Anaerobic Energy Provision Flashcards
What is used for muscle contraction?
The energy from the hydrolysis of a high energy bond
ATP
Provides the chemical energy that can be converted into other forms of energy used by living cells
Energy for muscle contraction: ATP hydrolysed by myofibrillar ATPase.
Bioenergetics: Basic Energy Systems
ATP storage in the cell is very limited
The body must constantly synthesise new ATP
Three main synthesis pathways
The three main synthesis pathways
ATP-PCr (anaerobic metabolism)
Glycolytic system (anaerobic metabolism) - blood lactate
Oxidative system (aerobic metabolism) - balance of CO2 to O2, Douglas bags
What is Rigor Mortis?
Stiff muscle happens if you can’t generate new ATP to unbind myosin from actin
It happens for so long until the natural breakdown of death with breaks the muscle down as well
ATP-PCr system overview
1 mol ATP per 1 mol of substrate (PCr) = yield
Recycling ATP during exercise until used up (3-15s max exercise)
PCr energy CANNOT be used for cellular work
PCr energy CAN be used to reassemble ATP
How does the ATP-PCr system work?
Phosphocreatine is hydrolysed by Creatine Kinase into Creatine and inorganic phosphate
Free energy is used to bind ADP and the phosphate which forms ATP
What happens to phosphocreatine stores during hard exercise?
The harder you exercise the more you deplete phosphocreatine stores because the body is trying to keep the muscle ATP levels constant
Creatine (Cr) supplementation
PCr + ADP + H+ = Cr + ATP
ADP increases can be delayed - cross bridge cycling slowing improved.
Osmatic activity of creatine - higher cell water content = weight gain
The myokinase reaction
ADP + ADP = ATP + AMP (at the cost of 31 kJ/mol ADP)
Limited capacity to produce ATP
Only important during high intensity exercise (activated when pH falls)
AMP is an activator of enzymes involved in glycogen breakdown
The anaerobic glycolytic system
The breakdown of glucose/glycogen via glycolysis
2-3 mol ATP per mol of substrate (glucose or glycogen)
1-1.5 mol ATP per lactate molecule if all pyruvate is converted to lactate
Lasts 15s to 2 min
Enzyme control of creatine kinase
Controls the rate of ATP production in ATP-PCr system
Negative feedback system - When ATP levels decrease (ADP increases), CK activity increases
When ATP levels increase, CK activity decreases
Enzyme control of Phosphofructokinase (PFK)
Glycolytic system
Rate-limiting enzyme - decreases of ATP (increases ADP) = PFK activity increases
Increases of ATP = PFK activity decreases
Also regulated by products of Krebs cycle
How far can you run using only energy from PCr breakdown?
3-15s (<100 m)
How far can you run using only energy from anaerobic glycolysis?
15-120s (400 - 800m)
