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
carbohydrate vs lipid metabolism
carbs = much more rapid at generating ATP
lipids = have greater store of energy
integration of metabolic pathways
plasma lipoproteins
carry triacylglycerol & cholesterol esters
apolipoproteins
membrane protein = recognition sites on lipoproteins
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
Apolipoproteins in Alzheimer’s
Apolipoprotein E (APOE) is a membrane protein on lipoproteins
- 3 APOE isoforms – each person carries 2 alleles
- APOE e3 commonly carried
- APOE e4 linked with increased risk of Alzheimer’s
risk of carrying APOE e4 genotype
pathogenesis
development/progression of a disease
Adipose tissue in lean vs obese people
adiponectin
- increase lipid oxidation
- improve insulin sensitivity
- lowers inflammation
effects of exercise on lipids
- exercise improves lipid profile
- increase adiponectin levels
- lowers inflammation
why is obesity so complex?
