Final answer:
Substances must cross the epithelial layer of the villi in the small intestine to enter the blood or lymphatic capillaries during absorption. Water-soluble nutrients enter the capillary blood in the villi and travel to the liver via the hepatic portal vein. Lymph in the lacteals absorbs fatty acids and fat-soluble vitamins.
Step-by-step explanation:
Substances must cross the epithelial layer of the villi in the small intestine to enter the blood or lymphatic capillaries during absorption. The thin surface layer of epithelial cells of the villi transports nutrients from the lumen of the small intestine into these capillaries and lacteals.
Water-soluble nutrients enter the capillary blood in the villi and travel to the liver via the hepatic portal vein. Lymph in the lacteals absorbs fatty acids and fat-soluble vitamins.