Answer:
Carbohydrates are absorbed as monosachharides , lipids are absorbed as free fatty acid chains and monoglycerides, and proteins are absorbed as amino acids.
Small intestine is the main site of absorption in human beings. The macro-molecules are digested or breakdown into their simpler constituents before absorption.
Complex carbohydrates are digested with the help of enzymes salivary amylase (mouth), pancreatic amylase, and intestinal enzymes (like maltase, sucrase, lactase et cetera) into their respective monosachharides (such as glucose, fructose). These are then absorbed with the help of micro-villi.
Proteins are first digested into smaller peptides in the stomach with the help of pepsin. These peptides are then digested to dipeptides in the small intestine with the help of pancreatic enzymes like trypsin, chymotrypsin, and carboxypeptidase. These dipeptides are then digested to their respective amino acids with the help of intestinal juices. The amino acids are then absorbed with the help of micro-villi of small intestine.
In small intestine, fats are first emulsified into the small micelles with the help of bile. Pancreatic lipase then convert fats into diglycerides and monoglycerides. Finally, intestinal juices convert diglycerides into free fatty acids and monoglycerides.
