Anaerobic metabolism

Question 1

What are the two anaerobic pathways?

Answer 1

Phosphocreatine pathway and glycolysis

Question 2

What is PCr?

Answer 2

A high energy phosphate compound similar to ATP

Question 3

Why can the body not just use ATP hydrolysis to supply energy?

Answer 3

Cells hold only enough ATP for 1-2s of VPA

Question 4

How does PCr in cells compare to ATP?

Answer 4

Cells hold 5-6 * more PCr than ATP

Question 5

How long can PCr reserve sustain VPA?

Answer 5

=<12 seconds; ~60m sprint

Question 6

How does PCr provide energy?

Answer 6

Creatine kinase catlyses PCr + ADP + Pi –> Cr + ATP

Question 7

How is PCr regenerated?

Answer 7

By ATP created in oxidative phosphorylation

Question 8

Where can Cr be sourced?

Answer 8

Meat, fish and poultry (4-5g/kg); CrH2O2 capsules/powder/liquid

Question 9

How do CrH2O2 supplements affect Cr levels?

Answer 9

High dose (20-30g) increases muscle Cr up to 30%; levels remain elevated for few weeks after supplemented for just a few days

Question 10

How can the body synthesise Cr?

Answer 10

From non-essential amino acids: arginine, glycine, methionine

Question 11

What are possible implications of Cr supplementation?

Answer 11

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

Question 12

What is the overall equation for glycolysis?

Answer 12

glucose + 2NAD+ + ADP + Pi –> 2pyruvate + 2ATP + 2NADH + 2H+ + 2H2O

Question 13

What is glycolysis important for?

Answer 13

Exercising skeletal muscle, retina, kidney medulla, RBCs

Question 14

How many enzymatic reactions are there in glycolysis?

Answer 14

10

Question 15

What are the two phases of glycolysis?

Answer 15

Phase one/ preparatory phase: involves 2 priming reactions; energy investment phase. Phase two/ payoff phase: involves 1 oxidation, 2 forming reactions; energy forming phase.

Question 16

What occurs during phase one?

Answer 16

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

Question 17

What occurs during phase two?

Answer 17

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

Question 18

How can glycogen enter the glycolysis pathway?

Answer 18

Glycogenolysis: (glucose)n + Pi –> (glucose)n-1 + G-1-P (glycogen phosphorylase); G-1P –> G-6-P (phosphoglucomutase); @ liver, G-6-P –> glucose + Pi

Question 19

How do the products of glycolysis differ when start substrate is glycogen?

Answer 19

Only requires 1 ATP in prep phase = net yield of +3 ATP

Question 20

How else can glycogenolysis be used?

Answer 20

Can provide glucose for bloodstream during hypoglycaemia

Question 21

What does the fate of pyruvate depend on?

Answer 21

Oxygen status of cell

Question 22

What occurs to pyruvate when cellular conditions are aerobic?

Answer 22

Oxidised in mitochondria to yield more ATP

Question 23

What occurs to pyruvate when cellular conditions are anaerobic?

Answer 23

Further oxidation is impeded; pyruvate reduces to lactate/ethanol and NADH is oxidised to NAD+ to continue glycolysis

Question 24

What is hyperlactatemia?

Answer 24

When lactate rises up to 5mmol/l

Question 25

What is lactic acidosis?

Answer 25

When lactate rises above 5mmol/l; often due to hypoxia associated with shock or cardiac failure

Question 26

What is the energy continuum?

Answer 26

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+