small intestine
Digestion's absorption site
The small intestine is the narrow, coiled tube connecting the stomach to the large intestine, where most digestion and nutrient absorption occurs.
Despite its name, it's the longer of the two intestines—about twenty feet in adults—but narrower in diameter than the large intestine.
It comprises three sections: duodenum, jejunum, and ileum.
Initial small intestine
- jejunumSecond small intestine portion
- ileumLast small intestine segment
- villiIntestinal absorptive protrusions
- microvilliMicroscopic membrane protrusions
mucosa · mesentery · crypts of Lieberkühn · submucosa · serosa · muscularis
Reaction-speeding proteins
- chymePartially digested stomach contents
- peristalsisInvoluntary digestive muscle waves
- bileLiver-made digestive fluid
- pancreatic juiceDigestive enzymes from organ behind stomach
amylase · lipase · protease · carbohydrates · proteins · fats · segmentation · maltase
Vital dietary substances
- amino acidsOrganic compounds forming proteins
- glucosePrimary cellular fuel
- fatty acidsOrganic molecules in fats
- electrolytesConducting ions in solution
vitamins · minerals · permeability · osmosis · endocytosis · monosaccharides · peptides · water absorption
Autoimmune intestinal gluten reaction
- Crohn's diseaseChronic intestinal inflammation disorder
- gastroenterologistDigestive organ physician
- malabsorptionFailed intestinal nutrient uptake
- enteritisSmall intestine inflammation
Live microorganisms aiding digestion
- prebioticsFood for gut flora
- beneficial bacteriaHealth-promoting microorganisms
- fermentationMicrobial sugar conversion
- gut healthIntestinal microbiome condition
duodenum
Initial small intestine
- jejunumSecond small intestine portion
- ileumLast small intestine segment
- villiIntestinal absorptive protrusions
microvilli · mucosa · mesentery · crypts of Lieberkühn · submucosa · serosa · muscularis
enzymes
Reaction-speeding proteins
- chymePartially digested stomach contents
- peristalsisInvoluntary digestive muscle waves
- bileLiver-made digestive fluid
pancreatic juice · amylase · lipase · protease · carbohydrates · proteins · fats · segmentation · maltase · lactase
nutrients
Vital dietary substances
- amino acidsOrganic compounds forming proteins
- glucosePrimary cellular fuel
- fatty acidsOrganic molecules in fats
electrolytes · vitamins · minerals · permeability · osmosis · endocytosis · monosaccharides · peptides · water absorption · bile salts
celiac disease
Autoimmune intestinal gluten reaction
- Crohn's diseaseChronic intestinal inflammation disorder
- gastroenterologistDigestive organ physician
- malabsorptionFailed intestinal nutrient uptake
enteritis · ileus · adhesions · lactose intolerance · stricture
probiotics
Live microorganisms aiding digestion
- prebioticsFood for gut flora
- beneficial bacteriaHealth-promoting microorganisms
- fermentationMicrobial sugar conversion
- celiac diseaseceliac, celiac disease, gluten, gluten intolerance, gluten sensitivity
- gut absorptionvilli, microvilli, duodenum, jejunum, ileum
- digestionstomach acid, swallowing, digesting, chewing, digestion
- gutcolon, bowel, guts, entrails, innards
- body passagesmouth, nose, ear, nostril, anus
- innardsviscera, entrails, innards, insides, guts
small intestinelarge intestine
Lower digestive tract portion
colon · large bowel · rectum · cecum · ascending colon
small, smaller, smallest, intestines, intestine, intestinal, enteric, gastrointestinal, intestinal flora