Chapter 3-Bioenergetics Flashcards
Catabolism
anabolism
exergonic reactions
endergonic reactions
breakdown of larger molecules
building up of molecules
energy releasing reactions
require energy
metabolism
total of all the catabolic and anabolic reactions in a biological system
hydrolysis
breakdown of 1 molecule of ATP to yield energy
requires one molecule of water
anaerobic
phosphagen and glycolytic systems do not require oxygen and occur in the sarcoplasm of the cell
only carbs can be metabolized into energy without the direct involvement of oxygen
aerobic
krebs cycle, electron transport, and the rest of the oxidative system require oxygen and occur in the mitochondria of the cells
phosphagen system
short-term, high intensity activities
highly active at the start of exercise
relies on hydrolysis and breakdown of creatine phosphate
limited by the small storage of CP
law of mass action
the concentrations of reactants or products in solution will drive the direction of the reactions
glycolysis
breakdown of either glycogen stores in muscle or glucose from blood to resynthesize ATP
not as rapid, but greater capacity due to greater supply of carbohydrates
pyruvate
end result of glycolysis
can be converted to lactate which results in faster resynthesis of ATP
can be shuttled to mitochondria to undergo the Krebs cycle with a shorter resynthesis rate due to greater number of reactions but can occur for longer duration
metabolic acidosis
process of an exercise-induced decrease in pH
may be responsible for the peripheral fatigue that occurs during exercise
lactate accumulation
normal range is 0.5 to 2.2 mmol/L at rest
increases with exercise intensity
maximal rate of production is twice as much for Type II (0.5 mmol/g/s) compared to Type 1 (0.25 mmol/g/s)
severe fatigue may occur at blood concentrations between 20-25 mmol/L
influenced by exercise intensity, muscle fiber type, exercise duration, state of training and initial glycogen levels
ATP yield
substrate-level phosphorylation during glycolysis yields 4 ATP
when it begins with blood glucose, 2 ATP are used, 4 are resynthesized for net gain of 2
when it begins with muscle glycogen, 1 ATP is used, 4 are resynthesized for net yield of 3 ATP
Allosteric regulation
allosteric inhibition
allosteric activation
end product of a reaction feeds back to regulate the turnover rate of key enzymes in the metabolic pathways
an end product binds to the regulatory enzyme and decreases its turnover rate and slows product formation
an activator binds with the enzyme and increases its turnover rate
regulatory enzymes in glycolysis
hexokinase, PFK and pyruvate kinase
Lactate threshold
exercise intensity at which blood lactate begins an abrupt increase above the baseline concentration
typically begins at 50-60% of maximal oxygen uptake in untrained individuals and 70-80% in aerobically trained athletes
OBLA
onset of blood lactate accumulation
second increase in the rate of lactate accumulation noted at higher relative intensities
occurs when the concentration of blood lactate reaches 4 mmol/L
oxidative system
primary source of ATP at rest and during low-intensity activities
primarily uses carbs and fats as substrates
at rest, 70% of ATP is from fat and 30% from carbs
as intensity increase, these ratios change
during high-intensity almost 100% of energy comes from carbs
oxidative phosphorylation
glycolysis and the Krebs cycle
40 total, but uses 2 ATP for a net gain of 38 ATP
phosphagen
concentrations are more rapidly depleted during high-intensity anaerobic exercise
resting concentrations may be increased with training
primary limiting factor during high intensity exercise
glycogen
300-400g are stored in muscle, 70-100g in liver
training can increase resting levels
repletion of muscle glycogen during recovery is related to ingestion
optimal levels are 0.7 to 3.0 g carbs per kg body weight every 2 hrs after exercise
Interval training
method that emphasizes bioenergetic adaptations for a more efficient energy transfer within the metabolic pathways by using predetermined intervals of exercise and rest
allow for more training at higher intensities
which substance can be metabolized anaerobically
glucose
the reaction that is the primary cause of metabolic acidosis
breakdown of ATP releasing P and H
which energy system produces ATP at the quickest rate
phosphagen
how many net ATP are produced via the oxidative energy system from the metabolism of 1 glucose molecule
38
which energy substrate cannot be depleted during extreme exercise intensities/durations
ATP
