calcium muscle tubule shit

Question 1

sarcoplasmic reticulum

Answer 1

functions in the regulation of intracellular calcium ion levels
electrical signals travel like a wave across the sarcolemma in all directions

Question 2

t tubule

Answer 2

continuous with the sarcolemma
penetrates cell’s interior at each A band-I band junction
electrical wave travels down t tubules causing protein to change shape, causing calcium to be dumped on top of the A band
the calcium then binds to troponin which moves tropomyosin out of blocking position and allows myosin to bind to actin for contraction to begin.

Question 3

t tubule function

Answer 3

conduct impulses deep into muscle fiber

Question 4

how do electrical impulses enter the muscle cell

Answer 4

each axon of a motor neuron forms a neuromuscular junction with a single muscle fiber with the space of the synaptic cleft

Question 5

how do the electrical impulses enter the muscle cell pt 2?

Answer 5

the action potential arrives at the axon terminal of motor neuron and the calcium channels open to get calcium through

Question 6

after the calcium goes through…

Answer 6

ACh is released and binds to receptors that open sodium potassium pumps there is local depolarization generation on the sarcolemma
this is the wave of depolarization as calcium ions travel across sarcolemma.

Question 7

generation and propagation of an action potential

Answer 7

when the sodium flows in from the channel, the influx decreases the voltage of the sarcolemma to a threshold.
once the threshold is released, an action potential is generated

Question 8

repolarization

Answer 8

sodium channels close and potassium ones open
potassium ions restore polarity

Question 9

when the action potential moves to the triad…

Answer 9

there is excitation contraction (EC) coupling
the action potential is propagated and goes down the t tubules and releases calcium ions into terminal cisternae of sarcoplasmic reticulum

Question 10

after the calcium is released in the sarcoplasmic reticulum…

Answer 10

the calcium binds to troponin and moves the tropomyosin blocking sites so that myosin can bind to actin and contraction can begin after cross bridge between myosin and actin forms

Question 10

after the calcium is released in the sarcoplasmic reticulum…

Answer 10

the calcium binds to troponin and moves the tropomyosin blocking sites so that myosin can bind to actin and contraction can begin

Question 11

to stop contraction….

Answer 11

calcium is pumped back into the sarcoplasmic reticulum (active transport)
cross bridge detaches (atp attaches to myosin head)
cocking of myosin head (hydrolysis from breakdown of atp releases energy that cocks myosin head into high energy- ADP and P form)
ACh decomposes and the membrane is no longer stimulated