ch 6- fats Flashcards
If a double bond is present, it may be in one of two formations. What are the two formations?
cis, trans
are chains of carbon and hydrogen with a carboxyl group (a carbon with a double bond to oxygen and a single bond to an oxygen/hydrogen, written as COOH) at one end.
fatty acids
cis
groups that are on the same side of the double bond between carbons.
trans
groups that are on opposite sides of the double bond between carbons.
Polyunsaturated fatty acids can be further distinguished by their fatty acid series. This refers to
the presence of a double bond between carbons that is counted from the last carbon in the chain (farthest from the carboxyl group carbon). This terminal carbon is referred to as omega or n-.
triglyceride
3 FAs attached to a glycerol
names of omega 3 FAs
- a-linolenic acid
- EPA
- DHA
a-linolenic characteristics
essential FA that is widely distributed in food
- can be used to form longer FAs
sources of a-linolenic acid
- flaxseed and grapeseed oils
- green leafy veggies
- soybean canola and linseed oils
EPA characteristics
- eicosanoids made from EPA have antiinflammatory effects and inhibit the formation of eicosanoids made from arachidonic acid, which have pro inflammatory effects
sources of EPA and DHA
- salmon
- herring
- mackerel
- sardine
DHA characteristics
- membrane phospholipids
- eicosanoids made from EPA have antiinflammatory effects and inhibit the formation of eicosanoids made from arachidonic acid, which have pro inflammatory effects
Almost 95 percent of the fat found in foods is in the form of ____ the remaining fats in food are either ____ ___ ____
triglycerides; sterols or phospholipids.
Once absorbed, the monoglycerides and free fatty acids are
resynthesized into triglycerides
triglycerides are incorporated into _____ which transport fat via the lymphatic system.
chylomicrons
ketosis
catabolism of acetyl CoA
esterification
- formation of a TG
- occurs after FAs are taken up by adipocytes
lipolysis
- breakdown of a TG to FAs and glycerol
lipolysis is inhibited by
insulin
beta oxdation
conversion of FAs to acetyl coA
lipoprotein lipase activity is stimulated by
insulin
Fat storage in muscle occurs primarily in muscle that is
highly aerobic
advantages of fats
- energy dense
- 9 kcal/g
- anhydrous
Within an adipocyte, hormone-sensitive lipase will
break down a stored triglyceride into glycerol and three fatty acids, which diffuse into the capillary circulation
FAs are bound to _____ for transport
albumin
epinephrine and norepinephrine stimulate
the process of TG breakdown and transport
mitochondrial transfer of fatty acyl coa
In the outer mitochondrial membrane, the CoA of fatty acyl-CoA is removed and joined to carnitine via carnitine acyltransferase. The acylcarnitine is then translocated into the mitochondria, where the fatty acid separates from the carnitine rejoins with a CoA.
ketones are produced by
liver
ketones supply how much of the bodys total energy needs after an overnight fast
2-6%
ketones are produced more when
FA oxidation is accelerated
when is FA oxidation accelerated (more ketones)
- low CHO intake
- impaired CHO metabolism
as intensity inc
the percentage of energy provided by fat metabolism decreases and that of CHO increases
as duration inc
the percentage of energy derived from fat may increase slightly as the percentage of energy derived from carbohydrate oxidation declines.
T or F Increases in body weight are due to long-term excess energy consumption.
true
general fat recommendations for athletes
1 g/kg
20-35% total caloric intake
total fat amount depends on
- total energy
- total CHO and protein
endurance athletes may need up to how much fat
2 g/kg/d
The appropriate amount of dietary fat for the athlete will depend on two factors—
overall energy (caloric) need and macronutrient balance
inadequate fat intake effects
- Inadequate replenishment of intramuscular fat stores
- Inability to manufacture sex-related hormones
- Alterations in the ratio of high-and low-density lipoproteins (HDL:LDL)
- Inadequate fat-soluble vitamin intakes
: May enhance free fatty acid mobilization during endurance exercise
caffeine
May increase blood flow to muscle-enhancing recovery
carnitine
: Suggested to increase fat and reduce carbohydrate oxidation during exercise
ketone esters
Suggested to reduce reliance on muscle glycogen stores
medium chain TGs
carnitine not effective for
inc fat metabolism
shows promise for athletes with exercise induced bronchoconstriction due to asthma
omega 3 FAs
caffeine is effective as
- CNS stimulant
- improving endurance performance and high intensity activities lasting 20 min
The predominant fat in food and the body is:
triglyceride
Which of the following is an essential fatty acid, one that cannot be manufactured in the body?
linoleic acid
Most long-chain fatty acids are absorbed from the intestinal mucosal cells in what form?
chlyomicrons
What is the enzyme found on the surface of blood vessels that catalyzes the release of fatty acids so they can be absorbed by fat and muscle tissue?
lipoprotein lipase
The human body normally stores approximately how much energy as fat?
100,000 kcal
A deficiency of carnitine in the body would result in fat metabolism decreasing for which of the following reasons?
Fatty acids would not be transported properly into mitochondria.
When the body is stressed by exercise, fat stored in adipocytes is:
mobilized
Which of the following is not true about fat metabolism?
As exercise intensity increases, the percentage of energy from fat decreases.
t or f: A person “burns” more fat as a percentage of total energy expenditure at rest.
true
t or f: As exercise intensity increases, the total (absolute) amount of fat used for energy increases, reaches a peak, and then decreases.
true
t or f: To “burn” more fat in a fixed period of time, a person should exercise at a low, “fat-burning” intensity.
true
Which of the following statements about an athlete’s dietary fat intake is true?
As long as carbohydrate and protein needs are met, athletes do not need to pay attention to their fat intake.
What are the adverse consequences of inadequate fat intake?
- inadequate fat-soluble vitamin intake
- inability to produce sex-related hormones
- inadequate replacement of intramuscular triglycerides
The appropriate amount of fat for training and performance depends on:
both overall energy need and macronutrient balance.
Why would an endurance athlete limit the amount of fat in a precompetition meal?
delays gastric emptying
The mechanism by which caffeine most likely improves endurance performance is that it:
decreases perception of exertion.
Why do athletes consume medium chain triglycerides (MCT) as a dietary supplement?
They are easily and quickly digested and absorbed compared to other fatty acids.
