GMS 6474 final exam Questions With Complete Solutions
what does the SR store Correct Answers proteins and calcium
...... .... ..
what is the role of the transverse tubules in the muscle fiber
Correct Answers allow inside of muscle to communicate with
...... ......
the outside of the muscle
how is a sarcomere measured Correct Answers from z-disc to z- ...... ......
disc
what is contained in the I band of the sarcomere & what color is
the band Correct Answers thin filaments
...... .... ..
titin
z-disc
light (isotropic)
what is contained in the A band of the sarcomere & what color
is the band Correct Answers thick filaments
...... ......
thin filaments
dark (scatters light)
what is contained in the H zone & what color is the band Correct ......
Answers thick filaments
.... ..
light
no barbs or myosin
middle zone of the sarcomere
what is contained in the M line Correct Answers in the middle of ...... ......
the sarcomere, middle of H zone
thick filaments
,myomesin
what does titin do in the sarcomere Correct Answers structural
...... ......
protein
how many zones can you see when the sarcomere is relaxed
Correct Answers all zones can be seen in relaxed state
...... ......
how many zones can be seen when the sarcomere is contracted
Correct Answers sarcomere shortens
...... ......
I band shortens
H zone disappears
thick and thin filaments overlap DONT shorten
what is the contractile unit of skeletal muscle Correct Answers
......
the sarcomere
......
what is the main component of the thick filaments Correct ......
Answers myosin
.... ..
have heavy and light chains
motor heads that move it along the thin filament
what is the largest protein in the body Correct Answers titin
...... ......
what are the main components of the thin filaments Correct ......
Answers actin (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 Correct Answers interacts
...... ......
with alpha-actinin to anchor z-disc to sarcolemma
what does dystrophin do in the sarcomere Correct Answers ......
connects sarcomere to sarcolemma
......
stabilizes the sarcolemma to prevent damage during contractions
1st step of cross-bridge cycle Correct Answers BINDING
...... ......
activated myosin binds to actin
ADP and Pi are still bound to myosin
2nd step of cross bridge cycle Correct Answers POWER
...... ......
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 Correct Answers
......
DISSOSCIATION
......
ATP binds to myosin
Actin and myosin dissociate (cross bridge detaches)
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 Correct Answers
......
Ca2+ 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
Correct Answers through 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 Correct ......
Answers release from rigor state
.... ..
re-energize/reactivate myosin heads for next cycle
what resequesters Ca2+ to end muscle contraction Correct ......
Answers SERCA
.... ..
where is the sarcoplasmic reticulum located Correct Answers
......
wrapped around the sarcomeres and throughout the myofibrils
......
what is the role of the sarcoplasmic reticulum in muscle cells
Correct Answers stores Ca2+ that is needed for contraction
...... ......
what are the components of the triad in the muscle cell Correct ......
Answers sarcoplasmic reticulum
.... ..
t-tubule
what is the role of the triad in the muscle cell Correct Answers
......
communication center
......
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