Question

The veins from the stomach and intestine do not carry the blood directly to the inferior vena cava, instead they first enter the liver as a continued
A. Renal portal vein
B. Hepatic portal vein
C. Both A and B
D. None of these.

Answer 1

Hint:- Liver filters all the blood flowing from the stomach and intestines before draining it into the circulation. For this purpose, there is a portal system having veins that carry blood from the stomach and intestine to the liver.

Complete answer:
Step 1: Let us first understand as to why the blood from gastrointestinal tract needs to drain to the liver first before entering into general circulation.
The food that we take may contain some toxic substances or higher than permissible concentration of some dietary components and thus, needs to be filtered. Liver processes nutrients in the blood and the blood entering the liver gets filtered in a system of smaller veins.
Step 2: Let u now have a look at the function of renal portal vein and hepatic portal vein-
Renal portal vein- It is a portal vein carrying blood from some of the posterior parts of the body to kidneys in vertebrates. It carries blood from the caudal vein of the tail to kidney via two renal portal veins.
Hepatic portal vein- Hepatic portal vein and its tributaries constitute the hepatic portal system which carries blood from intestine, stomach and spleen to the liver where blood gets filtered and processing of raw nutrients is done before the blood returns to heart for general circulation.

Step 3: From the above discussion, it is clear that the correct option is (B)- Hepatic portal vein.

Note:- Liver receives both oxygenated and deoxygenated blood. Portal triad of liver consists of three tubes- hepatic artery, hepatic portal vein, and bile ducts. While hepatic artery branches supply oxygenated blood to hepatocytes, hepatic portal vein branches carry blood with nutrients from the gastrointestinal tract and are mostly deoxygenated. The bile duct serves to carry bile products to larger ducts and gallbladder.