Fat Metabolism - Essential Fatty Acids

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23 terms · 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 ____________.

sn-2 PUFA
membrane phospholipids
reflect dietary intake

Eicosanoids derived from __________ are less potent inducers of inflammation, blood vessel constriction, and coagulation than eicosanoids derived from _________.

EPA (n-3)
AA (n-6)

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)
hypolipidemic, antithrombotic

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
serum triglycerides

Fish oil supplementation decreases ________ and reduces the requirement for _____________ medication in ___________ patients.

joint tenderness
anti-inflammatory medication
rheumatoid arthritis

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 adipose

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?

-Greater vascularity
-More mitochondria
-Mitochondria are structurally different (provide more heat production rather than ATP)

What can stimulate brown fat thermogenesis?

-chronic exposure to cold
-long-term overeating

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