Lipid Metabolism Flashcards
saturated vs non-saturated fatty acids
sterols
- type of lipid
- maintain cell structure & functions
- regulating fluidity
- e.g choleSTEROL
phospholipid
- cell membrane structure
triacylglycerol
- 90-95% lipids from dietary fat
- energy store in adipose tissue & muscle
- ester bonds
process of digestion & absoption of triaclyglycerol (TAG)
- Ingestion
o Large coarse lipid droplets reduced to lipid droplets by bile - Intestinal Lumen
o Pancreatic lipase hydrolyses ester bonds to yield:
2 fatty acids
2-monoaccylglycerol - Enterocytes
o Products freely enter intestinal cells where TAG is reformed - Bloodstream
o Lipids are packaged into chylomicrons
o Exported into lymph nodes then into the blood
chylomicrons
- class of lipoprotein
- single layer of phospholipids with a hydrophobic core
- transporting triglycerides and cholesterol
movement of chylomicrons to the blood
lipids are mainly stored in…
adipose tissue
(muscle = 0.2-0.8%)
adipocyte
- fat cell
lipolysis in skeletal muscle
- triacylglycerol stored in lipid droplets in muscle fibres (next to mitochondria)
- key enzymes located in type 1 muscle fibres
- lipolysis optimal during aerobic exercise
β-oxidation
- breaking down long fatty acids that have been converted to acyl-coA chains into progressively smaller fatty acyl-CoA chains
- Acteyl CoA can then be passed on to TCA/Krebs cycle
- 4 reactions = 1 cycle
3 major enzymes for traicylglycerol breakdown
- Adipose TAG lipase (AGTL
- Hormone sensitive lipase (HSL)
- Monoacylglycerol acyltransferase (MGL)
yield of 1 cycle of β-oxidation
1 x acetyl-coA TCA cycle
1 x FADH2
1 x NADH
1 x acyl-coA
Exercise speeds up fatty acid oxidation by…
- Stimulating lipolysis in adipose tissue & muscle
- Increasing blood flow to the working muscle = increasing FFA delivery
- Enhancing translocation of fatty acid binding protein at the plasma membrane (FABP-PM) for FFA uptake into muscle
- Increasing activity of AMP-activated protein kinase (AMPK) which deactivates acetyl coA carboxylase which reduces fatty acid synthesis
blood plasma fatty acid profile during exercise
integration of metabolic pathways
types of lipoprotein fat transporters
Chylomicrons
- Mainly carry TAG
Very low density lipoproteins (VLDL)
- Mainly carry TAG
Low density lipoproteins (LDL)
- Mainly carry cholesterol
High density lipoproteins (HDL)
- Mainly carry cholesterol to the liver
order of lipoprotein fat transporters + location
risk of carrying APOE e4 genotype
Adipose tissue in lean vs obese people
why is obesity so complex?
