part 4: proteins and fats

the proteins we ingest are

big long polypeptide chains

what do long polypeptide chains have to be

broken down in order to be absorbed

what enzymes break down proteins

peptidases

where does protein digestion begin and why

stomach because it’s the first region we have a good amount of peptidase activity

what are the two different peptidases

endopeptidase and exopeptidase

endopeptidase

work by cutting polypeptides chains in center

what are the two endopeptidases

pepsin and trypsin

pepsin

secreted into stomach creating many small peptide fragments

trypsin

from the pancreas

exopeptidase

work on ends of polypeptide chains

what do exopeptidase cut off

individual amino acids or in some cases di/tripeptides and separate them from larger chains

what is an example of exopeptidase

carboxypeptidase

carboxypeptidase

from pancreas

where is absorption from protein

in small intestine epithelial cell

for absorption of proteins what do you want

amino acid which is the simplest molecule

on apical membrane we have…

a whole host of transporters that are important for moving these products of digestion

aminos acids in protein digestion are transported by

amino acid sodium symporters

proteins can be absorbed in what complex forms such as….

dipeptides and tripeptides

to absorb di/tripeptides you use….

hydrogen symporter

large proteins can be absorbed rarly because….

proteins can be antigens we can mount an immune response against

in rare cases babies will have large polypeptides through…

endocytosis

endocytosis

whole antibody gets engulfed by plasma membrane and brought into the cell and exocytosed into the bloodstream

most of the fats we eat exist as….

triglycerides

triglycerides is too….

complex to be absorbed

fats create problems because they are….

lipophillic

lipophillic

poor solubility in water

digestion of fats is in….

small intestine

digestion of fats starts with

very large fat droplets

what breaks apart large fat droplets

motility processes

large fat droplets are broken down into

small fat droplets

to prevent fats from coming back together the small fat droplets are….

emulsified

emulsification

coding with a chemical known as bile

bile

secretion produced by liver

bile makes the fat molecules…

amphipathic

when the fat is amphipathic it makes..

surface water soluble

when the surface is water soluble the fat droplets can be chemically attacked by…

water soluble lipases

lipase are secreted in…

pancreas

lipase breaks down…

triglycerides into free fatty acids and monoglycerides

free fatty acids and monoglycerides are still….

non polar molecules and lipophilic

free fatty acids and monoglycerides are still attracted…

to each other in simple form

micelle

reform a particle

when micelle gets close to membrane of intestinal epithelial cells the…

free fatty acids and monoglycerides are able to cross membrane through simple diffusion

lipids are soluble in

other lipids

what other components of bile are also transported into the intestinal epithelial cells

cholestrol

alli

weight loss drug

how does alli work

by inhibiting pancreatic lipase

what happens when you inhibit pancreatic lipase

blocks fat digestion through blocking absorption of fats

anything not absorbed from your digestive system

stays there until it gets excreted

absorption of fats start

once inside intestinal epithelial cells

fats still have to be absorbed because they are…

lipophilic molecules in an aqueous environment

the intestinal eptihelial cell is going to package the fat components with components of bile into a membrane bound particle called

chylomicron

chylomicron have to get…

exocytosed across basolateral membrane because of size

fats are too big for capillaries so they get absorbed into lymphatic vessels called….

lacteals

fats pass through what before circulation

entire lymphatic system