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Exam 1 Book Notes PET3380CChapter 5• the capacity to extract energy from the food macronutrients and continually transfer it at a high rate to the contractile elements of skeletal muscle determines one' capacity for athletics• specific energy transferring capacities that demand all out explosive power for brief durations determine success in other sports• all forms of biologic work require power generated from the direct transfer of chemical energyEnergy – The Capacity for Work• unlike the physical properties of matter, you can't define energy in concrete terms• energy reflects a dynamic state related to change, thus energy emerges only when change occurs◦ as work increases, so does energy transfer and change• Newtonian (mechanical) perspective says that work is the product of a given force acting through a given distance◦ cells accomplish more chemical and electrical work than mechanical• bioenergetics - refers to the flow and exchange of energy within a living room• first law of thermodynamics - the idea that energy cannot be created or destroyed but transforms from one form to another without being depleted• conservation of energy principl e - it states that the total amount of energy in an isolated system remains constant over time. The total energy is said to be conserved over time. For an isolated system, this law means that energy is localized and can change its location within the system, and that it can change form within the systemPotential and Kinetic Energy• potential and kinetic energy constitute the total energy of a system• releasing potential energy transforms it into kinetic energy of motion• in some cases, bound energy in one substance directly transfers to other substances to increase their potential energy• biosynthesis - when specific building block atoms of carbon, hydrogen, oxygen and nitrogen become activated and join other atoms and molecules to synthesize important biologic compounds and tissuesEnergy-Releasing and Energy-Conserving Processes• exergonic - any physical or chemical process that releases energy to its surroundings◦ represent “downhill” processes because of a decline in free energy (G)• in a cell, pressure and volume remain stable (G = H – TS)◦ G = free energy ◦ H = enthalpy◦ S = energy unavailable because of randomness◦ T = absolute temperature (degrees in Celsius + 273)• endergonic - chemical or physical processes that store or absorb energy ◦ represent “uphill” processes and proceed with an increase in free energy for biologic work• sometimes exergonic and endergonic reactions couple to transfer energy ◦ conserves a large portion of usable chemical energy with the macronutrients• enzyme regulated transfer systems harness or conserve a portion of this chemical energy in new compounds for use in biologic work• the transfer of potential energy in spontaneous process always proceeds in a direction that decreases the capacity to perform work• second law of thermodynamics - when potential energy slowly degrades to kinetic energy ofExam 1 Book Notes PET3380Cmotion, giving rise to a lower capacity for workInterconversions of Energy • the total energy in an isolated system remains constant; a decrease in one form of energy matches an equivalent increase in another form• the net flow of energy in the biologic world moves toward entropy, ultimately producing a loss of potential energy Forms of Energy • there are 6 forms:◦ chemical◦ mechanical◦ heat◦ light◦ electrical◦ nuclearExamples of Energy Conversion• photosynthesis - nuclear fusion release part of the potential energy stored in the nucleus of the hydrogen atom; in the form of gamma radiation, then converts to radiant energy. The pigment in chlorophyll absorbs radiant energy to synthesize glucose from carbon dioxide and water, while oxygen is released into the environment• respiration - the opposite of photosynthesisBiologic Work in Humans• biologic work takes one of three forms:◦ mechanical work of muscle contraction◦ chemical work that synthesizes cellular molecules◦ transport work that concentrates substances in the intracellular and extracellular fluidsMechanical Work• generated by muscle contraction and subsequent movement• the molecular motors in a muscle fiber's protein filaments directly convert chemical energy into mechanical energy Chemical Work• continuous synthesis of cellular components takes place as other components break downTransport Work• diffusion - materials moving from an area of high concentration to an area of low concentration• active transport - the energy requiring process of moving materials from a low concentration to one with a higher concentration◦ secretion and absorption in the kidney tubules rely on this mechanism, as does neural tissue▪ these “quiet” forms of work require a continual expenditure of stored chemical energy Factors That Affect the Rate of Bioenergetics• the upper limits of exercise intensity ultimately depend on the rate that cells extract, conserve, and transfer chemical energy in food nutrients to the contractile filaments of skeletal muscle• enzymes and coenzymes greatly alter the rate of energy release during chemical reactionsWhat is in a Name?• There are 6 classifications of enzymes:◦ oxidoreductases : catalyze oxidation-reduction where the substrate oxidized is regarded as hydrogen or electron donorExam 1 Book Notes PET3380C◦ transferases : catalyze the transfer of a group from one compound to another◦ hydrolases : catalyze reactions that add water◦ lyases : catalyze reactions that cleave C-C, C-O, C-N and other bonds by other means than hydrolysis or oxidation. They differ from other enzymes in that two substrates are involved in one reaction direction, but only one in the other direction◦ isomerases : catalyze reactions that rearrange molecular structure and include isomerases and epimerases. These enzymes catalyze changes within one molecule◦ ligases : catalyze bond formation between two substrate molecules with concomitant hydrolysis of the diphosphate bond in ATPEnergy as Biologic Catalysts• enzymes - highly specific and large protein catalysts that accelerate the forward and reverse rules of chemical reactions without being consumed or changed in the reaction• W = F x D◦ w = work, F = force, D = distance• during all out exercise, enzyme activity


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FSU PET 3380C - Exam 1 Book Notes

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