There are three major factors that increase the

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There are three major factors that increase the number of cross-bridges thatform in a muscle fiber:(1) Frequency of stimulation(2) Muscle fiber diameter(3) Muscle fiber length at the time of contraction
FORCE OF CONTRACTION IN WHOLE MUSCLESForce generation is much more dependent on the total number of muscle fiberscontracting together.1.Recruitment2.The Size Principle3.Type of isotonic and isometric contractions-Concentric Contraction-Eccentric Contraction
MUSCLE FIBER TYPES
SKELETAL MUSCLE FIBER TYPES
SLOW TWITCH MUSCLE FIBERS (TYPE I)contract more slowly, more fatigue- resistantrespond relatively slowly to nervous stimulationbreak down ATP slowly because their myosin heads have a slow form of myosinATPaseAerobic respiration is the primary source for ATP synthesisCapacity to perform aerobic respiration is enhanced by a plentiful blood supplyand the presence of numerous mitochondriacontain large amounts of myoglobin
FAST TWITCH MUSCLE FIBERS (TYPE II)respond rapidly to nervous stimulationTheir myosin heads have a fast form of the enzyme, myosin ATPasea less-well-developed blood supplyhave very little myoglobin and fewer and smaller mitochondriahave large deposits of glycogen and are well adapted to perform anaerobicrespiration (not adapted for supplying a large amount of ATP for a prolongedperiod)muscle fibers tend to contract rapidly for a shorter time and to fatigue relativelyquicklycome in two forms: type IIa, or fast-twitch oxidative glycolytic (FOG) musclefibers, and type IIb, or fast-twitch glycolytic (FG) muscle fibers
HEAT PRODUCTIONHeat is a by-product of chemical reactions in muscles.The rate of metabolism in skeletal muscle differs before, during, and after exerciseNormal body temperature results primarily from this heatShivering produces heat to maintain body temperature
EFFECTS OF EXERCISEMuscles increase (hypertrophy) or decrease (atrophy) in size because of a change inthe size of muscle fibers.Anaerobic exercise develops type IIb muscle fibers.Aerobic exercise develops type I muscle fibers and changes type IIb muscle fibersinto type IIa fast-twitch muscle fibers.
ENERGY SOURCES FORTHE MUSCLE
ENERGY SOURCES FOR THE MUSCLESkeletal muscle fibers have three major ATP-dependent enzymes:(1) the myosin head(2)the Na+/K+ pump to maintain the resting membrane potential(3)the Ca2+ reuptake pump in the sarcoplasmic reticulum.Skeletal muscle fibers produce ATP through four processes:1. Conversion of two ADP to one ATP and one adenosine monophosphate (AMP) bythe enzyme, adenylate kinase2. Transfer of a phosphate from a molecule called creatine phosphate by the enzymecreatine kinase from ADP to form ATP3. Anaerobic production of ATP during intensive short-term exercise4. Aerobic production of ATP during most exercise and normal conditions
ANAEROBIC RESPIRATIONdoes not require O2 and involves the breakdown of glucose to produce ATP andlactate

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Term
Summer
Professor
Pfofessor talusan
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