1 Energy Systems Applied Anatomy and Physiology Flashcards
Adrenosine Triphosphate (ATP)
The only usable form of energy in the body
Sarcoplasm
The site where aerobic respiration takes place
The conversion of fuel into energy takes place in one of three pathways which are
Aerobic system
Anaerobic glycolytic system
ATP-PC system
What are the by-products of the aerobic system
Water
Carbon dioxide
The complete oxidation of glucose can produce how many ATPs (aerobic system)
38 (net 36)
The aerobic system has 3 stages which are
Glycolysis
Krebs Cycle
Electro transport chain
Glycolysis
the breakdown of glucose into pyruvate
net 2 ATP for every glucose molecule
What happens to the pyruvate so it can move to the next stage of the system
The pyruvic acid is oxidised into two acetyl groups and is then carried into Kreb’s cycle by coenzyme A
Krebs Cycle
the two acetyl groups combine with oxaloacetic acid to form citric acid.
hydrogen is removed from the citric acid and the now rearranged form of citric acid undergoes oxidative carboxylation
the carbon forms carbon dioxide which is transported to the lungs and breathed out
the hydrogen is transported to the electron transport chain
the result of these reactions result in the production of 2 ATP molecules
what is the electron transport chain
the hydrogen from the krebs cycle is carried to the electron transport chain by hydrogen carriers
the hydrogen splits into hydrogen and electrons and they are charged with potential energy
the hydrogen ions are oxidised to form water while the hydrogen electrons provide the energy to re-synthesise ATP
throughout this process 34 ATP are formed
Beta oxidation
when stored fat is broken down into glycerol and free fatty acids
the fatty acids then undergo a process called beta oxidation where it is converted to coenzyme a (the entry molecule for the krebs cycle)
3 Advantages of aerobic system
more ATP can be produced (36 molecules)
there are no fatiguing by-products
lots of glycogen and triglyceride stores so exercise can last for a long time
2 Disadvantages of aerobic system
Complicated system so cannot be used straight away.
It takes a while for enough oxygen to become available to meet the demands of the activity and ensure glycogen and fatty acids are completely broken down
Whats the fuel of the ATP-PC energy system
Phosphocreatine
Phosphocreatine
an energy rich phosphate compound that can be broken down quickly and easily to release energy and re-synthesise ATP
ATP-PC system
anaerobic process
re-sythesises ATP when the enzyme creatine kinase detects high levels of ADP
Equation for how PC releases energy
PC –> Pi + C + energy
this energy is then used to convert ADP to ATP in a coupled reaction
Energy –> + Pi + ADP –> ATP
For every PC how much ATP do you get
1 molecule of ATP
4 Advantages of the ATP-PC system
ATP can be re-synthesised rapidly
phosphocreatine stores can be-synthesised quickly
no fatiguing by products
possible to extend the time the atp-pc system can be utilised through use of creatine supplementation
Disadvantages of the ATP-PC system
there is only a limited supply of phosphocreatine in the muscle cell, only can last for 10 seconds
one mole of ATP can be re-synthesised for every mole of PC
PC re-synthesis can only take place in the presence of oxygen
Anaerobic Glycolytic System
an energy system that provides energy for high-intensity exercise and for longer than the atp-pc system (between 2-3 minutes)
How does the anaerobic glycolytic system work?
starts with anaerobic glycolysis
where PC stores are low and the enzyme glycogen phosphorylase breaks down the glycogen into glucose and then further broken down into pyruvic acid by PFK where the product of this reaction is 2 ATP
the pyruvic acid is then further broken down LDH
where does the anaerobic glycolytic system take place?
Sarcoplasm
Advantages of anaerobic glycolytic system
ATP can be re-synthesised quickly due to very few chemical reactions
lasts longer than the ATP-PC system
in the presence of oxygen, lactic acid can be converted back into the liver glycogen or used as a fuel through oxidation into carbon dioxide and water
it can be used to produce an extra burst of energy
Disadvantages of the anaerobic glycolytic system
lactic acid as the by-product means enzymes become denatured and prevents them from increasing the rate of reaction
only a small amount of energy can be released from glycogen under anaerobic conditions
Duration each energy system lasts and their intensities
ATP-PC system depletes after 8-10 seconds of maximal intensity
Anaerobic glycolytic system lasts between 2-3 minutes of repeated max intensity efforts
Aerobic system 3 minutes + at a sub-maximal intensity
What is the energy continuum?
