Unit Two - Metabolism Flashcards Preview

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Flashcards in Unit Two - Metabolism Deck (49):
1

metabolism

The sum of all the chemical reactions in the body. Many of these reactions are related where the product is the substrate of another.

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catabolism

Metabolic processes that involve the breakdown of energy yielding nutrients (and other molecules). The release of free energy and electrons.

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Anabolism

Metabolic process that builds molecules the body needs. This requires energy.

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bioenergetics

study of the science of energy conversions in living organisms. Also known as thermodynamics.

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first and second laws of thermo

1. Energy cannot be created nor destroyed, but it can be changed from one form to another.
2. Energy transfer will always proceed in the direction of increased entropy.

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calorie, kcal

-A calorie is the amont of heat necessary to raise the temp. of 1 g (ml) of water 1 degree C.
-A kCal is 1000 calories. Caloric cotent on our food is usually referred to in kCals also shown with a capital C, Calorie.

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coupled reaction

Free energy from one rxn that can drive another reaction.

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enzyme

A catalytic protein that helps speed up the rate of chemcial reactions by decreasing the activation energy.

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exergonic

Reactions that release energy. Breakdown of ATP releases energy. High energy stored in the phosophate bonds. Occur spontaneously

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endergonic

Reactions that require energy. Including the synthesis of ATP. Non spontaneous reactions.

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co-enzyme

A nonprotein compond that is necessary for the functioning of an enzyme. Such as pyruvate being converted into acetyle coenzyme A (Acetyle CoA) when intercellular reactions favor aerobic catabolism of pyruvate.

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ATP, ADP, Pi

Adenosine triphosphate, ATP, is the energy required for the body to function. ATP is the fuel for muscle contraction and exercise. The high energy is stored in its phosphate bonds. When broken down, ATP yields an inorgainc phosphate (Pi) and adenosine diphosphate, ADP.

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creatine phosphate

Creatine phosphate is a pathway to generate ATP. CP is a high-energy phosphate compoud that regenerates ATP at a very high rate. CP transfers its phosphate group to ADP in order to produce ATP (and Cr). This is a pathway used at the very beginning of exercise and is anaerobic.

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creatine kinase

PCr (creatine phosphate) breakdown is regulated by creatine kinase, enzyme, activity. This is a rate-limiting enzyme. Creatine kinase, CK, is activated when SR ADP concentration increases and is inhibited by high ATP concentration. at beginning of exercise, ATP  ADP + Pi + Energy  muscular contraction
the immediate increase in [ADP] stimulates CK to trigger the breakdown of PCr to make ATP.

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anaerobic metabolism

Does not require oxygen for the chemical reaction to proceed. For example, glycolysis is anaerobic metabolism to breakdown glucose.

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glycolysis

ATP can be produced through the breakdown of glucose in glycolysis. This occurs in the cytosol of the cell (sarcoplasm of the muscle cell). This involves ten steps and two stages: the investment of energy and then the regeneration of energy. Glucose is broken down into lactate or pyruvate with the net production of 2 ATP and 2 NADH.

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lactic acid/lactate

At the end of glycolysis there are two pyruvates. If oxygen is present and depending on rate of glycolysis reaction, the pyruvate can enter into the oxidative pathway of the Kreb's cycle. However, if the exercise is anaerobic, it cannot go into oxidative pathways therefore pyruvate is reduced to lactacte. This is sometimes necessary (even when O2) is present because too much NADH will accumulate (not enough NAD+ for glycolysis to continue), but if pyruvate is reduced to lactate then NADH is oxidized to NAD+. Lactate causes muscle cramps and soreness DURING and right after exerise. As Lactate accumulates, pH decreases, thus glycolysis slows down.

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NAD-NADH

electron carrier. 2 are NAD+ molecules are reduced to NADH during glycolysis.

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FAD-FADH2

Electron carrier

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glycogen

Glycogen is a bunch of glucose linked up in a branched formation. Glycogen can be found in the muscle and liver.

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glycogenolysis

the breakdown of glycogen to glucose-6-phosphate and glycogen.

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triglyceride

Simple fats. These are stored in adipocytes and musce. Consist of 3 fatty acids attached to a glycerol molecule.

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hormone sensitive lipase

Hormone sensitive lipase breaks down adipose tissue and free fatty acid and glycerol are released (stimulated by epinephrine & growth hormone). This allows fatty acids to travel in blood to get into cell for lipid metabolism.

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fatty acid

carbon units are grouped into fatty acids - lipids

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lipolysis

Breakdown of triglycerides to glycerol and free fatty acids

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cori cycle

Lactacte from glycolysis in the muscle cell is oxidized to pyruvate and then enters the liver where pyruvate essentially undergoes reverse glycolysis and is transformed to glucose. Then the glucose can travel through bloodstream to a muscle cell to be used in glycolysis again to produce more lactate.

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Krebs cycle

Another pathway that creates energy in the form of ATP. The Krebs, or citric acid cycle, takes place in the mitochondrial matrix. Pyruvate is converted to Acetyle CoA, the major fuel for the Kreb's cycle, when intracellular conditions favor aerobic catabolism of pyruvate. The whole cycle makes ATP by removing hydrogen electrons from acetyl groups and attaching them to NAD or FAD to feed into ETC to make ATP. For every Acetyl CoA molecule, 3 NADH are formed, 1 FADH2 is formed, 1 ATP, 2 CO2. Note that ONE molecule of glucose will make TWO acetyl CoA's.

