Macronutrient Metabolism Final
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The 3 major fat sources in the U.S. food supply as of 2005 are?
- -Shortening (25.6%)
- -Salad/cooking oils (25.1%)
- -Meats (16.5%)
A triglyceride is composed of what?
Glycerol and three fatty acids
What is the delta system?
- -18:2 Δ9,12First number:the number of carbons
- Second number: the number of double bonds
- Superscripts: carbons at which the double bonds are located from the carboxyl end
What is the omega system?
- 18:2 ω-6
- first number: the number of carbons
- second number: the number of double bonds
- third number: carbon number where the (first) double bond is located from the methyl end
What is the fatty acid is consumed in the greatest quantity?
What are the omega 6 fatty acids?
Linoleic acid, arachadonic acid, and γ-linolenic acid
What are the omega 3 fatty acids?
α-linolenic acid, EPA, and DHA
food sources of saturated fat
desserts, shortening, cooking oils, butter, cheese, fatty meats
What is the benefit of MCT?
they bypass the regulated steps in β-oxidation resulting in less fat storage and more fat being burned as fuel
positives and negatives of coconut oil, recommended use in clinical setting?
- positive: oxidized more readily, antimicrobial, high in MCTs
- negative: not many studies, increases LDL cholesterol, increases endotoxin(?)
- use in clinical setting: not enough evidence to support recommendation for use
what are trans fatty acids?
fatty acids that are produced during hydrogenation (a process used to solidify vegetable oils) it changes the configuration from a cis to a trans formation.
True or False: Trans fats are saturated fatty acids
False: they are unsaturated fatty acids, they do not lose the double bond when reconfigured.
Which fatty acids lower or have no impact on LDL cholesterol?
Stearic acid, Oleic acid, and Linoleic acid.
MUFA, omega-9, 18:1 Δ9
MUFA, trans-fat, 18:1 Δ9
PUFA, omega 6, 18:2 Δ9,12
PUFA, Omega 3, 18:3 Δ6,9,12
PUFA, 20:4 Δ5,8,11,14
Eicosapentaenoic acid (EPA)
PUFA, 20:5 Δ 5,8,11,11,14,17
Docosahexaenoic acid (DHA)
PUFA, 22:6 Δ 4,7,10,13,16,19
How do SFA and Trans Fatty acids cause an increase inflammation?
SFA stimulates TLR4 which increases NF-κb to increase TNF-α and IL-6 (which increase inflammatory response).
What are the two essential fatty acids?
- linoleic acid (Omega-6)
- alpha linolenic acid (Omega-3)
- *they help regulate blood pressure, blood clotting, immune function, and other body processes
Good food sources of omega 3
flax seeds, canola oil, walnuts, avocado, salmon, chia seeds
What is the primary enzyme responsible for breaking down fat?
gastric and pancreatic lipase
what digestion of lipid occurs in the stomach?
gastric lipase cleaves FA from sn-3 leaving a free FA and a diacylglycerol
Where are bile acids made?
In the liver from cholesterol
Explain TG digestion in the small intestine
bile is released by the gallbladder after stimulation by CCK. Trypsin stimulates procolipase to colipase which bind to pancreatic lipase helping it function in the small intestine to cleaves the sn-1 and sn-3 FA.
explain the digestion of phospholipids
trypsin activates phospholipase A2 which cleaves FA at sn-2 leaving a lysophospholipid and a FA
explain the digestion of Cholesterol
cholesteryl esterase (carboxylester lipase) cleaves the FA from the cholesterol leaving a free FA and Cholesterol
What is the role of micelles in lipid absorption?
Micelles allow fats through the unstirred water layer into the intestinal epithelium.
Explain the process of lipid absorption?
Once in the intestinal epithelium the fats bind to transport proteins that bring them to the ER where B48 helps package them into chylomicrons. The chylomicrons then enter the lymph.
What are the three enzymes involved in Lipogenesis?
- Acetyl CoA Carboxylase (ACC)
- Fatty Acid Synthase (FAS)
- Stearoyl CoA Desaturase (SCD)
Explain the role of Acetyl CoA Carboxylase (ACC)
- -Rate-limiting enzyme
- -It is highly regulated: stimulated by Citrate, inhibited by LCFA, Phosphorylation decreases ACC activity
- -End product (Malonyl CoA) is important in regulation of β-oxidation.
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