ATP anaerobic metabolism, glycolysis and high intensity sports Flashcards
Phosphocreatine
PCr in muscle can be used to reynthesise ATP at very high rates
Limited capacity
PCr restricted to cytoplasm where it is present at a concentration of about 20 mol.kg ww
Glycogenolysis
Glycogen breakdown
Glycogenesis
Glycogen synthesis
Getting glucose into cells
There are 5 different types of glucose transporter
GLUT 4 is stimulated by insulin present in muscle
GLUT 2 is not stimulated: present in liver (which needs to export glucose in fasting when insulin is low)
ATP hydrolysis equation
ATP + H20 —-> ADP + P + hydrogen + energy
Phosphocreatine degradation
Phosphocreatine breakdown is initiated immediately at the onset of contraction
PCr utilisation is at its highest within 2 seconds of the imitation of contraction
As the rate of PCr breakdown declines, so does the rate of ATP resynthes
The glycolytic pathway
- Starting point is glycogen
- First reaction involves splitting off the large glycogen molecule of a single glucose molecule which is released as glucose 1 phosphate and this is rapidly converted to glucose 6 phosphate
- First step catalysed by enzyme glycogen phosphorylase
- Phosphate group added to the glucose molecule that is added to the glucose molecule from the cell- primes the glucose molecule for subsequent reactions
- Glucose present in the blood can be taken up by muscle cells and used in glycolysis
- GLUT 4 transports glucose from the blood to muscle fibres
- Glucose 6 phosphate then converted to fructose 6 phosphate
- Net gain from anaerobic glycolysis is 2 ATP molecules starting from glucose
Phosphofruktokinase
An important enzyme in all living cells
Performs the committed step in the glycolytic pathway- conversion of fructose 6 phosphate
Acids and bases
Using ATP produced hydrogen
Lactic acid causes drop in PH
Why is acidity in the muscles an issue
Affects calcium transport, rate of glycolysis, fatigue
Bicarbonate buffering
Achieved by the infection of a dose of about 0.3g NaHCO3 per kg body mass
Can neutralise some of the excess acidity in muscles
Allows hydrogen to leave muscles faster
This allows more hydrogen and lactate to be produced before muscle acidity reaches limiting levels
Oxidation of carbohydrates
Carbohydrate converted to pyruvate by glycolysis
Pyruvic enters mitochondria and TCA cycle
Entry of pyruvate molecules into the mitochondria
Further metabolism of pyruvate catalysed by the enzyme pyruvate dehydrogenase
To prime the pyruvate molecule for subsequent reactions, it is attached to a molecule of co Enzyme A and at the same time one of the carbon atoms is lost as carbon dioxide, yielding acetyl co a
Oxidation of amino acids
Some amino acids can be oxidised
Amino group must be removed by transferring it to another molecule called a keto acid resulting in the formation of a different amino acid
this process is called transamination
Or amino group can be removed to form free ammonia
Keto acid eventually oxidised to cos and h20 in TCA
Oxidation of fat
Free fatty acids from adipose tissue, some intramuscular fat
Fat has to be used to be oxidised to be used
2 carbon units sequentially removed by free fatty acids via beta oxidisation to generate acetyl co A
acetyl co A
Lipolysis
The breakdown of triglyceride into its fatty acid and glycerol components
