Fat Digestion Flashcards
What are the classes of lipid (x5)
Fatty Acid Triacylglycerol Phospholipid Glycolipid Steroids
In what form is the majority of fat we injest
Triacylglycerol
Where does fat digestion take place
Small intestine
What enzyme is responsible for fat breakdown
Pancreatic Lipase
Are triacylglycerols water soluble?
No
They are water insoluble (hydrophobic)
Is lipase water soluble
Yes (hydrophilic)
What are the essential FA and how are they obtained
Linoleic Linoleic acid (derives Omega 3)
In plants, fish and seeds
What is the breakdown product after lipase
Monoacyl glycerol and 2x FA
What does bile do
Its an emulsifying agent that breaks down large fat droplets into multiple smaller ones
What is a micelle
Fat dropets are surrounded by bile salts. They have a hydrophobic centre and a hydrophilic surface
What happens after micelle formation
The lipase can breakdown the monoacylglycerol and FA into Glycerol and free FA
How does the acidic microclimate of the gut wall help with FA transport
??
What happens to the glycerol and FA when in the Enterocytes
They are reformed into Triaylglycerols in the smooth ER and processed in the golgi apparatus for exocytosis into the lymphatic system
What happens to the triacylglycerols before they can be exocytosed into lymph
They are packaged with APOB-48 into chylomicrons
What are the constituents of a chylomicron
Phospholipid (9%)
Cholesterol (3%)
ApoB (1%)
How does a chylomicron pass into the lacteal
Between endothelial cells
It cannot pass through the capillary basement membrane)
How are Fat soluble Vitamins absorbed
Same absorpitve pathway as fat
How are water soluble vitamins absorbed
By passive diffusion or carrier mediated transport
What are the water soluble vitamins
B
C
Folic acid
How is Vitamin B12 absorbed
Binds to intrinsic factor in the stomach to create complex which is absorbed in the ilem
What happens if you dont have intrinsic factor
Pernicious (sickle cell) anaemia
How long does it take for symptoms of pernicious anemia to proliferate after body stops making intrinsic factor
3 years
Liver has a 3 years storage of intrinsic factor
How much of digested Iron is absorbed
10% daily intake
How does Iron enter enterocyte
DMT1 receptor on duodenal enterocytes
What happens once iron is in the enterocyte,
Some of it is incorporated into ferratin
The rest enters the blood
What happens to iron in the blood
It is bound to Transferrin
Why is iron bound to transferrin
It is extremely reactive so it prevents the formation of free oxygen radicals
What happens to Ferratin levels in Hyperaemia
Increased
What happens to Ferratin levels in Anaemia
Decreased (more iron is released to blood)
What is the life span of a enterocyte
5 days
What happens to the Ferratin contents when an epithelial cell dies
Its contents gets released into the blood.
