portal system

- venous system of the digestive system

- the main veins are the hepatic portal, splenic, superior mesenteric, and inferior mesenteric veins

- the hepatic portal vein collects the nutrient rich venous blood and delivers it to the liver

- hepatic portal vein directly collects blood from the stomach (lesser curvature), gallbladder, and distal esophagus

- splenic vein collects blood from the pancreas, stomach, spleen, and (indirectly) hindgut organs

- superior mesenteric vein collects blood from the midgut organs, stomach, pancreas, and duodenum

portal hypertension

- increase blood pressure w/n the veins of the digestive organs

- due to blockage in blood flow to the liver

- leads to varices in the digestive organ veins

- causes: liver cirrhosis, thrombosis

protosystemic anastomosis

- portal venous system communicates with the systemic system

- alternate route for blood to trravel to the inferior vena cava or superior vena cava

- clinical problems: esophageal varices, hemorrhoids, caput medusa

locations of portosystemic anastomoses

1. gastroesophageal junction

2. anal canal

3. umbilicus

veins involved/connected to porotsystemic anastomoses

- azygous veins

- esophageal vein

- inferior epigastric vein

- inferior mesenteric vein

- inferior vena cava

- internal iliac vein

- left and right gastric vein

- middle and inferior rectal vein

- paraumbilical vein

- periumbilical vein

- superior epigastric vein

- superior mesenteric vein

- superior rectal vein

- superior vena cava

portosystemic anastomosis~ gastroesophageal junction

- portal vein->

- left and right gastric vein->

- esophageal vein->

- azygous vein->

- superior vena cava ->

- heart

esophageal varices

- engorgement that pops out due to blockage

portosystemic anastomosis~ anal canal

- portal vein->

- inferior mesenteric vein ->

- superior rectus vein ->

- internal rectal plexus->

- middle/inferior rectal vein->

- internal iliac vein->

- inferior vena cava

internal hemorrhoids

- occurs in internal rectal plexus

- due to blockage

portosystemic anastomosis ~ umbilicus

- portal vein ->

- para-umbilical vein ->

- peri-umbilical vein (forms a portosystemic anastomosis in umbilicus->

- superior/inferior epigastric vein->

- superior/inferior vena cava->

- heart

capcut medusa

- due to a blockage at the umbilicus

portosystemic shunt

- shunt w/n liver to connect hepatic portal vein to veins that will connect blood to try to bring in regular venous blood flow through systemic circulation

- not a long term treatment

- typically done on liver transplant pts

key point summary about portosystemic anastomoses

- commections btwn the hepatic portal system and the systemic circulation

- distal esphageal veins forms a portosystemic anastomosis in the gastroesophageal junction and leads to esophageal varices

- internal rectal plexus forms a portosystemic anastomosis in the anal canal an leads to internal hemorrhoids

- periumbilical vein forms a portosystemic anastomosis around the umbilicus and leads to capcut medusa