Fuels Flashcards
How does energy flow and recycle in ecosystems?
- sunlight provides energy
- energy is trapped in organic molecules
- organisms utilize the organic molecules to obtain energy
What are problems associated with energy use in muscle?
1) Avid consumption of ATP (by actomyosin ATPase and Ca2+ pump ATPase)
2) Metabolic rate increases 100-fold on activation
3) Depletion of ATP = rigor mortis
What are solutions to energy use in muscles?
1) Range of mech. to supply ATP (according to needs of speed + endurance)
2) Store lots of energy within each muscle cell
3) Range of fatigue mechanisms exist
How can we measure ATP and PCR (energy turnover) in humans?
• Needle biopsy rapid freezing – various assays for ATP, PCr, lactate, glycogen etc. • Invasive • Limited time points
How long does ATP last?
2 seconds
How is ATP re-synthesised from ADP?
1) Substrate Level phosphorylation
• enzyme transfers phosphate from organic molecule to ADP, yielding ATP
From-phosphocreatine
From-glucose (glycolysis and TCA cycle)
2) Oxidative phosphorylation
• energy from electrons pulled from organic molecules used to synthesize ATP
What is the eqaution for the CPK reaction?
ADP + PCr ⇋ Cr + ATP
Enzyme = creatine kinase (CPK)
What happens to ATP and PCr when 100s of electrical signals stimulate a human muscle?
- ATP falls but not dramatically
- PCr falls traumatically
What does the CPK reaction function to do?
1) Acts as a temporal buffer for ↓ATP:
2) Acts as a pH buffer: PCr + ADP +H+ <====> ATP + creatine
3) Acts as a spatial buffer to move ~P from mitochondria to crossbridge
4) Pi release stimulates glycolysis
5) Regulates [ADP] and drives Krebs cycle
6) ..but high Pi induces fatigue
Where does energy come from?
Can’t create or destroy
Always present - energy is only transferred
What is the role of PCr and Creatine?
PCr:
- high energy compound, broken down to make more ATP
- rapidly mobilisable reserve of high energy phosphates
Creatine:
- facilitated recycling of ADP in muscles and brain tissues
What are the effects of Creatine supplementation?
1) increased PCr conc
2) faster aerobic recovery
3) decreased deamination
2 ADP —> ATP + AMP
(Myokinase; AMP —> ammonia)
What is the hierarchy of energy supply?
ATP available - not much there
PCr very rapid re-supply - a lot more present
What are the energetic limitations of power?
Max power output a human can achieve falls as the duration of the effort increases.
1) limited by force-velocity relation and PCr used
2) limited by amount of glycolysis tolerated
3) limited by rate of breakdown of CHO and amount (O2 supply)
4) limited by rate of supply of FAs and not amount = low power output
Fats don’t give a high PO - need other things too
What are the side effects of anabolic steroids?
Men:
- baldness
- breast development
- shrunken testicles
- severe acne
Women:
- hair loss
- loss of breasts
- swelling of clitoris
- severe acne
