Final answer:
Carbohydrates are digested beginning in the mouth and continue in the small intestine; they are categorized as monosaccharides, disaccharides, and polysaccharides. Monosaccharides are absorbed the fastest since they require no digestion, while polysaccharides take the longest time to digest.
Step-by-step explanation:
Carbohydrates are digested in different parts of the digestive system, with digestion primarily beginning in the mouth, continuing in the small intestine, and ending in the same place where they are completely broken down and absorbed.
The three types of carbohydrates - monosaccharides, disaccharides, and polysaccharides - are digested at different speeds. Carbohydrate digestion starts with salivary amylase in the mouth breaking down polysaccharides like starch into smaller chains and some disaccharides. Digestion then continues in the small intestine with the help of pancreatic amylase, where these are further broken down into absorbable sugars.
In terms of digestion speed, the order from fastest to slowest is:
- Monosaccharides (like glucose and fructose) - requiring no digestion, they are rapidly absorbed.
- Disaccharides (such as sucrose and lactose) - need to be broken down into monosaccharides by enzymes like lactase and sucrase.
- Polysaccharides (including starch, glycogen) - take the longest time for digestion as they need to be broken down into mono- and disaccharides before being absorbed.
Fiber, a type of carbohydrate present in plant foods, is mostly undigested and passes through the digestive system, providing various health benefits.