Biochemistry

a two-carbon molecule with Coenzyme A attached. This is the fundamental molecule that is required for oxidative metabolism (Kreb’s Cycle) in the mitochondria

a transport molecule in the mitochondrial inner membrane that exchanges ADP and ATP across the inner membrane

an enzyme that adds a phosphate to a number of enzymes in response to low energy state in the body. Consequences include glucose and fatty acid mobilization and transport

releases free fatty acids from triglycerides stored in adipose tissue

Volume of  air exchanged with the lungs are often measured under ambient conditions and the air is saturated once in the lungs

an enzyme that results in phosphorylation of ADP to form ATP. ATP (adenosine triphosphate) is the primary source of energy in the body

Lung volumes are typically presented with conversion to the volume that would exist at body temperature (37 degrees C), ambient pressure, saturated with water vapor. This represents the condition in the body, so gives an accurate reflection of air volume.

initial fast increase in oxygen uptake at the initiation of exercise. This increase in transport of oxygen across the lungs from alveolae to blood results from the very fast increase in blood flow through the pulmonary vasculature at the initiation of exercise

a fatty acid transport molecule that makes fatty acids available for metabolism

metabolic breakdown of chemical substances; for example, protein degradation resulting in muscle atrophy

this term describes the process by which creatine is phosphorylated (creatine becomes creatine phosphate) at the mitochondrial membrane by mitochondrial creatine kinase then diffuses into the myofibrils or subsarcolemmal areas where cytoplasmic creatine kinase can transfer the phosphate from creatine phosphate to ADP, forming creatine and ATP

electron acceptor in the electron transport chain, interacting with Complex I and II

first complex of the electron transfer chain of the mitochondria. Here, an electron is removed from NADH and accepted by Coenzyme Q and the energy is used to transport a H⁺ into the mitochondrial matrix

the second complex of the electron transport chain, comprised of a complex of succinate dehydrogenase typically accepts an electron from FADH2 and passes that electron to Coenzyme Q without transporting H⁺ into the matrix

the third complex of the mitochondria that participates in electron transfer chain. This complex transports a H+ into the matrix, assisting the formation of ATP

the fourth complex of the mitochondria that participates in electron transfer chain. The final electron transfer step is to Oxygen, forming water. This complex also transports a H⁺ into the matrix

follows the carbon associated with glucose released from glycogen through glycolysis to the formation of lactate which gets into the blood and taken up by the liver for gluconeogenesis

the process by which creatine is phosphorylated (creatine becomes creatine phosphate) at the mitochondrial membrane by mitochondrial creatine kinase then diffuses into the myofibrils or subsarcolemmal areas where cytoplasmic creatine kinase can transfer the phosphate from creatine phosphate to ADP, forming creatine and ATP

intensity of exercise that is associated with 50% fat and 50% carbohydrate contribution. Below this intensity, more fat than carbohydrate is used. Above this intensity, more carbohydrate than fat is used

a protein associated with the inner membrane of the mitochondria that serves to transport reducing equivalent from Complex III to complex IV of the electron transport chain

protein complex on inner mitochondrial membrane that mediates transfer of electrons into the electron transfer chain. 

an enzyme that removes hydrogen from a molecule, typically transferring that H+ to another molecule

lactate dehydrogenase

enzyme that converts pyruvate to lactate and back, present in the cytosol of myocytes (and other cells). Reaction  includes NAD+/NADH making NAD+ available for continuing glycolysis.

pyruvate dehydrogenase

converts pyruvate, a product of glycolysis to acetyl CoA, the molecule that is taken into the Citric Acid Cycle.

the process of breaking down ad absorbing food from the digestive system into the blood

maintaining a balance of energy in the body; intake of calories is equal to calorie expenditure.

 the transfer of energy between forms: in the body, this includes: chemical, potential, kinetic and heat. 

transport protein that facilitates the transfer of fatty acids across a lipid bilayer membrane

the energy cost of muscle contraction is the sum of external work accomplished and the heat released. This should be equal to the biochemical energy provided for the muscled contraction. 

An important molecule that is reduced in the Krebs Cycle and oxidized in the electron transfer chain, contributing to oxidative metabolism

also, flow, the rate of change, for example the rate of incorporation or removal of a molecule involved in a metabolic pathway

The proportion of inspired air that is oxygen.This is typically assumed to be 0.2093 when inspiring ambient air. FIO2 can be manipulated experimentally to provide hyperoxia or hypoxia.

fraction of expired air oxygen;  FEO₂

fraction expired oxygen; the fraction of the exhaled air that is oxygen. FEO2 is increased with hyperventilation and decreased by exercise and hypoventilation.

 one of a family of glucose transport molecules. GLUT 4 exists in muscle tissue and is activated by insulin and/or exercise. GLUT 4 moves glucose across the plasmalemma from outside to inside, providing glucose for metabolism and helping control blood glucose concentration.

a transport system to transfer reducing equivalents from the cytoplasm (and NADH) into the mitochondria.

