skeletal muscle physiology Flashcards
what is true of the neuromuscular junction of skeletal muscle
a. nicotine Ach is realsed
b. the motor end plate serves as the post synaptic density
c. the end plate potential can only be excited
d. all of the above
d
what is not true of the excitation of a skeletal muscle contraction?
a. EPP is depolarized by Na+ rushing into the cell
b. the DEP receptor is electrically activated and allows Ca to exit the cell
c. DHP is mechanical and electrically connected
d. Ca is stored in the sarcoplasmic reticulum
d
when DHP is activated what occurs (in order)
a. mechanically activated ryanodine is released
b. tropinin changes shape moves tropomyosin off of actin binding site
c. Ca is released from sarcoplasmic reticulum
d. Na depolarization switches DHP receptor on
d, a, c, b
at an end plate potential there will always be an ___ ___
action potential
______ takes a phosphate off of ATP and hooks it onto myosin head
ATPase
what is true of cross bridge cycling?
a. charged myosin head attaches to actin binding site to begin power stroke
b. myosin then gets pulled closer to the midline and sarcomere shortens
c. The cross bridge cycling will continue with or without ATP
d. tropomyosin must be shifted over actin to continue cross bridge cycling
a
relaxation of the somatic neuron stimulation involves stopping release and activation of what two things
DHP and ryodine
______ removes Ca from cytoplasm and puts it back in storage
Ca ATPase
which of these doesn’t play a direct role in relaxation
1. Ca ATPase
2. troponin & tropmyosin
3. elastic & connective tissue
4. Sodium
Sodium
a myofiber twitch is
1 alpha motor neuron AP, 1 myofibril AP
excitation to beginning of a contraction
latent period
occurs when you don’t have complete relaxation between twitches
summation
complete or fused tetanus means there is no relaxation of myofibrils; true or false?
true
small motor units have what characteristics
small alpha motor neuron and small diameter myofibers
larger motor units will be recruited first to execute a movement; true or false
false
what is it called when you activated motor units are alternated to reduce fatigue
asynchronous recruitment
which of these is true of phosphocreatine
a. creatine phosphate makes ATP
b. at rest: phosphocreatine + ADP –> creatine + ATP
c. is short term lasts 10-15 seconds
d. all of the above
c
what happens to creatine phosphate after it is used
released into blood stream (2 isozymes can be used to detect heart attack based off what type of creatine is in blood.)
what are two ways to make ATP
anaerobic respiration and aerobic respiration
what is true of anaerobic respiration?
a. it is faster than aerobic but has a short duration of less than a minute
b. is limited to using glycogen and glucagon sources for energy
c. has an ATP yeild of 2
d. all of the above
d
what is not true of aerobic respiration
a. glucose breaks all the way down to CO2 which is then exhaled
b. yeild 30-32 ATP
c. is for long endurance exercises
d. glucagon anf glycogen provide most of the ATP and energy
d.
fatty acids give the most energy
fatigue that is characterized by no innervation of lower motor neuron or issues with mechanics of cross bridge cycling
peripheral fatigue
with continued myofiber use what is lost to the interstitial fluid which effects the ability to repolarize (results in fatigue)
K+
which of these are factors of fatigue?
a. lack of calcium to bind to troponin
b. high levels of ADP + Pi in cytoplasm may inhibit release of ADP from myosin heads
c. equilibrium within cell and cytoplasm
d. dehydration & low blood sugar
e. all of the above
e
what removes lactic acid and sends it to the liver to be filtered and released to the blood stream to be coverted into glucose
cori cycle
what is not true of fast twitch fibers
a. high ATPase fibers
b. crossbridge cycling 2-3x faster than slow twitch
c. low CaATPase activity
d. all of the above
c
what fibers have high myoglobin, blood supply and mitochondria (small diameter)
oxidative fibers
do anaerobic respiration have large diameter, less myoglobin and mitochondria
glycolytic fibers
which is not a characteristic of a slow twitch or slow oxidative fiber (type I)
a. slow contraction
b. fatigue quickly
c. small in diameter
d. can’t build much force
b
which is a characteristic of a fast twitch or fast oxidative glycolytic fiber (type IIa ) ?
a. fast contraction
b. resist fatigue longest
c. built a lot of force
d. smallest in diameter
a
fastest contraction, fatigue quickly, and build a lot of force; these are characteristics of what muscle fiber?
fast twitch glycolytic (type 2b)
what disease kills alpha motor neuron and results in flaccid paralysis
polio
disease characterized by lack of dystophin and degradation of muscle cells
muscular dystrophy
autoimmune disease, antagonistic antibodies mimic Ach; results in decreased sensitivity to Ach
myasthenia gravis
