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Fat Metabolism - Essential Fatty Acids
last 14 slides for final exam
Definition of Essential fatty acids:
Unsaturated fatty acids that cannot be synthesized in human cells, so must be acquired from the diet; includes linoleic and α-linolenic acid.
Name the essential fatty acids
linoleic acid (LA, 18:2 n-6)
alpha-linolenic acid (ALA, 18:3 n-3)
Why cant humans synthesize the essential fatty acids?
Humans cant form double bonds ("desaturation" by desaturases) beyond the delta 9 position in the hydrocarbon chain.
(humans lack delta 12 & 15 desaturases, that insert double bonds at these positions)
Linoleic acid n-6 (LA) & alpha-linolenic acid n-3 (ALA) compete for the same ________ & ________ ___________ for synthesis of longer PUFA, such as ______ & _________.
They compete for the same ELONGASE & DESATURASE ENZYMES
for synthesis of Arachidonic Acid (AA) and Eicosapentaenoic Acid (EPA)--- PUFA's
What is the preferred substrate of delta-6 desaturase?
alpha-linolenic acid (ALA) -- n-3
If ALA (n-3) is the preferred substrate, why is it important for Americans to increase their n-3 FA's?
Because excess dietary LA (n-6): ALA (n-3) [greater than 10:1] results in greater net formation of AA than EPA.
Humans are believed to be physiologically adapted to a _______ ratio of n-6:n-3 fatty acids?
Humans physiologically adapted to 1:1 ratio.
If the amt of AA (n-6) in cell membranes is much greater than the amt of EPA (n-3), then......
more eicosanoids will be synthesized that are derived from AA than EPA.
Eiconsanoids are fatty acids having ____ carbons, and include _____, _____, and _______.
20 carbon FA
prostaglandins, thromboxanes, and leukotrienes.
Eicosanoids are derived thru the hydrolysis of the _______ PUFA from membrane ___________; fatty acids present reflect ____________.
reflect dietary intake
Eicosanoids derived from __________ are less potent inducers of inflammation, blood vessel constriction, and coagulation than eicosanoids derived from _________.
Eicosanoids derived from EPA (n-3) are less potent inducers of _________, __________, & __________ than eicosanoids derived from AA (n-6).
inflammation, blood vessel constriction, and coagulation
_____________ are generally considered "________"(lower blood lipids) and "________" (reduce blood clotting).
Omega 3 fatty acids (n-3)
To increase n-3 fatty acid intake, the American Heart Assoc. recommends consumption of ________ at least _____ times weekly?
fish, particularly oily fish, 2 times/week
Higher dietary n-3 fatty acid intakes are associated with ____________ risk.
reduced cardiovascular disease risk
Increasing n-3 fatty acid intake can decrease the risk of _________ and ________ in individuals with ________.
decrease risk of myocardial infarction and sudden cardiac death in individuals with coronary heart disease (CHD)
Increasing intake of what 2 fatty acids may be beneficial to individuals with _________. Esp those with elevated __________.
EPA and DHA diabetes
Fish oil supplementation decreases ________ and reduces the requirement for _____________ medication in ___________ patients.
Preliminary data suggests that n-3 fatty acid supplementation may be beneficial in treatment for what three conditions?
depression, bipolar disorder, and schizophrenia
Individuals who are chronically exposed to cold may have more _______________ tissue.
Brown Fat thermogenesis is due to:
Uncoupling protein (UCP aka thermogenin) that creates pores that allow H+ to move out of the intermembrane space into the matrix, creating heat instead of ATP.
How is brown adiposw tissue different from white?
-Mitochondria are structurally different (provide more heat production rather than ATP)
What can stimulate brown fat thermogenesis?
-chronic exposure to cold