Digestion of triglycerides
- separated into small droplets
- bile acids and pancreatic lipases hydrolyze fats to free fatty acids & mono/di-glycerides
- abdorbed into the blood & attached to serum albumin
- absorbed into the intestinal cells and packaged into lipoproteins
Bile
Fluid released from the gall bladder to digest the foods we eat.
- made in the liver
- stored in the gall bladder
- emlusifying agent
(cholic acid is the major bile acid)
chylomicrons
partiallt digested mono and diglycerides absorbed and recomined into triglycerides and packaged into lipoproteins
Lipid transport
enter metabolism through three different sources:
- diet ( transported by chylomicrons)
- storage in adipose tissue (transported by serum albumin)
- synthesis in the liver ( transported by VLDLs)
- cholesterol from liver ( transported by LDLs)
- cholesterol form dead cells( tranported by HDLs)
Must eventually be transported in blood (in a carrier system)
lipoproteins
micelle that conatins trigylcerides and cholesterol.
- phospholipid
- protein around the surface
- cholesterol and cholesterol ester
- trigylceride
- Transport both fat and cholesterol
lipoprotein density
Mostly hydrocarbon, greater the fat the lower the density
- chylomicrons (lowest density)
- VLDLs (very low density lipoproteins)
- IDLs (intermediate density lipoproteins)
- LDLs (low density lipoproteins)
- HDLs (high density lipoproteins)
Good and bad cholesterol
- HDLs are called good cholesterol
- LDLs are called bad cholesterol
There is no such thing as good or bad cholesterol
Storage of trigylcerides
Stored in adipocytes
- fat must be disassembled to cross membranes
- after a meal insulin activates the synthesis of trigclycerides for storage
oxidation of fatty acids
- activation → by CoA
- transport→mitochondrial matrix
- oxidation →oxidized to produce acetly-CoA, NADH and FADH2
ß oxidation pathway
Purpose:
- oxidize fatty acids
- cut fatty acid into 2-Carbon pieces
Starting materials:
- Fatty acid-SCoA
- Free CoA,NAD+,FAD
Products:
- acetyl-CoA
- NADH, FADH2
triacylgycerol metabolism
only recognize triacylgycerol pathway
Thromboxane
- promotes blood clotting
Sphingomyelin
- forms cell membrane
ketogenisis
Synthesis of ketone bodies from acetyl-CoA
_Purpose: _
recycle acetyl-CoA back to free CoA
SM: 2 acteyl-CoA; Products: 2 free Co, 1 acetoacetate
Ketone bodies:
- when there is too much acetyl-CoA for the citric acid cycle to process ketone bodies are formed
- produced in the liver that can be used as fuel by msucles and the brain
lipogensis
synthesis of fatty acids from acetyl-CoA
- occurs in the cytoplasm
- when there is an excess of acetly-CoA
- regulated by insulin and glucagon
