Racing – ATP consumption
1 . ATP is the usable form of energy for muscular activity. It is stored in most cells but is most particularly
found in muscle cells. The trained athlete has the ability to use the system of ATP replenishment to supot
varying activities. You would have to calculate the ATP used here based on the information in the chart. I
don’t necessarily know the formula for calculating this, however, you can easily determine this by taking
the available amount of ATP in the muscles and subtracting the use of energy based on the chart given.
2 . A race that is 1000m would not use the same mix of energy sources. This is because a 1000 meter
sprint would require fast twitch muscles and a burst of energy. Compared to the stores of energy
required for a marathon. The 1000m race requires fast access to energy stores and as quickly as possible
otherwise the muscles wouldn’t be high performing. The opposite is required for a marathon, where you
need lots of energy over a long period of time, a 1000m sprint needs a lot of energy over a short period of
time. Thus, the difference in energy consumption is indicative of the different types of energy mix that
one would need.
3 . During a marathon, there are a variety of energy sources that the body can use to successfully
complete the race. Heavy breathing allows oxygen to enter the body which then combines with fuel to
produce energy. This “fuel” can come from three different areas (fat, protein and carbohydrates). Protein
is important and accounts for almost 5% of the body’s energy. Fat contributes almost 60% of the energy
produced at rest, however, in a marathon this is reduced to almost 15%. The bulk of this energy is taken
from the breakdown of glucose. During aerobic exercise, glucose combines with oxygen to form energy.
Glycogen is important for runners, and is stored in the liver and muscles. It is important to carbohydrate
load before a race, to replenish the glycogen levels in the muscles and liver. As the heart race furthers,
more oxygen is needed before you reach a steady state.
4 . Eating a boost of glucose just before the race would be a mistake mainly because your body should
have already loaded up on energy preserves a few days before. Eating glucose right before a marathon to
give yourself a boost would only cause excess glucose in the body which could lead to cramping. It is okay
to have a glucose intake during the race to replenish you body’s glucose levels. This would be beneficial
because your body is using so much energy to run the marathon, by having an intake of glucose, you can
replenish these energy supplies.
Felig cycle
1 . The Cori Cycle is also referred to as the lactic acid cycle. This refers to the metabolic pathway in which
lactate (produced by anaerobic glycolysis in the musculature) are actually converted and moved to the
liver where they are converted to glucose. They will then return back to the muscle and metabolize back
to lactate. This aids in the energy consumption of the muscle system of the human body. This is provided
by the breakdown of glycogen in the skeletal muscles.
1. Breakdown of glycogen (glycogenolysis) releases glucose in the form of G1P
2. G1P is converted to glucose 6-phosphate (G6P); this provides ATP to muscle cells as energy
3. When oxygen is sufficient – the ATP comes from feeding the Krebs cycle pyruvate (a byproduct of
glycogenolysis)
4. When oxygen is insufficient (during exercise) – ATP comes from anaerobic metabolism (lactic acid
fermentation)
5. Fermentation oxidizes NADH produced by the glycolysis back to NAD+ (maintaining NAD+
concentration so that additional glycolysis can occur)
6. NADH reduction allows pyruvate to become lactate
7. Lactate is taken up by the liver – initiating the second half of the Cori Cycle
8. Glyconeogensis occurs – reverses both glycolysis and fermentation by converting lactate to
pyruvate to glucose
9. This glucose then is added back to the blood where it is sent to the muscles again
Overall, glycolysis produces 2 ATP (in the muscles) and costs 6ATP (in the liver). Thus the net consumption
of 4ATP means that the cycle cannot be maintained for long periods of time, due to the lack of energy
available at that consumption rate. The cycle is extremely important in the prevention of lactic acid
production which can eventually lead to acidic build up in the muscles. The cycle produces ATP during
muscle strain, which is vital during exercise and the ability to sustain exercise longer.
2 . The alanine cycle is similar to that of the Cori cycle. When muscles produce lactate during the times of
oxygen depletion, they also produce alanine, which is then taken to the liver for processing. This cycle,
however, is less effective than the Cori cycle (which uses lactate as an energy by-product). A by-product
of the alanine cycle is Urea, which requires energy to remove. The new ATP produced is less than that
found in the Cori Cycle. Dissimilar to the Cori cycle, however, is the role of NADH. NADH is conserved
because lactate is not formed. This is allows for it to become oxidized via the ETC, also requiring the
presence of alanine aminotransferase (restricted to the liver/ muscle). This cycle is used only when
alanine aminotransferase is present.