 The enzyme that splits glucose-1 units from glycogen.

the release of heat from the body. Heat is lost from the body by evaporation, conduction and convection. During exercise, excess heat is produced and must be dissipated to allow persistence of life

a protein that breaks apart lipid molecules like triglycerides in response to the rise in concentration of specific hormones like cortisol and growth hormone. Hormone sensitive lipase is important for providing substrate for long term exercise. 

an enzyme that adds a phosphate to another molecule. Addition of a phosphate will typically activate or deactivate the molecule, typically an enzyme.

see S6kinase

see also: myosin light chain kinase

enzyme that converts pyruvate to lactate and back, present in the cytosol of myocytes (and other cells). Reaction  includes NAD+/NADH making NAD+ available for continuing glycolysis.

enzymatic breakdown of triglycerides to free fatty acids and glycerol

 enzyme that removes converts malonyl CoA to acetyl CoA in the process of fatty acid synthesis.

the lateral pressure that would be exerted by the blood against the vascular walls when circulation is stopped. This pressure is dependent on blood volume, vascular capacity and vascular distensibility. Values typically range from 18 to 24 mm Hg

the product of force and length. Muscle contraction results in generation of force and shortening. Energy for mechanical work comes from biochemical process or stored potential energy. The force generated and the length change when multiplied together give mechanical work. When muscle lengthening occurs, work is done on the muscle. The energy for work done on the muscle comes from external sources plus biochemical processes.

molecules and heat resulting from reactions of metabolism. An example would be CO₂ is a metabolic byproduct of the Kreb’s cycle.

 Discrete changes in the metabolic contributions of oxidative and non oxidative metabolism are recognized as thresholds. Aerobic threshold occurs during an incremental test when non aerobic metabolism results in a clear increase in blood lactate. Anaerobic threshold  is the highest intensity of exercise that can be sustained with entirely aerobic energy. Maximal oxygen uptake is also a boundary condition, above which any additional energy requirement must be met with non aerobic metabolism.

inward folded loops of inner membrane of mitochondria. The inner membrane contains the cytochromes for the electron transfer chain as well as the f-complex where ATP is generated.

 In skeletal muscle, where the mitochondrial volume is substantial, mitochondria exist not as individual organelles, but as a continuous reticulum; a membrane bound structure that occupies the space between myofibrils as well as subsarcolemmal space

 transport molecule in mitochondrial and cell membranes; transports molecules like lactate and pyruvate. 

an enzyme that catalyzes the reaction between two ADP molecules, transferring the phosphate from one of these to the other, forming AMP and ATP.

a small molecule that functions as a hydrogen donor/acceptor in oxidation reduction reactions, particularly important in glycolysis, Krebs cycle and electron transfer chain

reactions resulting in transfer of electron from one molecule to another. The one receiving the electron is reduced, the one giving the electron is oxidized.

the ratio of phosphate added to ADP creating ATP to the atomic oxygen used. Ideal oxidative metabolism yields a P:O of 3, but reality allows typically 2.5

5-carbon ring with phosphate group attached.

an enzyme that removes a phosphate from a molecule. Removal of a phosphate from a molecule is typically going to activate or deactivate the molecule, usually an enzyme. 

Using a phosphate in breaking apart a larger molecule, like glycogen.

protein that interacts with fatty acids and facilitates solubility and transport.

an important enzyme, regulated by cAMP that adds a phosphate group to specific proteins, thereby activating or inhibiting them.

Transfer of gas through the pulmonary membranes; exchange between air and blood. Of metabolic concern is oxygen and carbon dioxide.

a three-carbon molecule, end product of glycolysis with destination as acetyl CoA in mitochondria. Alternatively, pyruvate can be converted to lactate by lactate dehydrogenase

an enzyme that adds a phosphate to pyruvate dehydrogenase, activating it.

motor units are recruited in order from smallest to largest, as force or power output increases. This sequence corresponds to slow-twitch to fast-twitch. Although there are exceptions to this principle, it is a good general way to consider recruitment of motor units.

Oxygen uptake and carbon dioxide output are usually converted to a standard temperature (0 degrees centigrade or 273 degrees Kelvin) with no water vapor pressure. This allows comparisons between studies conducted under a variety of environmental conditions.

small molecules containing 3 caboxylate groups (COOH), like citric acid. 

The volume in the various parts of the vascular system: heart, pulmonary circulation, arteries, arterioles, capillaries, venules, veins

ion channel in excitable membrane that responds to voltage change in the membrane