Structure of Muscle Flashcards
unit 2
what are the 3 types of muscle
smooth, cardiac, and skeletal
is smooth m. striated or nonstriated
nonstriated
is smooth m autonomic or somatic NS
autonomic NS
is cardiac m. striated or nonstriated
striated
is cardiac m. autonomic or somatic NS
autonomic NS
is skeletal m. striated or nonstriated
striated
is skeletal m. autonomic or somatic NS
somatic NS
what muslce types are multinucleated vs mononucleated
cardiac and skeletal m. are multinucleated. whereas smooth muscle is mononucleated
what is the contractile unit
sarcomere
a bunch of sarcomeres make up what
myofibril
a bunch of myofibrils make up what
muscle fiber
a bunch of muscle fibers make up what
muslce fascicle
a bunch of muslce fascicles make up what
muscle belly
what CT layer surrounds muscle fiber
endomysium
what CT layer surround muscle fascicle
perimysium
what CT layer surrounds muscle belly
epimysium
what are the 3 types of CT tissue layers
epimysium, perimysium, endomysium
what is the thin vs thick filaments
thin is actin
thick is myosin
what does the h zone only have
thick / myosin
what does the a band have
overlapping actin and myosin
where is an Ap generated, and how does it get to the NMJ
AP is generated in the motor corex of the brain and then moves down the pyramidal tract , then goes to the spinal cord and synapse at the ventral horm of the spine. 85% crosses over to the NMJ
first step of excitation contraction coupling at the Nuromuscular junction
Ach is released at the synapse and binds to Ach receptors at the motor end plate
what happens after ACh binds to receptors at motor end plate
an AP is made and that Ap travels along the T-tubules.
what happens after the AP travels along Tubules
calcium is released into the sarcoplasm of the cell to then bind to troponin
what happens after Calcium binds to troponin on actin
the active sites for myosin are opened for myosin to bind to. the myosin head then pulls the actin
what happens in the sliding filament theory
i band
h zone
a band
i band shortens
h zone shortens
a ban stays constant
what is a power stroke going to be contracting
muscle
what are the different muslce fiber types
type 1 and type 2
type 2a, 2x, and 2b
which fiber is slow vs fast twitch
type 1 is slow
type 2 if fast
steps of power stroke (roughly amber) ik you know this
- myosin head forms a cross bridge at a 45 degree angle,
- then atp binds to myosin so it releases from actin.
- ATPase breaks down ATP to get free energy.
- then the myosin head swivels inward to a 90 degree angle .
- myosin releases Pi to initiate power stroke and pulls actin toward the center.
- returns to ready start of step 1
how can a muslce relax?
calcium release channels in SR close and ATP is used to restore low level of Ca ions in sarcoplasm.
troponin and tropomyosin go back to blocking actin active sites. the muscle can then relax
order of peak power in turns of muscle fiber types
3 types
Type 2X > type 2A > Type 1
all muscle fibers reach peak power at what % of what
20 % peak force
Wich type of fiber is fatigue resistant
type 1
which type of fiber is explosive in short movements
type 2
Fiber type determinants … 3 of them
genetic factors
training factors
aging
how do genetics play a role in fiber type
determines which motor neurons innervate fibers and fibers differentiated based on alpha motor neuron.
are you born with more type 1 or 2?
how does trainng play a role in fiber type
endurance vs strengh training.
can induce a small (10%) change in fiver type.
can you shift one muslce fiber tothe other?
no, but you can enhance its abilites through the correct training
how does aging play a role in fiber type
muslces lose type 2 motor units with age more than type 1 because you don’t do as much explosive exercises
endurance athletes use which fiber type
1 predominates
sprinters use which fiber type
2 predominates
is fiber type the sole predictor of success.
no, also cardiovascular function, motivation, training habits, and muscle size
info on type 1 fibers during exercise
high aerobic endurance
can maintain exercise for prolonged periods
require Oxygen for atp
low intensity aerobic exercise too like daily activities
how do type 1 fibers produce atp
from fat and carbs
type 2 fibers in general during exercise
poor aerobic endurance, fatigue quickly, produce ATP anaerobically
type 2 a fibers during exercise info
related to force, fatigue, and intensity
more force, faster fatigue than type 1, short high intensity endurance events
type 2 x fibers during exercise info
seldom used for everyday activites, moreso short, explosive sprints
factors that affect force production? there are 8 haha
size of muscle fibers
number of motor units activated
type of motor unit
rate coding
speed of muscle action
angle of pull
initial muscle length
type of contraction
know some activites/sports that are more fast vs slow twitch fibers
more fast is sprinters,
even is like swimmers, mid distance runners
more slow is endurance runners
fiber type with most force prodution
type 2x
fiber type with most fatiguablility
type 2x
fiber type with largest size
type 2x
fiber type with most mitochondrial density
type 1
what is hennemans size principle
as recruitment electical trheshold increases, so does force production….
they always recruit in the same order, small fibers to large fibers
what is a motor neuron specific to
the muscle fiber type
what are large motor neurons/units related to
larger fiber types like type 2x
what is rate coding
the graph of what looks like for single twitch, wave summation, unfused tetanus and fused tetanus
stimulus vs firing rate of neuron
info on wave summation
before muscle can relax, a second stimuls comes in (they sum up)
info on unfused tetanus
similar to wave summation, but has multiple stimulus come before relaxing
info on fused tetanus
so many action potential so close together that we platue. can not make any force any quicker.
what happens if more ap are sent closer together
more force is produced
what is the all or none principle referring to
once a stimulus strength reaches the designated threshold, there is a full response. until threshold, there is no response at all (not partial )
can you draw the force velocity curve?
imagine starting at like 1, 5 and curving down to 1,1 on a graph
which fibers take longer to forma and contributed to force production
type 1, red fibers
what is the optimal % of resting sarcomere length
80 to 120 %
faster producing muslce fibers also produce what?
more force
2 types of muslce contraction
static (isometric )
dynamic
what are the 2 types of dynamic contractions
concentric and eccentric
static contraction (isometic) info
muscle produces force but doesnt change length, no sliding bcuz no movement. the joint angle does not change.
dynamic contraction info
muscle produces force AND changes length, the joint movement is produced.
concentric contraction info
muslce SHORTENS while producing force, sarcomere shortens and filaments slide to center (weight lifting generally)
eccentric contraction info
muscle LENGTHENS while producing force, cross bridges form but sarcomere lengthens. like lowering heavy weight.
order form most force to least force of contractions
eccentric > isometric > concentric
what is fatigue
occurs during prolonged exercise, when physical performance starts to decline.w
what are the 2 types of fatigue
central and peripheral
which intensity is associated with central and peripheral fatigue
central is low intensity
peripheral is high intensity
how is fatigue percieved
burning, soreness, decreased motivation
where does central fatigue originate
proximal to NMJ
where does peripheral faigue originate
distal to NMJ
accumulation hypothesis time and what is it
30 sec to 3 min activites
build up of metablic byproducts
what is depletion hypothesis
running out of fuel,
from prolonged exercise
no fuel source to produce ATP (phosphogen or glycoen
what are the 2 ways to combat fatigue
glycogen supercompensation “ carb loading”
and biocarbonate loading
what does glycogen supercompensation do to combat fatigue
goal is to increase muscle glycogen before competition , in combination with tapering
what does biocarbonate loading do to combat fatigue
reduces acidity in cell envrionment
favors diffusion of lactate
afferent or efferent group 3+ 4 neurons affect fatigue ?
afferent, affect peripheral fatigue
