PET3380C Exam 1 Book Notes Chapter 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 energy Energy 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 bioenergetics refers to the flow and exchange of energy within a living room through a given distance cells accomplish more chemical and electrical work than mechanical first law of thermodynamics transforms from one form to another without being depleted conservation of energy principl 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 system the idea that energy cannot be created or destroyed but e it states that the total amount of energy in an isolated system Potential 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 become activated and join other atoms and molecules to synthesize important biologic compounds and tissues when specific building block atoms of carbon hydrogen oxygen and nitrogen biosynthesis Energy Releasing and Energy Conserving Processes any physical or chemical process that releases energy to its surroundings exergonic 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 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 of chemical or physical processes that store or absorb energy Exam 1 Book Notes PET3380C motion giving rise to a lower capacity for work Interconversions 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 nuclear Examples 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 Biologic Work in Humans the opposite of photosynthesis biologic work takes one of three forms mechanical work chemical work transport work of muscle contraction that synthesizes cellular molecules that concentrates substances in the intracellular and extracellular fluids Mechanical Work Chemical 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 continuous synthesis of cellular components takes place as other components break down materials moving from an area of high concentration to an area of low concentration Transport Work diffusion active transport 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 the energy requiring process of moving materials from a low concentration to 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 reactions What is in a Name There are 6 classifications of enzymes oxidoreductases hydrogen or electron donor catalyze oxidation reduction where the substrate oxidized is regarded as Exam 1 Book Notes PET3380C catalyze reactions that add water catalyze the transfer of a group from one compound to another transferases hydrolases 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 and epimerases These enzymes catalyze changes within one molecule hydrolysis of the diphosphate bond in ATP catalyze reactions that rearrange molecular structure and include isomerases catalyze bond formation between two substrate molecules with concomitant isomerases ligases Energy as Biologic Catalysts W F x D highly specific and large protein catalysts that accelerate the forward and reverse enzymes rules of chemical reactions without being consumed or changed in the reaction w work F force D distance during all out exercise enzyme activity increases tremendously as energy demands rise about 100 times above the resting level many enzymes operate outside the cell ie bloodstream digestive mixture intestinal fluids Reaction Rates proteolytic action the catabolic process of breaking down complex proteins into simple amino enzymes do not all operate at the same rate some operate slowly others
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