WEEK 5: LIPIDS Flashcards
What are the most common types of lipids found in food?
triglycerides
Definition pertaining to triglycerides formation and breakdown.
Esterification: joining 3 fatty acids to a glycerol unit
De-esterification: lipolysis of adipose tissue stores: releases FA from glycerol: resulting in FFA
Re-esterification: reattaching FA to glycerol (absorption)
How are trans fat found in food created?
Through partial hydrogenation of polyunsaturated FA = more rigid and compact
Lipids are transported in the circulation via lipoproteins. Describe the characteristics, composition and role of the four main lipoproteins
- Chylomicrons: transport fat through the lymhatic system
SI-Liver 2-7% cholesterol
2 VLDL: triglycerides - carries lipids fromliver to cells - LDL: cholesterol from liver to cells
- HDL: cholesterol from cells to liver
Chylomicrons are a type of lipoprotein = lipid care + shell composed of specific apolipoprotein, phospholipids and free cholesterol
What are the chemical characteristics and specific physiological function of dietary fatty acids?
FA saturated unsaturated trans poly mono
What is an example of a rich food source for each of the types of fatty acids?
long chain: 12+ carbons beef, pork, lamb and most plant oils
medium chain: 6-11 carbons coconut and palm kernel oil
short chain: less than 6 carbons
3% of fat in butter
What are plant sterols? How can they reduce dietary cholesterol absorption?
Chemically similar to dietary sterols but can’t be converted to steroids in body. 40+ types
Incorporated in micelles during absorption - bind to same receptors - reduce the amount of dietary cholesterol that iss absorbed
found in whole grains, fruits, veges, legumes
also absorbed via NPC1L1, released back into the limen via proteins ADCGS, travel to colon for excretion
Examples of EFA What are the precursors?
omega 6 precursor: linoleic acid e.g. vegetable and sunflower oils LA, GLA, AA omega 3 precursor: alpha linoleic acid e.g. green leafy veges ALA, SDA, ETA, EPA
Functions of EFA’s?
Important structural components of cell membranes:
DHA and EPA
- Keep membranes fluid and flexible
- DHA: Needed during fetal life and infancy for:
-Normal development and function of retina
-Normal development and maturation of nervous
system
- Needed throughout life for:
-Regulation of nerve transmission and
communication
-Important signaling for gene expression
Precursor of cholesterol synthesis? What are key players in the synthesis?
Acetyl CoA + acetoacetyl CoA
HMG CoA reductase
What are eicosanoids? How are they made?
- signaling molecules made by the enzymatic or non-enzymatic oxidation of arachidonic acid or other polyunsaturated fatty acids (PUFAs) that are, similar to arachidonic acid, 20 carbon units in length.
Most eicosanoids are produced from arachidonic acid, which is a polyunsaturated fatty acid that you get from eating foods like animal fats. They have many effects on your body, including inflammation, fever promotion, blood pressure regulation, and blood clotting.
How can oats reduce circulating cholesterol?
contain Beta glucans - macrophage activation end up excreting more cholesterol - increase the production of bile, prevents recycling to bile, bind to bile acids - increase excretion
What are the dietary guidelines for fat intake for the general healthy adult population?
AMDR: total fat 20-35% of estimated energy requirement
saturated and transfats should be imited to no more than 10%
low density omega 3 fat should equate to 0.2% of Estimated energy requirment
Describe the digestion, absorption and transport of dietary triglycerides
triglycerides: 3 fatty acids + glycerol unit
triglycerides in micelles are broken down into monoglycerides and free fatty acids by pancreatic lipase
short/med chains FA - directly into BS
long/= mono glycerides - absorbed through brush border enzymes - reformed as triglycerides
What are 6 enzymes involved in the digestion of lipids?
lingual lipase gastric lipase pancreatic lipase phospolipase A2 cholesterol lipase bile salts (CKK) - emulsifies fat
