Transcript ATP ENERGY PRODUCTION

ATP ENERGY PRODUCTION
Energy
• The body needs a constant supply of energy to
perform every day tasks such as respiration
and digestion.
• Energy is the capacity to perform work and is
measured in joules or calories.
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Calorie, Joule and Watt
• Calorie is the amount of heat energy needed
to raise the temperature of 1 gram of water
through 1oC.
• A Kilocalorie (kCal)is 1000 calories.
• Joule = 4.2 kCal.
• A Watt is equivalent to the use of one joule
per second.
• Power is the work performed per unit of time
and is measured in watts.
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Work
• Work is defined as force x distance.
• It can be measured in calories and joules.
Food
• Food is chemical energy.
• It is converted into movement (kinetic
energy).
• Or is stored as potential energy.
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Energy release in the body
• Energy release in the body is complicated.
• There is only one usable form of energy in the
body – adenosine triphosphate (ATP).
• All food we eat has to be converted into ATP.
• ATP is a high energy phosphate compound made
up of adenosine and 3 phosphates.
• The bonds that hold the compound together are a
source of a lot of potential energy.
• ATP = adenosine-phosphate-phosphate-phosphate
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• When a compound is broken down( the bonds
between the molecules are broken) the
energy is released.
• ATP is broken down to adenosine diphosphate
(ADP) and free phosphate, releasing the
stored energy.
• ATP → ADP + P + Energy
• The energy released from the breakdown of
ATP to ADP and P is converted to kinetic and
heat energy.
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Methods of ATP production
• Once ATP has been broken down to release energy it
has to be put back.
• There are three ways that this is achieved in the human
body:
• 1 The phosphocreatine system (ATP/PC) or alactic
system.
• 2 The lactic acid system or anaerobic glycolysis.
• 3 The aerobic system.
• Each method is good at supplying energy for particular
energy demands and duration.
• Systems 1 and 2 are anaerobic they take place without
oxygen
• System 3 is aerobic: it requires oxygen to work.
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The ATP Molecule
Adenosine Triphosphate (ATP)
Adenosine
P
P
P
The breakdown of ATP:
P
Adenosine
P
Energy
ATP = ADP + energy for biological work + P
(ADP = Adenosine Diphosphate)
Energy for cellular function
P
ATP Production by Phosphocreatine or
Alactic System
• Phosphocreatine is a high- energy phosphate
compound.
• It is found in the sarcoplasm of the muscle.
• Potential energy is stored in the bonds of the
compound.
Phosphocreatine → P+ Creatine + Energy
creatine kinase
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• Creatine kinase is activated when the level of
ADP in the muscle cell increases.
• It is when the stores of ATP start to diminish.
• The energy released by the breakdown of PC is
used to convert ADP to ATP.
• Energy has to be liberated by the breakdown
of PC before ATP can be formed.
• Stores of PC in the muscles are enough to
sustain all out effort for about ten seconds.
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• This is the only system capable of producing
ATP quickly.
• During activities that demand large amounts
of energy over a short period of time
• As PC is stored in the muscle it is readily
accessible as an energy source.
• Energy for ATP can be obtained extremely
quickly.
• No fatiguing by products are released.
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ATP production by the lactic acid
system or Glycolysis
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•
•
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Also anaerobic taking place in the sarcoplasm.
The energy needed comes from the food we eat.
It involves the partial breakdown of glucose.
Breakdown of PC does not rely on the availability
of oxygen.
• It is much more complex than Phosphocreatine.
• It therefore stores more energy.
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The Glycolytic System
•Involves the breakdown (lysis) of glucose by glycolytic
enzymes.
•Glucose comes from the digestion of carbs & breakdown of
glycogen during glycogenolysis.
•Glycogen is made from glucose during glycogenisis.
•Glycolysis produces pyruvic acid which is then converted to
lactic acid in the absence of oxygen.
• Glucose is broken down anaerobically (in
absence of oxygen).
• Because there is no O2 lactic acid is formed.
• Breakdown of bonds in glucose release
energy.
• The energy is used to synthesise ATP.
• The lactic acid system takes longer to produce
energy than the ATP/PC system.
• It supplies energy for high intensity activities
for about a minute.
• The 400m is a good example.
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Outline of Lactic Acid System (anaerobi
glycolysis)
Production of energy for resynthesis of ATP
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ADENOSINE TRIPHOSPHATE (ATP)
Formed in the breaking down of
This causes FATIGUE in the
muscles.
& H+
If there is insufficient
oxygen LACTIC ACID
accumulates
GLUCOSE
This in turn is broken
down by a chemical
reaction to give
PYRUVIC ACID
LACTIC ACID SYSTEM
Glycogen made from glucose from digested food present in all
cells of the body – muscles, liver
When glycogen breaks down it releases pyruvic acid and
energy.
