SGMS 6474 FINAL EXAM WITH
COMPLETE SOLUTION
what does the SR store - ANSproteins and calcium
what is the role of the transverse tubules in the muscle fiber - ANSallow inside of
muscle to communicate with the outside of the muscle
how is a sarcomere measured - ANSfrom z-disc to z-disc
what is contained in the I band of the sarcomere & what color is the band - ANSthin
filaments
titin
z-disc
light (isotropic)
what is contained in the A band of the sarcomere & what color is the band - ANSthick
filaments
thin filaments
dark (scatters light)
what is contained in the H zone & what color is the band - ANSthick filaments
light
no barbs or myosin
middle zone of the sarcomere
what is contained in the M line - ANSin the middle of the sarcomere, middle of H zone
thick filaments
myomesin
what does titin do in the sarcomere - ANSstructural protein
how many zones can you see when the sarcomere is relaxed - ANSall zones can be
seen in relaxed state
how many zones can be seen when the sarcomere is contracted - ANSsarcomere
shortens
I band shortens
,H zone disappears
thick and thin filaments overlap DONT shorten
what is the contractile unit of skeletal muscle - ANSthe sarcomere
what is the main component of the thick filaments - ANSmyosin
have heavy and light chains
motor heads that move it along the thin filament
what is the largest protein in the body - ANStitin
what are the main components of the thin filaments - ANSactin (where myosin binds)
troponin (moves tropomyosin when Ca2+ is present)
tropomyosin (covers actin active site)
nebulin (sets thin filament length)
CapZ (anchors actin to Z-line on z-disc side)
Tropomodulin (on end of actin, in middle of sarcomere)
alpha-actinin (anchors actin to z-line)
what does desmin do in the sarcomere - ANSinteracts with alpha-actinin to anchor z-
disc to sarcolemma
what does dystrophin do in the sarcomere - ANSconnects sarcomere to sarcolemma
stabilizes the sarcolemma to prevent damage during contractions
1st step of cross-bridge cycle - ANSBINDING
activated myosin binds to actin
ADP and Pi are still bound to myosin
2nd step of cross bridge cycle - ANSPOWER STROKE
myosin head swivels
movement of actin filament
ADP and Pi released from myosin
(Pi is released first, before ADP is released)
3rd step of cross bridge cycle - ANSDISSOSCIATION
ATP binds to myosin
Actin and myosin dissociate (cross bridge detaches)
4th step of cross bridge cycle - ANSACTIVATION
ATP hydrolysis energy activates myosin head
ADP and Pi remain bound to myosin
if Ca2+ still present, cycle continues
how does Ca2+ effect the cross bridge cycle - ANSCa2+ is needed for the troponin to
move the tropomyosin off the actin
, when Ca2+ runs out, the cross bridge cycle will stop
troponin has 4 Ca2+ binding sites
how does Ca2+ get into the cell to trigger the cross bridge cycle - ANSthrough the RyR
channels, which are activated by the DHPR channel mechanical change IN SKELETAL
MUSCLES
what are the two roles of ATP in the cross bridge cycle - ANSrelease from rigor state
re-energize/reactivate myosin heads for next cycle
what resequesters Ca2+ to end muscle contraction - ANSSERCA
where is the sarcoplasmic reticulum located - ANSwrapped around the sarcomeres and
throughout the myofibrils
what is the role of the sarcoplasmic reticulum in muscle cells - ANSstores Ca2+ that is
needed for contraction
what are the components of the triad in the muscle cell - ANSsarcoplasmic reticulum
t-tubule
what is the role of the triad in the muscle cell - ANScommunication center
what are the two main receptors in the triad - ANSdihydropyridine receptors (DHPR)
ryanodine receptors (RyR)
what is the role of the DHPR in the triad - ANSvoltage sensor
sense when action potential is moving down t-tubule
what is the role of the RyR in the triad - ANSCa2+ release channel
what kind of pennate muscle fiber formation has the most force production -
ANSmultipennate
what muscle fiber arrangement is best for speed - ANSwhen they are stacked on top of
each other (like a building)
what muscle fiber arrangement is best for strength - ANSwhen they are next to each
other (like a trailer)
have more tension
what kind of muscle contraction action has the most tension - ANSisometric contraction
how many endplates do muscle fibers have - ANSone endplate per muscle fiber
anaerobic muscle contraction - ANSshort term
