Regulation of Carbohydrate/Fat Metabolism and Exercise Effects Flashcards
what are the fast fiber types
type 2 myosin a and b
what are the slow fiber types
type 1 myosin
what color are type 1 myosin fibers and why
redder in color due to the large amounts of myoglobin
describe the contents of type 1 fibers
contain large numbers of oxidative enzymes, more mitochondria, and are surrounded by more capillaries
describe the energy and fatigue properties of type 1 fibers
large capacity for aerobic metabolism and high resistance for fatigue
where can type 1 fibers be found and what is their function
generally postural muscles and used for endurance
what are type 2a fast oxidative fibers made of
a hydrid of type 1 and type 2
describe type 2a fast oxidative fibers
red in color and contain large amount of mitochondria
what respiratory pathway do type 1 fibers use to make ATP
aerobic metabolism
what pathway do type 2a fibers use to make ATP
aerobic and anaerobic metabolism
describe type 2b fast glycolytic fibers
white in color, low levels of myoglobin and few mitochondria
what pathway do type 2b fast glycolytic fibers use to make ATP
anaerobic metabolism
what can influence the composition of muscle fiber types
training and genetics
what is the fatigue rate of the muscle fiber types in order of low fatigue to high fatigue rate
slow twitch, fast twitch oxidative, fast twitch glycolytic
what is the energy source used during the first hour of exercise
muscle glycogen provides 50% of energy, muscle triglycerides and plasma free fatty acids are 25% each
what is the energy source used during exercise in the second hour of exercise
blood glucose and plasma free fatty acids provide most as muscle glycogen and triglycerides are being depleted faster than they can be replaced
what energy source is used during the 3rd hour of exercise
blood glucose and plasma free fatty acids
what energy source is being used during hour 4 of exercise
blood glucose and plasma free fatty acids. muscle glycogen is fully depleted and muscle triglycerides provide less than 10% of energy needs
which muscle fiber type provides more force
fast twitch
what is maximal tetanic force
maximum force a muscle can generate
what is specific force
max force divided by muscle cross sectional area, looks at how much the individual myofibril can contract
what does myostatin or GDF8 do
inhibit muscle differentiation and growth
what does loss of myostatin lead to
increased muscle size
describe the myostatin protein
member of the TGF beta superfamily and binds to the activating type 2 receptor
how does specific force change in loss of myostatin
it is lower because max force is the same but the muscle size is bigger
what do endurance and resistance training result in
a shift from fast 2b myosin to 2a, although changes are small and do not result in a complete conversion
describe sarcopenia and how to limit it
loss of muscle mass with aging. 2 phases: 10% lost from age 25-50 then rapid loss after age 50. regular exercise can limit or reduce age related muscle loss
what happens to muscle mass in paralysis or disuse
atrophy
explain the role of ATP in muscle contraction (power stroke)
myosin is attached to actin, as contraction takes place ADP and phosphate are released, ATP binds and muscle fiber returns to steady state with ATP back to ADP and Pi
describe the structure of glycogen
-it is a glycoprotein
-consists of a core protein “glycogenin”
- highly branched structure made of glucose molecules connected through 1,6- and 1,4- glycosidic bonds
what enzymes are involved in glycogen synthesis
branching enzyme and glycogen synthase
what enzymes are involved in glycogen breakdown
glycogen phosphorylase and glycogen debranching enzyme
explain how diets affect muscle performance
carbohydrate rich diets display longer or extended muscle performance times
what is the cori cycle
muscle uses glucose in glycolysis for energy which makes lactate. lactate goes to the liver to be converted back to glucose to be used for energy again
why are trigylcerides highly concentrated stores of metabolic energy
they are reduced and anhydrous
what is the main reason muscles use glucose for energy instead of fatty acids
fatty acids require molecular oxygen and aerobic respiration is slower
what substances stimulate lipolysis
glucagon, corticosteroids, ACTH, and catecholamines
what inhibits lipolysis
insulin
what are the 4 steps of beta oxidation of fatty acids
oxidation
- hydration
- oxidation
- thiolysis
what does EPO do
stimulates red blood cell production which would translate to a greater supply of oxygen to tissues but it also thickens blood and increases strain on the heart
how many ATPs can you generate under aerobic conditions
38
how mnay ATPs can you generate in anaerobic respiration
2
what is carnitine used for
the transport of fatty acids from the cytosol into the mitochondria during the breakdown of lipids
what are fat deposits used for
contain triglycerides used during porlonged exercise as muscle glycogen is depleted and energy demands cannot be met by glucose
what is “hitting the wall”
a condition caused by depletion of glycogen stores in the liver and the muscles which causes sudden fatigue and reduction in energy
in glycogen breakdown what are the terminal residues that are released
first residue is glucose, subsequent ones are glucose-1-P
what do the terminal residues do after being released
glucose combines with glucose-1-p to form glucose-6-P which feeds into glycolysis
how long do glycogen and glucose stores provide energy to sustain biological function
24 hours
how long do triacylglycerol stores allow for survival
several weeks
what do peripheral tissues do with fatty acids
-storage
- exported as VLDL
- or undergoes beta oxidation to enter krebs cycle
what do peripheral tissues do with fatty acids
-storage
- exported as VLDL
- or undergoes beta oxidation to enter krebs cycle
what substrate does each step of beta oxidation use
-oxidation: FAD
- hydration: H2O
- oxidation: NAD+
-thiolysis: CoA
what does insulin do to ACC? glucagon?
insulin stimulates, glucagon inhibits
