22.5 small intestine

small intestine

• responsible for 90% of digestion and is a major site of absorption and broken food down into simple monomers

• mix liver and pancreatic secretions with chyme (from stomach)

• absorb nutrients

• move chyme towards large intestine

• produce regulatory hormones

• produce immune cells in large numbers (protection with bacteria in food)

food types

• carbohydrates: carbohydrase

• proteins: protease

• lipids/fatty acids: lipase

• nucleic acids (DNA/RNA): nuclease

brush borders

• nutrient digestion and absorption occur

• helps inc. surface area and inc. absorption

plicae

the folds in the small intestine

villi

• within the plicae

• have lacteals

• help inc. surface area

microvilli

• have the brush borders

• columnar epithelium

  • inc. surface area even more by approx. 600 FOLD

lacteal

• part of capillary network within the villi

• supply blood and movement of H₂O to the villi

diarrhea

• food is too watery, SI isn’t able to absorb nutrients or water

• will leave you malnourished and dehydrated