GI 2 Flashcards
where is digestion initiated
in the mouth
- chewing
- saliva
- swallow
when is bolus referred to as chyme
once enters the stomach
explain the anatomy breakdown of intestine
first 1/3: duodenum
middle 1/3: jejunum
final 1/3: ileum
trace pathway of food bolus from mouth to small intestine
mouth–>esophagus–>stomach–>SI
how much fluid is absorbed compared to how much is excreted from the body and where is it mostly absorbed
massive amount of fluid is absorbed in the SI
much more than is excreted from the body (minimal amount is excreted in urine and feces)
layers of GI tissues from lumen to just lining abdominal cavity
- mucosa
- single layer of epithelial cells
- lamina propria
- muscularis mucosa - submucosa
- major blood vessels
- submucosal nerve plexus - muscularis externa
- circular muscle
- myenteric nerve plexus
- longitudinal muscle - serosa
what two cells are found in the lamina propria of GI tissue
stromal cells and fibroblasts
how is surface area increased in small intestine
finger like projections
microvilli “brush border”
what is present within each microvillus?
capillary bed
lacteal
what is a lacteal
lymphatic duct responsible for absorbing fats
5 basic categories of useable food
carbs proteins fat vitamins minerals
when we eat carbs what form do we usually get from our diet
polysaccharides
disaccharides
DO NOT get monosaccharides
what form does carb have to be in to be absorbed into the blood
monosaccharide
polysaccharides
starch
glycogen
cellulose
disaccharides
sucrose
lactose
maltose
monosaccharides
glucose
fructose
galactose
where are ectoenzymes and what do they do
ectoenzymes are bound to the membrane of the brush border in the intestine
break down disaccharides to monosaccharides
ex: lactase
how are monosaccharides absorbed through the intestinal tissue
- Na/K pump creates Na gradient
- Na high outside cell, low inside cell, will want to move into cell - Na and glucose symporter pumps into cell (SGLT1)
- Fructose will follow concentration gradient and diffuse into cell (GLUT5)
- GLUT2 transporter will move glucose, fructose, galactose into blood
what effect do sweetners have in the absorption in the SI
increase expression of GLUT2 transporter
proteins are broken down into
amino acids
where are 2 locations proteins are broken down
stomach
small intestine
what proenzyme is produced in the stomach
pepsinogen
pepsinogen
proenzyme
converted to pepsin by HCl in stomach
what does HCl do to make proteins more susceptible to enzymes in the stomach
unravels the proteins
what enzyme releases proenzymes into the small intestine for digesting proteins
pancrease
what are the proenzymes of the small intestine
trypsinogen
chymotrypsin
procarboxypeptidase A and B
proelastase
why is trypsinogen so important
cleaved to trypsin by enteropeptidase
trypsin essential for peptide breakdown because activates all the other proenzymes of the intestine