Fat storage Flashcards
(40 cards)
Where are triglycerides and cholesterol esters synthesised?
Smooth ER
What makes up VLDL?
Triglyceride and cholesterol
Apoprotein B
Where is apoprotein B synthesised?
Rough ER
What is function of microsomal TAG transfer protein?
Add lipid components to Apoprotein B
What is rate limiting for VLDL production?
FA *
State process of Fatty Acid export?
1) Apoprotein B (ApoB) synthesised in rough ER
2) Lipid components (TG, Cholesterol esters) synthesised in smooth
ER
3) Microsomal TAG transfer protein adds lipid components to ApoB
4) Transported in vesicle to Golgi
5) ApoB is glycosylated
6) Glycosylated Apo’s with lipid components bud off golgi
7) Migrate to sinusoidal membrane of hepatocyte
8) Vesicles fuse with the membranes and VLDL is releasd
Where is ApoB glycosylated?
Golgi apparatus
Where does glycosated Apo with lipid component migrate to?
Sinusoidal membrane of hepatocyte
What occurs if excess intake triglycerides?
1) Triglycerides reach liver
Accumulation
What function of lipogenesis?
Produce triglycerides from acetyl-CoA subunits
Triglycerides used as energy reserve
Stored in adipose tissue
What controls lvls of lipogenesis?
Insulin
What is rate limiting step in lipogenesis?
Acetyl-coA to malonyl-coA
What catalyses lipogenesis?
Acetyl CoA carboxylase
Does lipogenesis increase or decrease during fasting?
Reduce
Hepatic glycogen stores depleted
Triglycerides broken down in adipocytes
Free FA released
Is lipogenesis anabolic or catabolic?
Anabolic
Store
Where are FFA oxidised for energy source?
Liver
Where do lipids flow into liver from? (3)
1) Portal vein
2) Heptatic artery
3) Lymphatics
In what form are lipids transported to liver? (4)
1) Triglycerides
2) Lipoproteins
3) Chlyomicron remnants
4) HDLs
5) FA bound albumin
How are lipids uptaken into adipocyes?
Triglycerides can’t diffuse through cell membrane
1) Lipoprotein lipase breaks down triglycerides
2) Release free fatty acids
3) Fatty acids are lipophilic so diffuse through bilayer
4) Facilitated transport into the cells
What are the 3 transport systems for fa into liver? (3)
1) Fatty acid binding protein (mitochondrial AST)
2) Fatty acid translocase (FAT)
3) Fatty acid transport polypeptide (FATP)
Can triglycerides diffuse through membrane?
If not what can?
No
FFA can
What enzyme breaks down triglycerides
Lipoprotein lipase
What occurs do FA in adipocytes?
Re-esterified to triglycerides
Stored
Where does FA move after adipocytes?
Hepatocytes