Fat Metabolism, Interaction of Fat and Carbohydrate Metabolism, Exercise Training Effects Flashcards
what is the body’s most plentiful source of energy
stored lipid
lipids store ____ as much energy as CHO for an equal amount of ____
2x; weight
lipids are an important source of energy in what kind of exercise
prolonged mild to moderate intensity
2 sites of stored lipids
- adipose tissue
- intramuscular
source of lipids for metabolism
- circulating triglycerides from VLDL or chylomicrons
- TG stored w/in muscle
- circulating FFA mobilized from TG in adipose tissue
circulating TG from VLDL occurs when
after eating (postprandial)
95% of fat in the diet is
TG
5% of fat in the diet is
sterols (cholesterol) & phospholipids
structure of TG
glycerol backbone + 3 FA
lipolysis
the breakdown of fat in adipose or muscle tissue to FFA and glycerol
7 step overview of fat metabolism
- Mobilization
- Circulation
- Uptake
- Activation
- Translocation
- b-oxidation
- Mitochondrial Oxidation
- mobilization : important enzyme and what it does
hormone sensitive lipase
- stimulates lipolysis and promotes fat release into the blood
HSL is found within
adipose tissue
HSL is inhibited by
insulin
HSL is stimulated by
epinephrine and norepinephrine (catecholamines)
2: circulation: interaction btwn fat and blood and what this means for circulation of fat within the circulatory system
- FFA are insoluble in blood (blood is mostly water)
- transported by albumin
FFA transported in the blood by
albumin
- uptake : how do FFA enter the muscle cell
FFA enters via a specific receptor site on the sarcolemma, called fatty acid binding protein (FABP)
FABP are
a family of molecules that transport FA throughout the cell
- activation: what are the compounds that act on FFA in order to activate them
- CoA
- 2 ATP
- Acyl-CoA synthase
- translocation : activated FA must be transported into
mitochondria
- translocation: what facilitates the transfer of the activated FA into the mitochondrial matrix
carnitine acyltransferase (CAT)
where is CAT located
on the inner mitochondrial membrane
- beta oxidation: occurs in
mitochondrial matrix
- beta oxidation: action
removes 2 carbon atoms at a time to form acetyl-CoA, NADH+H, and FADH2 units from the activated FA
the last pair of carbons makes what
just acetyl CoA
- mitochondrial oxidation: steps
- acetyl CoA units enter krebs cycle
- NADH+H and FADH2 enter the ETC
fat breakdown is directly associated with
O2 uptake
what must be available to accept electrons in ETC
O2
number of acetyl CoA =
of carbons / 2
number of NADH+H and FADH2 =
(# of carbons/2) - 1
rate limiting enzyme for mobilization of FFA
HSL
strength of HSL activation is dependent upon
intensity & duration of exercise, fitness level, & time since last food consumption
strongest stimulators of HSL activation
catecholamines (inc during exercise)
NEP/EP also stimulate breakdown of
CHO
rate limiting enzyme for fat oxidation in muscle
CAT - it controls the amount of FA entering the mitochondria for oxidation
how does exercise effect circulating FFA levels
inc by 10-20 fold
best way to mobilize and use stored fat is to
exercise
without sufficient ____ to interact with ____ the krebs cycle slows
OXA; acetyl-CoA
depleting muscle glycogen effect
dec muscle max aerobic power output
fat burns in
the flame of CHO
low intensity uses primarily
fat
high intensity uses primarily
CHO
as training inc, the crossover point moves in what direction
to the right
as exercise intensity increase reliance of fat ___ while reliance on CHO ____
decreases; increases
even though high intensity exercises uses a smaller relative percentage of fat ….
you burn more calories, so you most likely burn more fat with higher intensity than you do with lower
as exercise duration increases reliance on fat ___ while reliance on CHO ____
increases; decreases
changes in lipid metabolism are related to ___ ___ rather than exercise intensity
exercise volume
1st training related change
inc # of mitochondria and inc activity of enzymes w/in the mitochondria
- which inc kreb’s, ETC, and beta oxidation enzymes, thus inc oxidation of fat
2nd training related change
inc fatty acyl-CoA synthesis
3rd training related change
inc levels of HSL and CAT, which improve cellular availability and transport of FA
4th training related change
inc TG storage and oxidation within the muscle
5th training related change
inc FA uptake by the muscle
how does training increase FA uptake by the muscle
capillary density inc in tissue, thus blood flow inc and better exchange of FA and O2
6th training related change
improved cardiorespiratory system that enhances O2 delivery to the muscle
why is enhancing o2 delivery to the muscle key
more oxygen, more quickly means you reach steady rate exercise more quickly and you have less reliance on anaerobic metabolism
- Less lactate production (less pH disruption & less stress on the system)
7th training related change
all of these changes lead to CHO sparing
- delay in onset of fatigue
- can exercise longer and harder and use more fat compared to pre training
