Energy Metabolism and Bioenergetics Flashcards
Nutrients from foods are stored as
carbohydrates, fats and proteins
Bioenergetics
The process of producing energy (ATP) in a biological system and using ATP to do work
Metabolism
All the chemical reactions in the body
Thermodynamics
Energy neither created and destroyed
Exergonic reactions
energy-releasing reactions (free energy negative)
Endergonic reactions
energy-consuming reactions (free energy positive)
Metabolic Pathway- Metabolism
Total of all the catabolic/exergonic and anabolic/endergonic reactions in the system
Catabolic pathway
Breakdown of larger molecules into smaller molecules
Anabolic pathway
Synthesis of larger molecules from smaller molecules
ATP
Metabolic currency in biological tissues
Three sources of ATP Production
- ) Phosphocreatine (PCr)
- ) Oxidative Phosphorylation ( mitochondrion)
- ) Glycolysis
Phosphocreatine
- Immediate source lasts only a few seconds at maximal flux
- Occurs in the cytoplasm
- Does not require O2, anaerobic metabolism
Glycolytic (uses glucose)
- At maximal flux, only lasts up to a few minutes before muscle fatigue occurs
- Occurs in the cytoplasm
- Anaerobic in that oxygen is not used, but pyruvate moves into mitochondria to supportive oxidative phosphorylation
Oxidative phosphorylation
- Can support exercise for hours
- Occurs in the mitochondria
- ‘Aerobic metabolism’
- Slower form of ATP production because it is so complexed, however it’s the most efficient
ATP-Phosphocreatine (ATP-PCr)
ATP + Cr ⇌ ADP + PCr + H+
- The reaction is bi-directional depending on substrate level concentrations
- During skeletal muscle contraction, there is an ⬆️ in the concentration of ADP and H+ and a ⬇️ in ATP
- If PCr is available, the reaction will work to restore ATP
- PCr replenishment can take between <5-15 mins
- Still used at low and moderate intensity exercise, but can replenish at same time using ATP produced in mitochondria
Glycolysis
- When exercise continues for more than a few seconds, ATP regeneration is derived from blood glucose and muscle glycogen stores
- Converts glucose (6 carbons) into 2 molecules of pyruvate ( 3 carbons) and a net of 2 ATP
- PFK is also known as the ‘rate of liminting enzyme’ : regulates the interaction between F6P and F1,6 biphosphate
- In the glycotic process there are also 2 NADH which
are formed that can be used in aerobic metabolism to produce additional ATP
Anaerobic and Aerobic Glycolysis
- If O2 is present (aerobic condition), pyruvate can enter the Krebs cycle
Using ATP produces Acid
During exercise ATP is used by: - Cross-bridge cycling (myosin ATPase) - Action potentials (Na/K ATPase) - SR calcium uptake ATP 'hydrolysis' is A MAJOR SOURCE OF ACID BUILD UP DURING EXERCISE
What causes metabolic acidosis in skeletal muscle?
Acidosis develops when the rate of H+ production exceed the rate of H+ removal/buffering
Electron Transport Chain
- Complex 1 is a stonger magnet than NADH
- Complex 2 is a stronger magnet than FADH2
- Complex 4 is the strongest of them all for proteins
- O2 is a magnet
- Everytime you have an electron going through the ETC, you pump 3 protons through complex 1,3 and 4
- If your O2 is limited, the mitochondria won’t benefit you