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Acetyl CoA

The major fuel for Kreb's cycle. It goes into the cycle. It is completely oxidized during the complex chemical reactions in the Kreb's Cycle.

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electron transport chain

Produces a large amount of ATP. NADH and FADH2 are carrying electrons and the electrons are passed down the chain and lose energy. Part of this energy is used to produce ATP. This is an aerobic pathway. Oxygen is the last acceptor in the electron transport chain. During this process, protons are pumped out to form electrochemical gradient and then protons go through ATP synthase which provides energy for the phosphorylation of ADP to ATP.

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oxidative phosphorylation

Oxidative phosphorylation is the process in which ATP is formed as a result of the transfer of electrons from NADH or FADH 2 to O 2 by a series of electron carriers. This process, which takes place in mitochondria, is the major source of ATP in aerobic organisms

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beta oxidation

Once fatty acid enters the cell it is converted to fatty acyl CoA by Beta oxidation. Beta oxidation removes 2-carbon fragments from fatty acyl chain. These are acetyl CoA which can enter the Kreb's cycle

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mitochondrial matrix

The mitochondrial matrix is formed by the inner memebrane of the mitochondria. This is where the Krebs cycle takes place. Also, the ETC takes place in the membrane of the mitochondrial matrix or the inner membrane.

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steady state

balance between the energy required by working muscles and the rate of oxygen and delivery for aerobic ATP production. The body maintains a balance while exercising. Heart rate, respiration, and metabolic processes are maintained at a level.

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VO2, VO2max

VO2 refers to the oxygen consumed or utilized for metabolic processes in order to create energy for exercise. VO2 max is the physiological ceiling for delivery of O2 to muscle. This is affected by genetics and training.

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RER

Respiratory exchange ratio. This can estimate the percent contribution of carbohydrates or fat to energy metabolism
during exercise. An RER of 0.7 is the lowest this ratio can go and this indicates 100% fat being used for energy production. An RER of 0.82 is an RER at rest (slightly more fat burn) and an RER of above 1.0 is possible and indicates that the individual is producing more CO2 than they are consuming O2 which indicates that he or she is hyperventilating and nearing a VO2 max - this usually occurs above 1.1 RER.

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lactate threshold

This refers to the point during an incremental exercise test (test that's getting more difficult) that blood levels of lactic acid increase exponentially. In an untrained person this usually occurs around 50-60% of his or her VO2 max. In a trained individual this takes place from 65-80% of VO2 max.

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O2 deficit

This is the difference between the amount of O2 consumed during adjustment to exercise & the amount that would have been consumed IF steady state were attained immediately. This can be illustrated graphically.

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O2 deficit

This is the difference between the amount of O2 consumed during adjustment to exercise & the amount that would have been consumed IF steady state were attained immediately. This can be illustrated graphically. A trained person has a smaller O2 deficit.

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EPOC, O2 debt

EPOC: excess post-exercise oxygen consumption. After exercise, metabolism remains elevated for several minutes and therefore excess O2 is consmed. This can also be seen graphically. Similarly to deficit, an trained individual would be able to attain steady state quicker and thus expend less O2 and have a lower O2 debt. The factors involved in EPOC include resynthesis of PC in muscle, lactate conversion to glucose, restoration of muscle and blood O2 stores, elevated body temperature, elevated HR and breathing, and elevated hormones.

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power

Mechanically speaking, power is defined as work completed over an amount of time. Higher power means more work completed or work completed more quickly. With regards to exercise, power usually is related to reps per min. Where a rep is moving a force across a distance thus work.

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work

Mechanically, force multiplied by a distance.

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mechanical efficiency

The ratio of energy input to output is referred to as efficiency. The human body is only 25-40% efficient. The rest of the energy is not usable and is released as heat. Large muscles are more efficient while small muscles are less efficient. Many engines can only perform work with 25% of the energy used.

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direct calorimetry

Is based on the theory that the rate of heat production is directly proportional to metabolic rate. This is achieved through an airtight, thermaly insulated living chamber. This would provide O2, but absorb CO2. The heat from the body increases the temperature of water surrounding unit. The heat produced can dbe used to determine energy expenditure. This is precise, but expensive af.

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indirect calorimetry

This is based on the theory that there is a direct relationship between O2 consumption and the amount of heat produced by the body. This will indirectly estimate energy metabolism by measuring O2 consumption. However, for this to work, a person must be at rest or in a steady state exercise.

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MET

this is a way to quanitfy resting O2 consumption. Where the average resting O2 consumption is 3.5 ml/kg/min.

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VO2 = ...

VEstpd (0.2093-FEO2)

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VCO2 = ...

VEstpd(FECO2)

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STPD

standard temperature pressure dry. During Vo2 calcs, we convert from atps to stpd in order to have consistent calculations.

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ATPS

ambient temperature pressure saturation. All of these have an effect on the volume of gas and thus have to be considered when calculating VO2