Fat Digestion Module (Quiz) Flashcards
the fat that comes from our diet is mostly in the form of
which makes up the majority of fats
- triglycerides
- cholesterol
- phospholipids
- triglycerides
basic structure of triglyceride
- glycerol + 3 fatty acids
the fatty acid chains make up the hydro________ portion of the lipid and the glycerol makes up for the hydro________ portion of the lipid
- phobic
- philic
_______ are the backbone structure for all lipids and the target of enzymes that break down lipids in GI tract
- triglycerides
which are the essential vitamins that come from dietary fat
- ADEK
intestinal lining made up of multiple ______
- villi
within each villus there is a series of _____ as well as a single ________ which drains into the lymphatic system
- capillaries
- single lacteal
epithelium of each individuals villus contains a brush border of ________ which increases the absorptive surface area of intestines
- microvilli
the challenge for lipids in the intestinal lumen
- have to make them hydrophilic so they can be digested by hydrophilic enzymes and eventually absorbed
stages of lipid digestions
- emulsification
- lipolysis
- micellization
- packaging and transport of chylomicrons
what is emulsification
- breaking up large fat globules into smaller particles
where is emulsification initiated?
- in the small intestine
purpose of emulsification
- increase surface area of fat particles so they can be broken down in later stages
bile is mostly composed of _________
- water
what is the predominant solid portion of bile
- bile salts
importance of bile salts being strongly ionized
- allows them to be soluble
main phospholipid of bile
- lecithin
which parts of the bile are soluble in water
- polar parts of bile salts and lecithin molecules
how do we make the fat soluble in water?
- hydrophilic bile acid on top
- lecithin poking out
hydrolysis of lipids is done by cleavage of ______ bond in triglycerides
- ester bond
_______ lipase is found in saliva
- lingual lipase
________ lipase is secreted by ________ cells in the stomach
works best where
- gastric lipase
- chief cells
- acidic environments
problem with gastric lipase
- only cleave one side of the glycerol molecule
pancreatic lipase secreted by ____________
works best where
- pancreatic acinar duct cells
- alkaline environments
benefits of pancreatic lipase
- cleaves both sides of glycerol molecule
which lipase performs majority of lipolysis
- pancreatic lipase
what can inhibit lipases
how
- bile acids
- displaces lipase from fatty acid droplets
where is colipase secreted
- pancreatic acinar cells
purpose of colipase
- binds bile acids and lipase
- stabilizes presence of lipase on surface fat droplets to restore lipolytic activity
what is the purpose of micellization
- get the fat droplet into the intestinal epithelial cells
what can accumulation of free fatty acids in the intestinal lumen do
- block further lipolysis and digestion
what is critical micellar concentration
- concentration of bile salt at which micelle formation occurs
composition of micelle
- fatty acids inside
- polar and water soluble surface
composition of intestinal brush border
- slightly acidic unstirred water later
- brush border membrane
can single fatty acids get through the unstirred water layer
- no
purpose of acidity of unstirred water layer
- releases fatty acids from micelles
majority of absorption of fatty acids into intestinal bilayer done by
how about for larger molecules like cholesterol
- diffusion
- needs membrane proteins
are micelles truly required for fat absorption
what is their purpose
- no
- increase efficiency
purpose of chylomicron formation
- prevent free fatty acids from diffusing back across intestinal epithelium
metabolic trapping packages free fatty acids into
- triglyerides
- cholesterol esters
- phospholipids
- fat-soluble vitamins
reassembled lipids coated with proteins known as
purpose
- apolipoproteins
- chylomicron formation and export
resulting chylomicron transported where
by what process
- basolateral membrane of enterocyte
- exocytosis
can chylomicrons go directly into circulation?
where do they enter?
- no. too big
- lacteal within a villus
intestinal lacteals drain into the
which drains into
- thoracic lymphatic duct
- subclavian veins
