ch17 Flashcards
connective tissue surrounding entire muscle
epimysium
connective tissue surrounding bundles of muscle fibers (fasciculi, fascicle)
perimysium
surrounds individual muscle fibers
endomysium
storage sites for calcium and contain terminal cisternae (lateral sacs)
sarcoplasmic reticulum
inside cytoplasm and contains transverse tubules [carry electrical signal to releasle Ca]
sarcoplasm : transverse tubules
thick filaments include __: reactive sites that create crossbridges and have a rodlike tail
myosin
___ filaments are actin, tropomyosin, and troponin
thin
3 subunits of troponin is
tn-C
tn-T
tn-I
troponin subunit that contains Ca binding sites
Tn-C
troponin subunit that binds to tropomyosin
tn-T
troponin subunit that inhibits binding of actin/myosin during rest
tn-I
- neuron action potential arrives at end of motor neuron
- ach is released
- ach binds to receptors on motor end plates
- sodium ions rush into muscle fibers
- muscle action potentioal sweeps into t tubules
- sr releases ca
- ca binds to troponin
- when ca binds to troponin, causes tropomyosin to shift and expose myosin binding site
- myosin binds to actin
- myosin pivots, pulling actin filaments
- myosin releases form actin
- myosin reextends to ready position
muscle contraction
- force of contrafction is generated by the process that slides the actin filament over the myosin filament
- lengths of the thick and thin filaments do not change during muscle contraction
- length of the sarcomere decreases as the actin filaments slide over myosin filaments and pull the z discs toward the center of the sarcomere
sliding filament theory basic principles
- 2 z lines
- I band =actin filaments achored to z lines
- A band=myosin filaments with some actin overlapped
- H zone has no actin present
sarcomere at REST
- actin filaments slide over myosin Filaments
- z lines pulled towards center
- I band shortens
- A band length doesnt change
- H zone disappears
- neither filament changes in length
sarcomere CONTRACTED
ATP is required for muscle contraction and the myosin ATPase is located on ___ of myosin crossbridge. breakdown of ATP releases energy for movement of crossbridge
head
sources of ATP include : ___,___,and ___
phosphagens, glycolysis
, oxidative phosphorylation
- rest
- spread of depolarization
- binding of calcium to troponin
- generation of force
Phases of ECC
crossbridge of myosin heads extend toward actin , ATP molecule is bound to crossbridge and tropomyosin blocks active sites on actin molecule during ___
rest phase of ECC
- action potential - nerve junction, ACh cross NM junction, receptors to sarcolemma and t-tubles to SR
- Calcium release to lateral sacs
phase 1 of ECC
calcium binds to Tn-C
- positional change
- active sites uncovered
phase 2 of ECC
-crossbridge cycling generates force, filaments slide past, and z lines drawn together
phase 3 of ECC
- cross bridge formation
- powerstroke myosin head swivel
3.separation of myosin and actin
when atp binds to myosin
4.activation of myosin heads when breakdown of ATP
crossbridge cycling
long thin protein in actin filament is known as
tropomyosin
end of the myosin cross bridge is known as
myosin head
- rest
- excitation coupling
- contraction
- recharging
phases of muscle contraction
distance between 2 z lines is called
sarcomere
length of the i band during contraction ____
shortens
motor nerve impulse
ach released
sarcolemma stimulated
3,1,2
actomyosin crossbridge formation, ATPase action, powerstroke
2,1,3
cisternae stimulated
calcium travels to actin
atp and calcium attracted
1,3,2
within sarcomere ,thick filaments runs the entire length of the a band and the a band is interrupted in the mid section by the h zone where there is no overlap of thick/thin filaments
true
troponin inhibits myosin from binding
motor nerve impulse
actomyosin formed
2,3,1
actomyosin formed
ATPase
crossbridge powerstroke swivel
sliding filament theory
crossbridge swivels,
motor nerve impulses cease
cacium pumped back into terminal cisternae
true
ATPase
breakdown ATP
release 12kcals
true
