Steps of Skeletal Muscle Contraction and Relaxation

Created by shari_walker1 

Upgrade to
remove ads

10 terms · Steps of Skeletal Muscle Contraction and Relaxation

Step 1

A nerve impulse travels down and axon and causes the release of acetylcholine.

Step 2

Acetylecholine causes the impulse to spread across the surface of the sarcolemma.

Step 3

The nerve impulse enters the T Tubules and Sarcoplasmic Reticulum, stimulating the release of calcium ions.

Step 4

Calcium ions combine with Troponin, shifting troponin and exposing the myosin binding sites on the actin.

Step 5

ATP breaks down ADP + P. The released energy activates the myosin cross bridges and results in the sliding of thin actin myofilament past the thick myosin myofilaments.

Step 6

The sliding of the myofilaments draws the Z lines towards each other, the sarcomere shortens, the muscle fibers contract and therefore muscle contracts.

Step 7

ACh is inactivated by Acetylcholinesterase, inhibiting the nerve impulse conduction across the sarcolemma.

Step 8

Nerve impulse is inhibited, calcium ions are actively transported back into the Sarcoplasmic Reticulum, using the energy from the earlier ATP breakdown.

Step 9

The low calcium concentration causes the myosin cross bridges to separate from the think actin myofilaments and the actin myofilaments return to their relaxed position.

Step 10

Sarcomeres return to their resting lengths, muscle fibers relax and the muscle relaxes.

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

NEW! Voice Recording

Click the mic to start.

Create Set