Anaerobic metabolism Flashcards
What are the two anaerobic pathways?
Phosphocreatine pathway and glycolysis
What is PCr?
A high energy phosphate compound similar to ATP
Why can the body not just use ATP hydrolysis to supply energy?
Cells hold only enough ATP for 1-2s of VPA
How does PCr in cells compare to ATP?
Cells hold 5-6 * more PCr than ATP
How long can PCr reserve sustain VPA?
=<12 seconds; ~60m sprint
How does PCr provide energy?
Creatine kinase catlyses PCr + ADP + Pi –> Cr + ATP
How is PCr regenerated?
By ATP created in oxidative phosphorylation
Where can Cr be sourced?
Meat, fish and poultry (4-5g/kg); CrH2O2 capsules/powder/liquid
How do CrH2O2 supplements affect Cr levels?
High dose (20-30g) increases muscle Cr up to 30%; levels remain elevated for few weeks after supplemented for just a few days
How can the body synthesise Cr?
From non-essential amino acids: arginine, glycine, methionine
What are possible implications of Cr supplementation?
MAY: increase rate of ATP resynthesis; delay depletion of PCr; decrease dependence of glycolysis and thus reduce LA accumulation; increase training intensity. DOES: associate with renal disease; increase glycogen and water retention; have side effects of vomiting, nausea, and GI disturbance
What is the overall equation for glycolysis?
glucose + 2NAD+ + ADP + Pi –> 2pyruvate + 2ATP + 2NADH + 2H+ + 2H2O
What is glycolysis important for?
Exercising skeletal muscle, retina, kidney medulla, RBCs
How many enzymatic reactions are there in glycolysis?
10
What are the two phases of glycolysis?
Phase one/ preparatory phase: involves 2 priming reactions; energy investment phase. Phase two/ payoff phase: involves 1 oxidation, 2 forming reactions; energy forming phase.
What occurs during phase one?
Glucose + ATP –> G-6-P + ADP; G-6-P –> F-6-P (phosphoglucoisomerase); F-6-P + ATP –> F-1,6-BP + ADP; F-1,6-BP –> glyceraldehyde-3-phosphate + dihydroxyacetone phosphate; DHAP –> GALP
What occurs during phase two?
Is repeated for each GALP. GALP + Pi + NAD+ –> glycerate-1,3-BP + NADH+ H+; glycerate-1,3-BP + ADP –> glycerate-3-P + ATP; glycerate-3-P –> glycerate-3-P; glycerate-2-P –> phosphorenolpyruvate + H2O; phosphorenolpyruvate + ADP –> pyruvate + ATP
How can glycogen enter the glycolysis pathway?
Glycogenolysis: (glucose)n + Pi –> (glucose)n-1 + G-1-P (glycogen phosphorylase); G-1P –> G-6-P (phosphoglucomutase); @ liver, G-6-P –> glucose + Pi
How do the products of glycolysis differ when start substrate is glycogen?
Only requires 1 ATP in prep phase = net yield of +3 ATP
How else can glycogenolysis be used?
Can provide glucose for bloodstream during hypoglycaemia
What does the fate of pyruvate depend on?
Oxygen status of cell
What occurs to pyruvate when cellular conditions are aerobic?
Oxidised in mitochondria to yield more ATP
What occurs to pyruvate when cellular conditions are anaerobic?
Further oxidation is impeded; pyruvate reduces to lactate/ethanol and NADH is oxidised to NAD+ to continue glycolysis
What is hyperlactatemia?
When lactate rises up to 5mmol/l
What is lactic acidosis?
When lactate rises above 5mmol/l; often due to hypoxia associated with shock or cardiac failure
What is the energy continuum?
ATP hydrolysis provides energy for maximal intensity exercise, e.g. MVC, for 1-2 seconds. PCr metabolism provides energy for very high intensity exercise, e.g. 100m sprint, for 10-15s. glycolysis provides energy for high intensity exercise, e.g. 400-800m run, or for MVPA, e.g. 1500m run, for 15s- 3-4mins. Krebs and oxidative phosphorylation provides energy for low-moderate intensity exercise, e.g. 10-42.2km runs, for 3mins+
