Lecture 25 - Fatty acids as a fuel molecules 1 Flashcards
What is the basic structure of a fatty acid
A carbon chain (hydrophobic) attached to a carboxylic acid group (hydrophilic)
What are Triacylglycerols (TAG)
Molecules consisting of glycerol with three fatty acids attached
Lipids
Lipids are hydrophobic
- Phospholipids
- Sterols
- TAG
What is cholesterol esters
Cholesterol ester are cholesterol which is attached with fatty acids
What percentage of dietary lipids are TAGs
over 90% of lipids in food are TAG
Whta enzymes is responsible for digesting TAGs in the small intestine
Pancreatic lipase
What is the function of pancreatic lipase
It hydrolyses TAGS at position 1 and 3 of the glycerol backbone, releasing 2 FFAs and one monoacylglycerol (MAG)
What is a MAG
A glycerol molecule with one fatty acid attached, formed during the digestion of TAGs
How do bile salts aid in fat digestions
They solubilise fats by forming micelles, with hydrophilic sides facing out and hydrophobic sides facing in, providing surface area for digestion in aqueous environments. TAGs inside
Bile salts
- made from cholesterol from liver
- Stored in gall bladder as bile, then secreted into small intestine
Exogenous fatty acid digestion
Is from diet
- TAGs broken into MAG and 2 FFA
- Absorption of small micelles TAGs made
- TAGs packaged into chylomicrons in epithelial cells
What are Lipoproteins
Lipoproteins are complexes that transport lipids including TAGs around the body and help solubilise them for transport in blood
What is the role of lipoprotein lipase (LPL)
It hydrolyses TAGs in lipoproteins into fatty acids and MAG, which enter tissues for use as fuel or storage.
What does a lipoprotein contain
- Phospholipids
- Unesterified cholesterol
- Esterified cholesterol
- TAGs
- Apoproteins
Major classes of lipoproteins
- Chylomicrons - Low protein, TAG transport
- VLDL - medium protein, TAG transport
- LDL - cholesterol transport
What are chylomicrons
Lipoproteins that transport TAGs from the intestines to other tissues via the lymphatic system
What happens to chylomicrons after they deliver TAGs to tissues
Chylomicrons become remnants that are taken up by the liver for recycling or further processing
What is the primary role of VLDL
VLDL transports TAGs from the liver to peripheral tissues
What does LDL primarily transport
LDL primarily transports cholesterol to peripheral tissues
Why is fat a more efficient storage molecule compared to carbohydrates
Fatty acids are more reduced than carbohydrates, meaning they release more energy when oxidised.
What are the primary storage sites for TAGs in the body
TAGs are stored in adipose tissue as the main energy reserve
Why do red muscle cells prefer fatty as a fuel molecule
Red muscles are designed for endurances and tend to use fats, which provide sustained energy over long periods
Lipoprotein Lipase
Hydrolyses TAG in lipoproteins.
- Highest activity in heart and skeletal muscles and adipose tissue
How is LPL activated
By ApoCll on the chylomicrons
What is the consequence of a defect in ApoCll and LPL
Defects lead to elevated levels of chylomicrons and plasma TAG, as TAGs cannot be properly hydrolysed and utilised by tissue
Exogenous vs Endogenous pathway
Exogenous pathways involves lipids from diet, while endogenous involve lipids synthesised or recycled by liver
What are livers role
- Recycles remnants
- Makes VLDL
- Produced bile salts for digestion and LDL for cholesterol transport
What is B oxidation
A metabolic process that breaks down fatty acids in the mitochondria Matrix to generate acetyl CoA , which enters the citric acid cycles for ATP production
What happens to fatty acids that are not in TAGs for transport
Free fatty acids are bound to proteins such as albumin for transport in the blood for tissues where they are needed for energy production
Endogenous recycling LDL pathway
LDL
- Hepatic lipase form LDL from VLDL
How is LDL made
VLDL secretion and then VLDL remnants
