Question

Out of the following, which substance is not related with hepatic portal circulation?

• A. L - amino acid
• B. Fatty acid
• C. Glucose
• D. Fructose

Answer 1

The correct option is B Fatty acid

Absorption of free fatty acids and monoglycerides takes place through the mucosal lining of the small intestine, and then they enter the epithelial cells. Once inside the cells, the free fatty acids and monoglycerides enter the endoplasmic reticulum, which is a system inside the cell whose functions include synthesis and transport of lipids. Here, the digested products are resynthesized into triglycerides. Triglycerides are the major form of fat stored by the body. This makes fat absorption different than absorption of proteins and carbohydrates. With protein and carbohydrate absorption, we see their basic units, which are amino acids and monosaccharides, are able to pass through the intestinal epithelial cells without being altered. Before triglycerides actually leave the epithelial cells, they're coated by proteins, which results in the formation of chylomicrons. The coating of protein gives the triglyceride a water-soluble coat, and this allows the chylomicron to travel outside of the cell. The newly formed chylomicrons leave the epithelial cell and enter the lymphatic capillaries, which are called lacteals. The lacteals are found in the fingerlike projections of the intestinal wall, called the villi. The lacteals represent another unique way fats are absorbed because lipids pass through the lymphatic system before they make their way back to bloodstream.
Fatty acids differs from protein and carbohydrate digestion because they unlike of amino acids and monosaccharides enter the lymphatic system; amino acids and monosaccharides instead travel directly into the blood capillaries and then into the hepatic portal vein that leads to the liver.
Dietary carbohydrates are digested to yield simple sugar molecules in the gut. Simple sugars like glucose, galactose and fructose pass from the intestinal lumen to the liver via the portal circulation. Glucose makes up about 80% of absorbed dietary sugars. Galactose and fructose make up the difference.
Regardless of whether amino acids enter the intestinal cells as peptides or amino acids, they enter the hepatic portal circulation as single amino acids. L-amino acids have higher affinity than the D-forms.