A term which describes the type of respiration used by physical activities. Whether it is aerobic or anaerobic respiration depends on the intensity and duration of the exercise
How do slow twitch muscle fibres produce energy?
The main pathway for ATP production is in the aerobic system
It produces the maximum amount of ATP available from each glucose molecule (up to 36 ATP)
Production is slow but these fibres are more endurance based so less likely to fatigue
How do fast twitch muscle fibres produce energy?
The main pathway for ATP production is via the lactate anaerobic energy system
ATP production in the absence of oxygen is not efficient only two ATP produced per glucose molecule
Production of ATP this way is fast but cannot last for long as these fibres have least resistance to muscle fatigue
Oxygen consumption
The amount of oxygen we use to produce ATP
VO2 max
The maximum volume of oxygen that can be taken up by the muscles per minute
Sub-maximal oxygen deficit
When there is not enough oxygen available at the start of exercise to provide all the energy (ATP) aerobically
EPOC
The amount of oxygen consumed during recovery above that which would have been consumed at rest during the same time
Fitter athletes recover much faster
Fast Component of EPOC
The restoration of ATP and phosphocreatine stores and the resaturation of myoglobin with oxygen
Complete restoration of PC stores take 3 minutes and 30 seconds for 50%
Slow Component of EPOC
The oxygen consumed during the slow replenishment stage
Involves the removal of lactic acid. During recovery which takes up to 2 hours lactate converts back to pyruvic acid - this then is oxidised into co2 and water which can then be used as an energy source.
Lactate threshold
The point during exercise at which lactic acid quickly accumulates in the blood
OBLA
The point when lactate levels go above 4 millimoles per litre
Factors affecting the rate of lactate accumulation
Exercise intensity
Muscle fibre type
Rate of blood lactate removal
Respiratory exchange ratio
Fitness of the performer
Why do elite sprinters have better anaerobic endurance than non elite sprinters?
Body is more tolerant of high levels of lactate meaning they can work at higher intensities for longer
Muscles have adapted to training (incr mitochondria, higher capillary density and more myoglobin)
Factors affecting VO2 max (7)
Physiological (separate card for more detail)
Training - can be improved 10-20% following period of aerobic training
Genetics - inherent factors limit possible improvement
Age - VO2 max declines with age
Gender - Men have higher vo2
Body Composition - High body fat decreases vo2 mac
Lifestyle - smoking, sedentary, poor diet and poor fitness can all reduce Vo2 max
Physiological factors that affect VO2 max
Incr max cardiac output, stroke volume/ejection fraction/cardiac hypertrophy
Incr haemoglobin, red blood cells, mitochondria, aveoli surface area and lactate tolerance
Calorimetry
The calculation of heat in physical changes and chemical reactions
Indirect calorimetry
Measures the production of CO2 and/or the consumption of oxygen
Lactate Sampling
Taking a tiny blood sample and a handheld device analyses the blood and indicates how much lactate is present
Direct gas analysis
Measures the concentration of oxygen that is inspired and the concentration of carbon dioxide that is expired
Cycle Ergometer
A stationary bike that measures how much work is being performed
VO2 Max Test
Bleep test, 12 minute cooper run and Harvard Step test are all tests that indicate a persons VO2 max
Direct gas analysis done on a treadmill, cycle ergometer or rowing machine provide more valid and reliable results
Respiratory exchange ratio (RER)
The ratio of carbon dioxide produced compared to oxygen consumed
Altitude Training
Usually done at 2500m+ above sea level where partial pressure of oxygen is lower
3 stages are aclimatisation, primary training and recovery
Body produces EPO which increases red blood cell count
Effects last for up to 14 days
HIIT
Short intervals of maximum intensity exercise followed by a recovery interval of low to moderate exercise
Plyometrics
Involves repeated rapid stretching and contracting of muscles to increase power
Speed, agility, quickness (SAQ)
Activities performed with maximum force at high speed, energy is provided anaerobically