COMPLETE SOLUTION
what does the SR store - ANSproteins and calcium
what is the role of the transverse tubules in the muscle fiber - ANSallow inside of
muscle to communicate with the outside of the muscle
how is a sarcomere measured - ANSfrom z-disc to z-disc
what is contained in the I band of the sarcomere & what color is the band - ANSthin
filaments
titin
z-disc
light (isotropic)
what is contained in the A band of the sarcomere & what color is the band - ANSthick
filaments
thin filaments
dark (scatters light)
what is contained in the H zone & what color is the band - ANSthick filaments
light
no barbs or myosin
middle zone of the sarcomere
what is contained in the M line - ANSin the middle of the sarcomere, middle of H zone
thick filaments
myomesin
what does titin do in the sarcomere - ANSstructural protein
how many zones can you see when the sarcomere is relaxed - ANSall zones can be
seen in relaxed state
how many zones can be seen when the sarcomere is contracted - ANSsarcomere
shortens
I band shortens
,H zone disappears
thick and thin filaments overlap DONT shorten
what is the contractile unit of skeletal muscle - ANSthe sarcomere
what is the main component of the thick filaments - ANSmyosin
have heavy and light chains
motor heads that move it along the thin filament
what is the largest protein in the body - ANStitin
what are the main components of the thin filaments - ANSactin (where myosin binds)
troponin (moves tropomyosin when Ca2+ is present)
tropomyosin (covers actin active site)
nebulin (sets thin filament length)
CapZ (anchors actin to Z-line on z-disc side)
Tropomodulin (on end of actin, in middle of sarcomere)
alpha-actinin (anchors actin to z-line)
what does desmin do in the sarcomere - ANSinteracts with alpha-actinin to anchor z-
disc to sarcolemma
what does dystrophin do in the sarcomere - ANSconnects sarcomere to sarcolemma
stabilizes the sarcolemma to prevent damage during contractions
1st step of cross-bridge cycle - ANSBINDING
activated myosin binds to actin
ADP and Pi are still bound to myosin
2nd step of cross bridge cycle - ANSPOWER STROKE
myosin head swivels
movement of actin filament
ADP and Pi released from myosin
(Pi is released first, before ADP is released)
3rd step of cross bridge cycle - ANSDISSOSCIATION
ATP binds to myosin
Actin and myosin dissociate (cross bridge detaches)
4th step of cross bridge cycle - ANSACTIVATION
ATP hydrolysis energy activates myosin head
ADP and Pi remain bound to myosin
if Ca2+ still present, cycle continues
how does Ca2+ effect the cross bridge cycle - ANSCa2+ is needed for the troponin to
move the tropomyosin off the actin
, when Ca2+ runs out, the cross bridge cycle will stop
troponin has 4 Ca2+ binding sites
how does Ca2+ get into the cell to trigger the cross bridge cycle - ANSthrough the RyR
channels, which are activated by the DHPR channel mechanical change IN SKELETAL
MUSCLES
what are the two roles of ATP in the cross bridge cycle - ANSrelease from rigor state
re-energize/reactivate myosin heads for next cycle
what resequesters Ca2+ to end muscle contraction - ANSSERCA
where is the sarcoplasmic reticulum located - ANSwrapped around the sarcomeres and
throughout the myofibrils
what is the role of the sarcoplasmic reticulum in muscle cells - ANSstores Ca2+ that is
needed for contraction
what are the components of the triad in the muscle cell - ANSsarcoplasmic reticulum
t-tubule
what is the role of the triad in the muscle cell - ANScommunication center
what are the two main receptors in the triad - ANSdihydropyridine receptors (DHPR)
ryanodine receptors (RyR)
what is the role of the DHPR in the triad - ANSvoltage sensor
sense when action potential is moving down t-tubule
what is the role of the RyR in the triad - ANSCa2+ release channel
what kind of pennate muscle fiber formation has the most force production -
ANSmultipennate
what muscle fiber arrangement is best for speed - ANSwhen they are stacked on top of
each other (like a building)
what muscle fiber arrangement is best for strength - ANSwhen they are next to each
other (like a trailer)
have more tension
what kind of muscle contraction action has the most tension - ANSisometric contraction
how many endplates do muscle fibers have - ANSone endplate per muscle fiber
anaerobic muscle contraction - ANSshort term
