Muscle Physiology Flashcards
isotonic
muscle contractions with movement
-goes up and comes straight down on graph
what determines time of twitch?
time that calcium is present in the cytosol
time for detachment of myosin from actin so cycle can repeat
heavy load
longer latent period
lower velocity of shortening
distance shortened is less
duration of twitch is shorter
when is tension created in a muscle?
when the myosin head is attached to the actin
what happens in an eccentric contraction?
tension is present, but muscle lengthening is happening
when will isometric turn into eccentric?
when load exceed’s muscle’s ability to cause movement
what are factors that influence muscle movement?
how fast ATP is able to hydrolyze
frequency-tension relationship
twitch lasts longer than AP (action potential)
-not having to do with intensity
summation
keep adding (stimulating) the muscle, causes Ca flooding and maintains muscle contraction
tetanus
normal muscle physiology, a maintained contraction in response to repetitive APs
unfused tetanus
low stimulus frequency (low firing rate)
-fatigue will set in layer so many muscles use this
fused tetanus
high stimulus frequency (high firing rate)
-3-5 times more tension than isometric twitch
length-tension relationship
ideal length at which muscle can generate the most tension
in resting state of muscle, the optimal length is the same as the
relaxed muscle length
what does titin attach to?
thick filament
what does titin do?
passive elastin tension of muscle
what are the 3 ways that ATP is produced for muscles?
creatine phosphate
oxidative phosphorylation in mitochondria
glycolytic pathway
creatine phosphate
protein in muscle fiber, gives up a phosphorus to make ATP
made in liver, kidney and pancreas
creatine kinase
enzyme used to phosphorylate ADP using creatine phosphate
cardiac enzymes
CK and troponin
elevated numbers indicates MI
creatine
well controlled studies indicate that it is useful for muscle health
what are the characteristics of muscle fatigue?
decreased shortened velocity
slower rate of relaxation
high-frequency fatigue
muscles fatigue rapidly, but recover rapidly
low-frequency fatigue
develops more slowly with low intensity, long duration, requires longer to recover
what do people thing fatigue is for (long term)?
a protective mechanism
what happens during fatigue in short term?
conduction failure
lactic acid buildup
inhibition of cross-bridge cycling
conduction failure
muscle AP don’t get down into T-Tubule
results from buildup of potassium in the T-tubules during repolarization
lactic acid buildup
elevated H+ buildup which alters muscle proteins and affects calcium ATPase pump
inhibition of cross-bridge cycling
delays detachment of myosin from actin
impaired relaxation
long duration exercise
depletion of substrates is probably the most important
fast fibers (type II)
high ATPase activity on myosin
rate of cross bridge is 4x faster
slow fibers (type I)
lower ATPase activity on myosin
slower contraction
-stability muscles
oxidative fibers (red fibers)
oxidative phosphorylation many mitochondria many blood vessels high concentration of myoglobin smaller diameter
glycolytic fibers (white fibers)
few mitochondria high concentration of glycolytic enzymes few blood vessels little myoglobin larger diameter fatigue rapidly
what are the three types of muscle fibers?
slow-oxidative (resistant to fatigue)
fast-oxidation or fast oxidative-glycolytic
fast-glycolytic (fatigue rapidly)
how many different types of muscle fiber are contained in one motor unit?
1 (all the same type of fiber, but have multiple motor units)
what is the sequence response of motor units?
- slow-ox
- fast-ox
- fast-glyc
(calling one each one makes the response more forceful)
fine movement will have what kind of motor unit?
1 motor neuron and 13 muscle fibers
gross movement will have what kind of motor unit?
1 motor neuron to 1000 muscle fibers