1. Glycogen broken down in the muscle (G1P – G6P)
2. The glycolysis of G6P creates pyruvate
3. Pyruvate reacts with amino acids of the muscle proteins via transaminases and keto-acids to
become alanine
4. Alanine can then be transferred into the blood stream and sent to the liver
5. The alanine then reacts with NH3 (created from NH4+ and a-ketoglutarate in the liver) to turn
this into pyruvate
6. The pyruvate reacts via gluconeogenesis to create G6P which can readily be turned into glucose
7. The glucose then is sent via the blood stream back to the muscles.
3 . Comment on the respective balance sheets of both cycles cofactor NADH and indicate the fate or the
source of this co- factor if necessary.
Above is a diagram showing all the products of each cycle. Ferig (left) and Cori (right).
The Cori cycle uses a net ATP of 4. It creates 2ATP and uses 6ATP.
The Ferig cycle uses 4ATP to remove Urea via deamination because of the urea by-product.
The Ferig cycle also conserves NADH because lactate isn’t formed, whereas the Cori cycle uses NADH to
create lactate.
4 . Anaerobic metabolism is an exercise intense enough to trigger lactic acid formation. It involves
hardcore training by athletes to promote strength, speed and power. There are two types of anaerobic
energy systems: 1) high energy phosphates, ATP, and 2) anaerobic glycolysis. This is the main reason why
Felig cycle cannot be used during anaerobic metabolism because of the lack of ATP present. The body is
using the ATP at a fast rate and therefore cannot be used in the cycle at an expenditure. The body makes
glucose for energy usage, however, at the expenditure of ATP, which is not in supply during anaerobic
metabolism.
Glycogen
What are the commonalities , what differencs between liver glycogen and muscle glycogen for their
metabolisms , the regulation of these metabolisms and their metabolic roles / physiological ?
As a person ingests a meal, the digested food contains carbohydrates. This results in blood glucose levels
rising, causing the pancreas to secrete insulin. After the meal has been digested, however, insulin
secretion is reduced, and glycogen synthesis stops. This is then stored in the liver. Glycogen in the liver is
then broken down when energy is needed, by way of a conversion to glucose. Glycogen phosphorylase is
responsible for breaking down glycogen to glucose. Compared to muscle glycogen which functions
primarily as an immediate reserve of energy for muscle cells. Muscle cells will lack G6P, which is required
to pass glucose into the blood, and thus they store glycogen in the muscle cells. It is insoluble in water,
and therefore cannot pass into the blood stream and be shared with other parts of the body.
Thermogenesis
1 . Most adipose tissue depots are primarily a storage that provide a reservoir of nutrients for release
when flood supply is low. Brown adipose tissue, is highly vascularized and rich in mitochondria. This
allows the tissue to oxidize fat so rapidly that it generates head. The nervous system stimulates a
catabolic program that commences with the rapid breakdown of triacylglycerol stores in the brown
adipose tissue. The key molecule is believed to be the uncoupling of protein-1, which uncouples electron
transport in the respiratory chain from ATP production with a highly exothermic release of energy. Lipid
metabolism is the process that involves the degradation of lipids.
1. Norepinephrine induced stimulation- stimulate cAMP function – stimulate PKA – which reacts
with TG (triglyceride).
2. This activates FFA (free fatty acids) which in turn react with acyl-coA synthetase.
3. The acyl-coA enters the mitochondria, ensuing beta-oxidation of the fatty acids as well as the
citric acid cycle (CAC). FADH and NADH are produced.
4. NADH and FADH are used in the ETC ultimately through oxygen consumption, this results in the
pumping out of protons from the mitochondria and the formation of a proton-motive force that
drives the protons back into the matrix
5. The energy stored in the proton movement is released as heat
2 . Thermogenin is responsible for the enormous amounts of heat generation in brown adipose
mitochondria. This doesn’t occur in normal cells, only brown adipose tissue. This is essential for nonshivering heat generation. Non-shivering heat generation is mainly used in mammals who hibernate and
need a continuous amount of heat in their body, as well as human infants who must stay warm.
3 . Thermogenesis is the process of heat production in organisms. Upon activation, substances such as
free fatty acids remove purine inhibition of thermogenin. This uncouples protein-1. This causes an influx
of H+ ions into the matrix of the mitochondrion and bypasses the ATP synthase channel. The dissipation is
resulted in heat. Thermogenesis is subsequently stimulated alongside lopgenesis and lipolysis or glycolysis
and gluconeogenesis.
4. Thermogenin is an uncoupling protein found in the mitochondria of brown adipose tissue. It is
essentially used to generate heat by non-shivering thermogenesis. Uncoupled proteins increase the
permeability of the inner mitochondrial membrane allowing protons to be pumped through. UCP-1
mediated heat generation occurs in brown fat. This uncouples the respiratory chain, allowing for faster
oxidation with a low rate of ATP production. UCP-1 is restricted to only brown adipose tissue where it is
responsible for the large amounts of heat generation.