Regulation of Carbohydrate Metabolism and Exercise Flashcards
what systems does exercise involve? (4)
musculoskeletal
respiratory
endocrine
immune
what does increased breathing and heart rate provide? (4)
increased O2 and nutrients
eliminates CO2 and metabolic waste products
transport hormones
maintain body temp and acid-base balance
in response to demand, muscles (3)
change ability to extract O2
choose energy sources
eliminate metabolic waste
what are fast fibers composed of?
type 2 myosin (2a and 2b)
what are slow fibers composed of?
type 1 myosin
what are the main fiber types? (3)
type 1
type 2a
type 2b
what color are type 1 fibers? why?
red, due to large amounts of myoglobin
what do slow twitches contain? (2)
large numbers of oxidative enzymes
more mitochondria
do slow twitches or fast twitches surround more capillaries?
slow
type 1 fibers have a large capacity for
aerobic metabolism
type 1 fibers have a high resistance to
fatigue
generally, postural muscles are used for
endurance (marathon runners)
how do type 1 fibers generate ATP?
aerobic metabolism
what are type 2a fast oxidative fibers are a hybrid of
type 1 and type 2
what color are type 2a fibers?
red, but not as red as type 1
do type 2a fibers perform anaerobic or aerobic metabolism?
both to generate metabolism
contain large numbers of mitochondria
type 2b fast glycolic fibers are what color? why?
white, they contain low levels of myoglobin and few mitochondria
do type 2b fibers use aerobic or anaerobic metabolism?
anaerobic to generate ATP
what can influence muscle composition?
training and genetics
most are a combination of these two types
what is type 1 used for?
long distance
slow twitch
what is type 2a used for?
400m/800m
fast twitch oxidative
what is type 2b used for?
short sprints
fast twitch glycolytic
low fatigue to high fatigue
type 1
type 2a
type 2b
what does fiber type vary with?
exercise type
what do slow twitch fibers vs fast twitch fibers look like under a microscope?
slow: dark fibers
fast: white fibers
what provides energy during the start of exercise?
muscle glycogen ~50%
muscle triglycerides ~25%
plasma free fatty acids ~25%
what energy is used after one hour of exercise?
blood glucose and plasma free fatty acids provide more of the energy nutrients as muscle glycogen and triglycerides are being depleted
what energy is used after two hours of exercise?
muscle glycogen and triglycerides are being depleted faster than they can be replaced
blood glucose and plasma free fatty acids provide a greater and greater percentage
what energy is used after three hours of exercise?
> 70% of energy needs are being provided by blood glucose and plasma free fatty acids
what energy is used after four hours of exercise?
> 90% of energy fuel is provided by blood glucose and plasma free fatty acids
muscle glycogen is fully depleted and muscle triglycerides provide >10% of energy needs
at any given speed of movement, muscle groups with a high percentage of fast-twitch (FT) fibers exert more — than those with muscle groups that contain primarily slow-twitch (ST) fibers
force
muscle contractility can be measured and expressed as (2)
maximal titanic force
specific force generated
specific force
the max force divided by muscle cross sectional area
inhibitors of muscle differentiation (2)
myostatin
growth differentiation factor 8 (GDF8)
what does loss of myostatin lead to?
increased muscle size
what family is myostatin a member of?
TGF-beta
myostatin actives
type 2 receptors
in the case of the myostatin knockout muscle the max force is the same, but when corrected for the larger muscle size, the specific force is —, meaning
lower
individual muscle fibers are weaker
both endurance and resistance (weight) training result in a shift from
fast 2b myosin to 2a myosin
training induced changes are small and do not result in
complete conversion
aging is associated with a loss of muscle mass, known as
sarcopenia
loss appears to follow which two phase?
10% is lost from age 25-50
then a more rapid loss in muscle mass after age 50
what can reduce or limit age related muscle loss?
regular exercise
muscle loss also occurs with (2)
paralysis disuse atrophy (broken arm/leg)
— fibers have more ATP and cross bridges
fast
sources of ATP required for muscle contraction (4)
glycolysis
Krebs cycle
glycogenolysis
fatty acid oxidation
glycogen is a
glycoprotein
what does glycogen consist of?
a core protein glycoprotein
branching of glycogen
highly branched structure made of glucose molecules connected through 1,6 and 1,4 glycosidic bonds
during glycogen breakdown, the terminal residue is released as
glucose, subsequent ones as G1P
glycogen phosphorylase
removes glucose
glycogen deb ranching enzyme
breaks branches
muscle glycogen content was measured directly for the first time using a — — method
needle biopsy
using different diets, glycogen content of muscle could be changed dramatically from 0.6 g/100 g to 4.7 g/100 g for
protein and fat diet versus carbohydrate rich diet
diets were induced by first undergoing glycogen depletion
individuals fed the carbohydrate Ruch diet displayed longer or extended muscle performance times when maintained at 75% of their max — —
oxygen consumption
muscle glycogen content is a determinant of the capacity to do
long term heavy exercise
muscle glycogen content can be manipulated depending upon diet following
glycogen depletion
Type 0
glycogen storage diseases
glycogen synthase deficiency (muscle)
symptoms: cardiomyopathy and exercise intolerance associated with complete absence of muscle glycogen
type IXd (glycogen storage diseases)
muscle phosphorylase kinase deficiency
symptoms: x-linked disease, relatively mild disorder characterized by variable exercise induced muscle weakness or stiffness
why do we get cramps?
lactate builds up in the muscle
triglycerides are highly concentrated stores of metabolic energy because they are
reduced and anhydrous
the yield from oxidation of fatty acids is
9 kcal/g
the yield from oxidation of carbohydrates and proteins are
4 kcal/g
triglycerides are non polar and so are stored in nearly — form
anhydrous
more polar proteins and carbohydrates are more highly
hydrated
what is the major reason triglycerides were selected in evolution as the major energy reservoir?
fat stores more than 6x as much energy as glycogen
glycogen and glucose stores provide enough energy to sustain biological function for about —, whereas triacylglycerol allows survival for
24 hours
several weeks
metabolically, the enzymatic process of degradation of fatty acids to yield ATP energy requires
molecular oxygen
muscles burning fatty acids must do so aerobically or anaerobically?
aerobically, which is slower than burning glucose anaerobically and utilizing the cori cycle
4 steps of beta oxidation
oxidation
hydration
oxidation
thiolysis
weight is largely a function of how much
energy you consume versus how much you expend
doping induces performance enhancing drugs by
steroids to boost muscle growth, narcotics to suppress pain, beta blockers to slow the heart rate (particularly helpful for fine motor control) and stimulants to add pep
erythropoietin (EPO)
a naturally occurring hormone that is produced by the kidneys, which stimulates red blood cell production
EPO stimulates
red blood cell production which can increase strain on the heart
higher RBC counts should translate to a greater supply of
oxygen to tissues
