large intestine - rectum - blood supply Flashcards
(16 cards)
What artery supplies the upper rectum?
The superior rectal artery, which comes from the inferior mesenteric artery, supplies the upper rectum.
What artery supplies the middle rectum?
The middle rectal artery, which comes from the internal iliac artery, supplies the middle rectum.
What artery supplies the lower rectum and anal canal?
The inferior rectal artery, which comes from the internal pudendal artery, supplies the lower rectum and anal canal.
What is the venous drainage for the upper rectum?
The superior rectal vein drains the upper rectum and empties into the portal venous system.
What is the venous drainage for the middle and lower rectum?
The middle and inferior rectal veins drain the middle and lower rectum and empty into the systemic venous system.
What is the significance of dual venous drainage in the rectum?
The rectum has dual venous drainage:
Superior rectal vein drains into the portal venous system.
Middle and inferior rectal veins drain into the systemic venous system.
This explains why rectal varices can develop in portal hypertension, as blood flow is redirected from the portal system to the systemic system.
What artery supplies the rectum’s blood flow?
The rectum receives blood supply from three main arteries:
Superior rectal artery (from the inferior mesenteric artery) for the upper rectum.
Middle rectal artery (from the internal iliac artery) for the middle rectum.
Inferior rectal artery (from the internal pudendal artery) for the lower rectum and anal canal.
What is the clinical significance of rectal varices?
Rectal varices can develop due to portal hypertension. The dual venous drainage of the rectum (from both the portal venous system and systemic venous system) can cause blood to be redirected from the portal circulation to the systemic circulation, leading to varicose veins in the rectum.
What is the role of the superior rectal artery in blood supply to the rectum?
The superior rectal artery, which branches from the inferior mesenteric artery, provides blood to the upper rectum. It is the main source of blood flow to this part of the rectum.
How does the middle rectal artery contribute to the blood supply of the rectum?
The middle rectal artery, branching from the internal iliac artery, supplies the middle part of the rectum. It provides additional blood supply to the rectal area that is not covered by the superior or inferior rectal arteries.
What is the function of the inferior rectal artery in blood supply?
The inferior rectal artery, which originates from the internal pudendal artery, supplies the lower part of the rectum and the anal canal. It is critical for the blood flow to the anal region.
What happens to the blood flow in the rectum during portal hypertension?
In portal hypertension, the superior rectal vein (which drains into the portal venous system) may be blocked, causing blood to flow into the middle and inferior rectal veins. These veins drain into the systemic venous system, leading to the formation of rectal varices (swollen veins in the rectum).
What veins drain the upper rectum and how are they connected to the liver?
The superior rectal vein drains the upper rectum and carries the blood into the portal venous system, which leads to the liver. This connects the rectum’s venous drainage to the liver’s blood circulation.
How does the middle and inferior rectal veins differ from the superior rectal vein?
The middle and inferior rectal veins drain the middle and lower rectum, and they empty into the systemic venous system, which carries blood back to the heart.
The superior rectal vein drains the upper rectum and connects to the portal venous system, which goes through the liver.
Why is the dual venous drainage important for the rectum?
The rectum has dual venous drainage:
Superior rectal vein drains into the portal venous system (toward the liver).
Middle and inferior rectal veins drain into the systemic venous system (toward the heart).
This dual system is important because it helps maintain blood flow even if one system is blocked, but it also explains why rectal varices can develop in cases of portal hypertension.
How does the blood supply of the rectum relate to the development of hemorrhoids?
Hemorrhoids occur when there is increased pressure in the veins of the rectum and anal canal. The middle and inferior rectal veins are particularly affected in this condition. In portal hypertension, the increase in pressure in the superior rectal vein can also contribute to varices, which may result in hemorrhoids.
