Lipids Flashcards
Are fats hydrophobic or hydrophilic?
Hydrophobic - water repelling
Name the 3 main types of lipids
- Triglycerides
- Phospholipids
- Sterols (multiple carbon ring structure)
Triglycerides are made up of…?
one glycerol group + 3 x fatty acids
Phospholipids are made up of…?
one glycerol + 2 x FA + phosphate + organic molecule
Triglycerides can be saturated or unsaturated. What does this mean and what are the two types of unsaturated fats?
Saturated = no double bonds
Unsaturated =
Monounsaturated - 1 double bond (includes omega 9)
Polyunsaturated = >1 double bond (includes omega 3 and 6)
Main functions of lipids?
Provide energy from food and store energy in body fat
Also: insulation, protection for organs and bones, hormones, structural component of cell membranes, cell signalling, conversion of vit D from sunlight
Linolenic acid is also known as what?
Omega 3
Linoleic acid is also known as what?
Omega 6
What’s the basic structure of a fatty acid?
chain of carbon and hydrogen atoms + acid group (COOH) + methyl group (CH3)
What is the goal of fat digestion?
dismantle triglycerides into small molecules that the body can absorb and use (monoglycerides, fatty acids and glyercol)
Fat digestion in the GI tract…
Mouth: some hard fats begin to melt; lingual lipase secreted
Stomach: churning disperses fat; gastric lipase hydrolyses a small amount of fat only
Small intestine: bile from gall bladder emulsified fat; pancreatic lipase breaks triglycerides into monoglycerides, gycerol and fatty acids to be absorbed
Large intestine: some fat and cholesterol trapped in fibre and exits in faeces
Percentage of total fats that should make up adult diet (recommendation)
20-35% of total energy intake
Characteristics of saturated fatty acids
solid at room temperature
stable
straight chemical structure
What are the 3 types of saturated fatty acids?
- short-chain fatty acids (2-5 carbons long), lots of health benefits, non-essential
- medium-chain fatty acids (6-10 carbons long)
- long-chain fatty acids (11-40 carbons long)
Dyslipidaemia (abnormal blood lipids) are a risk factor for what?
chronic diseases such as heart disease and stroke
they contribute to atherosclerosis
Some health benefits of monounsaturated fatty acids
- support memory and cognitive function
- structural integrity of cell membranes
- reduce blood clotting, oxidative stress, atheroma plaque formation, risk of gall stone formation
Some functions of polyunsaturated fatty acids
- cell membrane integrity and fluidity
- raise HDL cholesterol
*risk of adverse affects if consumed in high amounts
Phospholipids have X and X groups?
Choline and phosphate
An omega-3 fatty acid has its first double bond…?
Third carbon from the methyl end
What is the purpose of chylomicrons?
Transport dietary cholesterol and triglycerides via the lymphatic system to cells of the body including adipose tissue for storage and muscles for energy
Where are chylomicrons assembled?
in the intestinal epithelial cells
Which lipoprotein is the largest in size?
Chylomicron
What are the precursors for synthesis of the eicosanoids?
Long-chain polyunsaturated fatty acids
The oils found in walnuts, soybeans, flaxseed and wheat germ represent a good source of preformed…?
linolenic acid
What type of fat is lecithin?
Phospholipid
What is the hormone that signals the release of bile in fat digestion?
Cholecystokinin
