Lipids Flashcards
Where are Lipids stored?
Specialised tissue called adipose tissue, as well as muscle.
What are lipids?
Diverse biological compounds exisitng as adipose/large tissue, characterised by low solubility of water.
Types of Lipids and their function?
Fatty acids/Triaglycerols - energy source
Steroid - Cell siganlling and membrane function
Phospholipids - form membranes and are present at the interface between lipid and water.
Why lipids and Carbs differ?
Lipids are largely hydrophobic whereas Carbs are hydrophillic
What are phospholipids made of?
Glycerol unit connected by
two fatty acids and a phosphoric group
(attached to an alcohol) via ester bonds
What are Triacylglycerol made of?
One glycerol unit and 3 fatty acids connected by
ester bonds
Triacylglycerol digestion?
Lipid dropets are reduced in size via bile acids made in the liver and relased by gallbladder
Lipase in the intestinal lumne then hydrolyses the ester bonds to yield 2 fatty acids and a monoacylglycerol
They are then packaged into chylomicrons and sent to lymph nodes and then the blood to be distributed
What are chylomicrons?
Chylomicrons are a class of Lipoprotein, a single layer of phospholipids with a hydrophobic core, which once formed pass into extracellular space, then into lymphatic vessels and then into blood circulation
The outline of the breakdown of fats (Triacyglycerols) as fuel? (4)
Triacylglycerol stores are contained in lipid droplets within adipocytes
or muscle fibres (next to mitochondria) for short diffusion distance
lipolysis optimal during aerobic exercise due to 3 key enzymes in type 1 fibres
Exercise speeds us B-oxidation = fatty acid degradation in adipose tissue/muscle
The product of β-oxidation (acetyl coA) enters TCA cycle
3 enzymes which drive fat breakdown?
Adipose TAG Lipase (AGTL)
Hormone sensitive lipase (HSL)
Monoacylgylcerol acyltransferase (MGL)
What impacts does exercise have on rate of lypolysis? (4)
Increases within 5-10 mins in both adipose tissue and muscle.
FFA’s and glycerol from lypolysis leave adipocytes and enter the bloodtsream
FFA’s in muscle stay but from the adipose they are transported to the muscle via acid binding protein in the membrane
FFAs are used for B-oxidation in the muscle and used for triaglycerol synthesis in the liver, with glycerol also being used for gluconeogenesis
Process of Beta Oxidation?
3 step process activating and transporting FFA’s and the products, Acetyl CoA and NADH/FADH2 produced is used in TCA and ETC.
1 - FFA’s activate by reacting with CoA forming Acetyl CoA
2 - Once passed through the membrane Carnitine takes the Acyl group allowing transport to the mutochondrial matrix
3 - The Acyl chain is then taken from Carnitine to refrom Acetyl CoA inside the matrix
What are FFA’s carried by?
Albium
How does exercise affect beta oxidation?
Increase activity of enzymes involved, such as carnitine, which facilitates transport to the mitochondria.
Increases activity of AMP activated protein kinase AMPK which prevents acetyyl CoA decarboxylase
Increase blood flow to working muscle and uptake at the muscle
Stimulates lipolysis in muscle
Lipid use in exercise and contrast it with carbohydrate use?
Lipid stores are usually used in low-moderate exercise and more predominant in prolonged exercise when glycogen stores are depleted as it is the secondary energy store. When needed beta/lipid oxidation will occur however it is slower than carbs.
One cycle of β-oxidation can produce?
1 Acetylcholine CoA
NADH
FADH2
What happens to plasma fatty acid concentration during high intensity exercise (over 85% VO2max?)
Plasma fatty acid concentration decreases.
Which answer best describes a ‘healthy lipidemic profile’?
High HDL, Low LDL and Triglycerides
