muscle contraction steps

Question 1

step one

Answer 1

• brain sends a signal to the motor neuron
• ACH is released by the motor neuron into the synapse and binds with ACH receptors

Question 2

step two

Answer 2

• if enough receptors are activated (hit threshold) then you will get a contraction
• an action potential will travel down sarcolemma

Question 3

step three

Answer 3

• signal/action potential travels along the membrane to the sarcoplasmic reticulum
• SR releases calcium (Ca^2+)

Question 4

step four

Answer 4

• Calcium causes the troponin to move the tropomyosin out of the way
• myosin binds with actin
• then muscle fiber contracts

Question 5

step five

Answer 5

• to relax, signal from brain stops
• ACH is no longer released and ACH-ase breaks down ACH in the synapse

Question 6

step six

Answer 6

• SR stops releasing calcium and pumps it back into the SR

Question 7

step seven

Answer 7

• the troponin allows the tropomyosin back into the location where it blocks the myosin binding sites
• relaxation