aerobic system
1) glycolysis in sarcoplasm of muscle cell
breakdown glucose to pyruvic acid. 1:2. PA oxidised into 2acetyl groups and carried to krebs cycle by coenzyme A
2) krebs cycle: 2AG diffuse into matrix of mitochondria. combine with oxaloatic acid forming citric acid. hydrogen removed and this new form of citric acid undergoes oxidative carboxylation = c&h given off. C forms c02 to lungs, h is taken to by hydrogen carriers ETC = 2ATP
ETC: occurs in cristae of mitochondria. H splits into H+ ions and electrons that are charged with potential energy. H+ oxidised to form water, electrons provide energy to resynthesise ATP = 34 ATP produced
other energy sources in aerobic system
fats in form of fatty acids and proteins in forms of amino acids are 2 other energy sources
beta oxidation: stored fat is broken down into glycerol and free fatty acids. these undergo a process (B.O) where they are converted in COEA which is entry molecule for krebs cycle and then fat metabolism follows same as glycogen
1mol fat produces more ATP than 1mol glucose = predominant energy source in long-duration, low-intensity exercise
advantages of aerobic system
- more atp can be produces
- no fatiguing by-products (co2 and water)
- lots of glycogen and triglyceride stores so exercise can last for a long time
disadvantages of aerobic system
- complicated system = cannot be used straight away as takes awhile for enough o2 to become available to meet demands of activity and ensure glucose and fatty acids are completely broken down
- fatty acid transportation to muscles is low and requires 15% more 02 to be broken down
ATP-PC system
enzyme creatine kinase detects high lvls of ADP and then breaks down PC into Pi+C+energy. This energy is used to convert ADP to ATP in a coupled reaction: energy+pi+adp=ATP
1:1
advantages of ATP-PC
- ATP can be resynthesised rapidly using ATP-PC system
- PC stores can be re-synthesised quickly (50%-30s, 100%-3mins)
- no fatiguing by-products
- is possible to extend the time the ATP-PC system can be utilised through the use of creatine supplementation
disadvantages of ATP-PC system
- only limited supply of PC in muscle cell = only last up to 8seconds
- only 1 mol ATP produced for every mol PC
- PC re-synthesis can only take place in presence of 02 (=when intensity is reduced)
anaerobic glycolytic system
enzyme phophorylase activated when PC stores are low to break down glycogen into glucose which is further broken down into pyruvic acid by enzyme phosphofructokinase by anaerobic glycolysis in sarcoplasm of muscle cell where 02 isn’t available.
then PA further broken down into lactic acid by enzyme lactate dehydrogenase (LDH)
anaerobic glycolysis produces energy used to re-synthesis ADP into ATP = 2mols ATP produced: 1mol glucose
last up to 2-3mins
advantages of anaerobic glycolytic
- ATP can be resynthesised quite quickly due to very few chemical reactions and last longer than ATP-PC
- in presence of o2, lactic acid can be converted back into liver glycogen or used as a fuel through oxidation into c02 and water
- can be used for a sprint finish
disadvantages of anaerobic glycolytic
- lactic acid as by-product = accumulation = denatures enzymes = prevents them from increasing rate of chemical reactions
- only small amount of energy can be released from glycogen under anaerobic conditions (5% compared to 95% in aerobic conditions)
define energy continuum
a term which describes the type of respiration used by physical activities.
depends on intensity of exercise
slow twitch fibres in ATP production
- main pathway for ATP production is in the aerobic system, therefore produces maximum amount of ATP available from each glucose molecule
- production of ATP is slow but more endurance based so less likely to fatigue
fast twitch fibres in ATP production
- main pathway for ATP production is via lactate anaerobic energy system (during glycolysis)
- ATP production in absence of oxygen isn’t efficient (only 2ATP mol produced)
- production of ATP this way is fast but cannot last for a long time as fibres have least resistance to muscle fatigue
define oxygen consumption
the amount of o2 we use to produce ATP
define VO2 max
the maximum volume of oxygen that can be taken up by the muscles per minute
define sub-maximal oxygen deficit
when there isn’t enough o2 available at state of exercise to provide all the energy (ATP) aerobically
define EPOC
the amount of oxygen consumed during recovery above that which would have been consumed at rest during the same time
fast component of epoc
alactacid
the restoration of ATP and PC stores and the re-saturation of myoglobin with oxygen
complete restoration of PC takes up to 3mins during which approx 3litres of o2 are consumed