This energy is used to re-build ATP from ADP and P
This system is anaerobic – no O2
Pyruvic acid is easily removed when O2 is available
No O2 = Pyruvic acid is converted into lactic acid
Muscles fail to contract fully - fatigue
•
The lactic acid builds up due to the
shortage of O2 = oxygen debt
needs to be paid back once exercise
has finished.
•
Takes about 20 – 60 mins to remove
accumulated lactic acid after maximal
exercise
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Lactic acid build-up makes muscles feel
tired & painful exercising
anaerobically can only be done for short
periods of time.
Accumulation of Lactic Acid
Lactic acid affects muscular contraction by:
1. Inhibiting the secretion of calcium that enables the
coupling of actin and myosin protein filaments = protein
filaments cant attach to each other. The sliding of the muscle
protein filaments = not possible.
2. Inhibiting the action of the glycolytic enzymes = glucose not
being broken down. Glucose is the food fuel for both
anaerobic and aerobic glycolysis.
Fatigue
• When glycogen is broken down anaerobically
lactic acid is produced.
• If lactic acid accumulates it lowers the pH (H+).
• pH affects action of phosphofructokinase.
• It also affects lipoprotein kinase that breaks
down fat.
• The body’s ability to synthesise ATP is
temporarily reduced causing fatigue.
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Production of ATP using the Aerobic System
• Needs oxygen.
• At the onset of exercise there isn’t enough O2
to break down food fuels.
• So the 2 anaerobic systems are used.
• As heart rate and rate of ventilation increase
more oxygen gets to the working muscles.
• Within 1-2 minutes the muscles are being
supplied with enough O2 to allow effective
aerobic respiration.
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Stage 1:Aerobic glycolysis
• Aerobic glcolysis is the same as anaerobic
glycolysis.
• Glucose is broken down to pyruvic acid.
• As O2 is now present the reaction can proceed
further than in anaerobic glycolysis.
• Lactic acid is not produced.
• Two molecules of ATP are synthesised at this
stage.
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Stage 2: The TCA/Citric acid/Krebs’
Cycle
• The pyruvic acid produced in the 1st stage
diffuses into the matrix of the mitochondria.
• A complex cyclical series of reactions now occurs.
• During the cycle three important things happen:
1.carbon dioxide is formed.
2.oxidation takes place-hydrogen is removed from
the compound.
3.Sufficient energy is released to synthesis 2
molecules of ATP.
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The Kreb’s Cycle.
• The pyruvic acid is taken by the enzyme acetyl
CoA into the Kreb’s cycle in the mitochondria
Glycogen
2 ATP
Lactic acid
*Sarcoplasm*
Pyruvic acid
Acetyl CoA
*Mitochondria*
2CO2
Removed
via lungs
Kreb’s cycle
2 ATP
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Stage 3:The Electron transport
chain/electron transport system
• The H2 atoms removed in stage 2 are transported by
coenzymes to the inner membrane of the
mitochondria.
• The electrons are passed along by electron carries
combining with O2 and H2 ions to form water.
• Energy is released which combines ADP with
phosphate to form ATP.
• The energy yield from the electron transport chain
forms 34 molecules of ATP.
• The total yield of ATP from aerobic respiration is
therefore 38 molecules of ATP.
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• The aerobic system of synthesising ATP is the
most efficient.
• The byproducts (CO2 and H2O) are easily
expelled from the body.
• However the reactions involved in this system
depend on the availability of O2.
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Electron transport chain
• Involves water (perspiration), heat and large
amounts of ATP being released.
• Aerobic system breaks down carbs rather than fats
to release energy (fats produce more ATP than carbs
but require more O2 to produce equivalent amount
of ATP.)
• Aerobic system is fatigue resistant = primary source
of ATP for endurance activities.
• Aerobic production of ATP happens in the
mitochondria.
The ETC.
Krebs cycle
Mitochondria
matrix.
O2
H2O
Hydrogen
ETC
Mitochondria
cristae
34ATP
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Characteristics of the 3 Energy Systems
Energy
System
Aerobic/
Anaerobic
Fuel/
Energy
Source
By-product
Exercise
intensity
Duration
Sporting
Examples
NOTES
ATP/ PC
Anaerobic
ATP/ PC
Creatine
High
(Flat Out)
10 – 15
Seconds
Sprinting,
athletic field
events, weightlifting.
Small muscular
stores of ATP and PC
are exhausted quickly
leading to a rapid
decline in immediate
energy.
Lactic
Acid
Anaerobic
Glycogen
Glucose
Pyruvic Acid/
Lactic Acid
High
Intensity
Up to 3
minutes
400m
800m
Racket sports.
Lactic acid is a byproduct and can
cause rapid fatigue.
Aerobic
Aerobic
Fat/
glucose
mixture
Water/ CO2
Low
3 minutes
onwards
Long distance
running/
cycling.
This system is
limited by
availability of O2