muscular system [contractions pt 2] - unit 4 Flashcards
two types of contractions
isometric and isotonic contraction.
type of contraction. when a muscle contracts it generates force but doesn’t change in length. the myosin heads are pulling on the thin filaments
isometric contraction
type of contraction. muscle contracts + generates force and changes in length.
isotonic contraction
two types of isotonic contractions
concentric and eccentric contraction
type of isotonic contraction. muscle shortens during contraction. the myosin heads pull and move the thin filaments. (z-discs are pulled together)
concentric contraction
type of isotonic contraction. muscle lengthens during contraction. the myosin heads pull on thin filaments while the filaments go in an opposite direction.
eccentric contraction
name for a motor neuron (several hundred per skeletal muscle)
motor unit
muscles with ____ motor units have a setup for more precise movements
more
muslces with ___ motor units have a setup for imprecise movements
less
quick weak skeletal muscle contractions that arise from a single electrical stimulant to a skeletal muscle or motor unit.
muscle twitch
increase contraction strength due to an increased frequency of electrical stimulation to a skeletal muscle. (tetanic contraction / tetanus)
wave summation
two types of wave summation
unfused and fused tetanus
type of wave summation. moderate frequency of stimulation. there are brief periods of partial relaxation prior to subsequent electrical stimulation (erratic twitches)
unfused tetanus
type of wave summation. high frequency of stimulation. contractions increase in contraction force. (continuous release of Ca2+ from SR into myofibrils) (big flexion)
fused tetanus
an increase of contraction force due to the number of motor units recruited to a skeletal muscle. (NOTE: inc of motor units = inc of contraction force)
spatial summation
how skeletal muscles generate ATP
muscle metabolism
chemical that sustains muscle contractions
ATP
myosin heads bind to ATP and release from thin filaments then breakdown to ADP+P and use energy to recharge the heads in order to ____
sustain muscle contractions
typical skeletal muscle cells only have enough stored ATP to sustain about ___ seconds of continuous contraction
six
the first metabolic system. it regenerates ATP to sustain contraction/exercise.
creatine phosphate system
a small protein molecule with a phosphate attached and reacts with ADP to form new ATP
creatine phosphate
typical skeletal muscle cells have enough creatine phosphate stored to generate about ___ seconds worth of ATP for sustained contraction/exercise.
ten
metabolic process that regenerates ATP via glucose breakdown and produces pyruvic acid
glycolysis
a process of 10 reactions into smaller carbs
glucose breakdown
(glycolysis) pyruvic acid without O2. diffuses out of cell enters bloodstream, taken by liver cells, converted to glucose glucose.
lactic acid
(glycolysis) pyruvic acid with O2. in mitochondria, breakdown material to generate ATP
aerobic respiration
skeletal muscle is unable to sustain maximal contraction strength
muscle fatigue
4 causes of muscle fatigue
Lack of ATP, lactic acid buildup, phosphate buildup, ionic imbalances
cause of muscle fatigue. required for myosin heads to detach from thin filaments and recharge.
lack of ATP
cause of muscle fatigue. lactic acid diffuses into myofibrils and interferes with myosin heads binding to thin filaments
lactic acid buildup
cause of muscle fatigue. when ATP is broken down into ADP+P. P interferes with Ca2+ channels in SR and blocks Ca2+ release
phosphate buildup
cause of muscle fatigue. concentration of Na+ and K+ ions go out of whack in body and skeletal muscle cells when excessive sweating.
ionic imbalances
skeletal muscle types
slow oxidative cells/fibers, fast glycolytic cells/fibers, fast oxidative glycolytic cells/fibers
type of skeletal muscle. have myosin that breaks down ATP slowly, most efficient at generating ATP via aerobic respiration. has high levels of mitochondria/myoglobin. “Slow” twitch fibers.
slow oxidative cells/fibers
type of skeletal muscle. has myosin that breaks down ATP quickly, generates ATP efficiently via glycolysis, has low levels of mitochondria/myoglobin. “Fast twitch fibers”
fast glycolytic cells/fibers
type of skeletal muscle. moderate levels of mitochondria/myoglobin, efficient at glycolysis and aerobic respiration. “Moderate twitch”
fast oxidative glycolytic cells/fibers
steroids that stimulate muscle cells to generate more myofibrils
anabolic steroids
proportion of each skeletal muscle cell type in a given muscle is determined
genetically/via exercise
two types of exercise training
endurance, weight
type of training. stimulates cells to increase production of myoglobin/mitochondria. cells become more efficient at aerobic respiration. converts FG to FOG cells
endurance training
type of training. microscopic tears in muscle cells then they repair+stimulate to generate more contractile proteins/myofibrils. convets FOG to FG cells
weight training
