Chapter 3: Bioenergetics Flashcards
Define bioenergetics
The conversion of macronutrients into usable forms of energy
Catabolism
The breakdown of molecules resulting in a release of energy
Anabolism
The synthesis of larger molecules. Requires energy
What are the two types of reactions?
Exergonic and endergonic reactions
What are Exergonic reaction?
energy-releasing reactions. Catabolism
What are endergonic reactions
requires energy. anabolism
What is left after ADP hydrolysis?
ADP –> AMP, P, and H
Phosphagen System: Key points 1
The synthesis of CP and ADP to form ATP. Catalyzed by CK
Phosphagen System:
Key points 2
Uses CK reactions to maintain ATP concentration
What law controls the phosphagen system?
Law of mass action: The concentration of the reactants or products drive the direction of the reaction
(i.e. increased ADP causes an increase in ADP rephosphorylation into ATP by CP)
Glycolysis System:
Key point 1
Breakdown of Carbs to resynthesize ATP
What is the end product of glycolysis? And what is its “fate”?
Pyruvate.
-Can either be converted into lactate and enter fast glycolysis
-Or get shuttle to the mitochondria into the krebs cycle and undergo slow glycolysis
“slow” vs “fast” glycolysis
Fast: ATP resynthesis occurs at faster rate but doesn’t last as long
Slow: ATP resynthesis occurs at a slower rate but lasts longer
What is involved in the Cori cycle?
The conversion of lactate into glucose in the liver
What is the energy yield after glycolysis?
Glucose –> 2
Glycogen –> 3
What occurs in the slow glycolysis?
Pyruvate converted into Acetyl-Coa and enters the krebs cycles.
NADH molecules enter the ETC for further resynthesis of ATP
What is lactate threshold?
The exercise intensity or % VO2 max where an abrupt increase in lactate is seen
What does the lactate threshold represent?
an increased reliance on anaerobic mechanisms
What is Onset blood lactate accumulation (OBLA)
The second marker of an abrupt increase in lactate (~ 4 mmol/l)
What is the lactate threshold for untrained vs trained individuals?
50-60% vs 70 to 80%
The oxidative system: Key points 1
Primarily fueled by CHO and fats
Describe fat oxidation
Triglycerides are broken down into free fatty acids by hormone sensitive lipase. The free fatty acids then undergo beta oxidation in the mitochondria of the muscle fibers and are converted into acetyl- CoA and H. Acetyl-CoA enters the krebs cycle and H atoms are carried by NADH and FADH2 into the ETC
Protein oxidation
Broken down in amino acids and converted into glucose, pyruvate of enter into Krebs cycles
What controls the oxidative system?
-Isocitrate dehydrogenase is stimulated by ADP and inhibited by ATP
- the rate of the Krebs cycle is determine by the availability of NAD and FAD
- the ETC is stimulated by ADP and inhibited by ATP
Phosphagens: CP depletion
- CP decrease 50-70% during the fist stage of high-intensity exercise. Can almost be eliminated during very intense exercise to exhaustion
Phosphagens: Repletion
-CP = 8 min
-ATP = 3-5 min
Glycogen Depletion
The rate is related to exercise intensities. Can become completely deplete in muscle cells during exercise
Glycogen repletion
Comes from food. Aim for 0.7 to 3 g per kg ever 2 hours
