AND 330 Phosphocreatine-ATP Energy System

Phosphocreatine-ATP energy system

most immediate available energy source, process is rapid, doesn't require any special structures, used during first ~15 secs of exercise, can occur without O2

creatine phosphate

high energy phosphate group similar to ATP, energy released by breakdown of PCr not used directly to accomplish cellular work

How does PCr rebuild ATP and how frequently?

PCr rebuilds ATP to keep a relatively constant supply by donating a phosphate group to ADP to form ATP

How long can intramuscular PCr stores supply energy for?

intramuscular PCr stores can only supply energy requirements during max exercise for a very short time

When is Creatine reversibly phosphorylated to PCr?

during rest and when energy demand for ATP is reduced

Equation for PCr system

ATP + Creatine --> PCr + ADP

What enzyme is used for the reaction of creatine to PCr?

creatine kinase

Is this a paradox?

dietary nutrients used to regenerate ATP during recovery from exercise

What is a supplementary way to regenerate ATP?

When ATP and PCr are depleted, ATP can be formed by generating 2 ADP molecules together

What is the equation for the supplementary reaction?

ADP + ADP --> ATP + AMP

What enzyme is used in the supplementary reaction

adenylate cyclase

During rest, what happens?

ATP changes to ADP, Creatine is changed to Phosphocreatine

During exercise, what happens?

Phosphocreatine changes to creatine, ADP changes to ATP, with a muscle contraction ATP then changes to ADP + Pi