contraction of muscle skeletal fiber

Question 1

first

Answer 1

electrical impulses travels down the axon of the motor neuron reaching the synaptic knob.

Question 1

second

Answer 1

this causes voltage gated calcium (ca) ion channels to open.

Question 2

third

Answer 2

calcium rushes into the synaptic knob.

Question 3

fourth

Answer 3

this causes acetylcholine (ach) vesicles to release ach into the synaptic cleft by exocytosis.

Question 4

fifth

Answer 4

ach diffuses across the synaptic cleft.

Question 5

sixth

Answer 5

ach attaches to ach receptors in the post synaptic membrane.

Question 6

seventh

Answer 6

ach receptors open.

Question 7

eighth

Answer 7

sodium ions rush into the receptors and potassium rushes out.

Question 8

ninth

Answer 8

this voltage change is known as an end plate potential.

Question 9

tenth

Answer 9

the electrical impulse causes sodium ion channels to open, causing a wave of depolarization.

Question 10

eleventh

Answer 10

almost simultaneously potassium ion channels open, causing a wave of repolarization.

Question 11

twenth

Answer 11

the electrical impulse travels down a transverse tubule.

Question 12

thirteenth

Answer 12

the electrical impulse is transferred to the terminal cisternae of the sarcoplasmic reticulum.

Question 13

fourteenth

Answer 13

this causes voltage gated calcium channel ions to open.

Question 14

fifteenth

Answer 14

calcium rushes into the sarcoplasm.

Question 15

sixteenth

Answer 15

calcium binds to troponin on the thin filament.

Question 16

seventeenth

Answer 16

this causes tropomyosin to shift revealing active sites on the thin filament.

Question 17

eighteenth

Answer 17

the thin filament is prepared to contract, in reality the thick filament is already prepared and the muscle contracts immediately.

Question 18

first in thick filament

Answer 18

ATP binds to a myosin head.

Question 19

second

Answer 19

myosin atpase splits ATP into ADP and a phosphate.

Question 20

third

Answer 20

energy is released into the myosin head causing it to extend into a high energy position.

Question 21

fourth

Answer 21

the myosin head binds to an active site on the thin filament.

Question 22

fifth

Answer 22

the ADP and phosphate are released from the myosin head.

Question 23

sixth

Answer 23

the myosin head flexes into a low energy position while attached to the thin filament.

Question 24

seventh

Answer 24

this is called power stroke.

Question 25

eight

Answer 25

the myosin head releases from the active site of the thin filament when a new ATP attached to the myosin head.

Question 26

ninth

Answer 26

as a result, the sarcomere shortens, myofibers shorten, muscle fibers shorten, fascicles shorten, and the muscle contracts.