Skeletal muscle contraction : Muscle physiology Animations
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- Опубликовано: 10 апр 2021
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Excitation-contraction coupling
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Definition: a process in which an initiating stimulus (e.g., AP, chemical stimulus) triggers an increase in intracellular Ca2+ and subsequent myofilament shortening, resulting in muscular contraction
Types
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Electromechanical coupling
Pharmacomechanical coupling
Description
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The mechanism by which the intracellular Ca2+ concentration increases differs for each muscle type.
Skeletal muscle: stimulus → opening of dihydropyridine receptors and ryanodine receptors → Ca2+ release from the SR
Smooth muscle: stimulus → Ca2+ influx from the extracellular space into the muscle cell
Cardiac muscle: stimulus → Ca2+ influx from the extracellular space into the muscle cell → Ca2+ release from the SR
At resting position, actin and myosin are unable to interact because they are inhibited by regulatory proteins. An initiating stimulus is needed to enable interaction between the myofilaments.
Mechanism: stimulus (AP) from efferent neuron → presynaptic voltage-gated Ca2+ channels open → ACh is released into the synaptic gap → ACh binds to postsynaptic ACh receptors → muscle cell depolarization that diffuses across the sarcolemma and into T-tubules → opening of voltage-sensitive dihydropyridine receptors (DHPR) in the T tubules and the mechanically coupled ryanodine receptors (RYR) in the SR → SR releases Ca2+ into the sarcoplasm → increased intracellular Ca2+
Steps of the contraction cycle (crossbridge cycling)
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Crossbridge formation: released intracellular Ca2+ binds to troponin C and causes a conformational change → tropomyosin moves away from the myosin binding site of the actin filament → myosin head binds actin at a 90° angle, forming a crossbridge
Powerstroke of the myosin head: myosin head releases phosphate (Pi)→ myosin head tilts by 45°, pulling myosin along actin → muscle shortens (contracts) → ADP is released
Loosening of the crossbridge: new ATP binds to myosin head → myosin head detaches from the actin filament → myosin returns to its original position
Reorientation of the myosin head: hydrolysis of ATP to ADP and Pi (both remain on the myosin head) → myosin head alters its conformation (changes to a “cocked state”) → myosin returns to its original position (ready to bind to actin again)
Replication of the cycle
If the Ca2+ concentration in the muscle cell remains elevated, a new cycle begins with crossbridge formation
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You are awesome sir.
So many years on RUclips but I never found content like this.
I know it's difficult to understand for the general population/other specialization but for science students like us, it's a diamond 💎💎 mine.
Thank you very much, sir. 🙏
Thank you so much
0
thank u from 🇮🇶iraq .Studying this at only 14 years old🥲🥲🇮🇶🫀
شرحيلنا بالعربي لان اني تخدير مرحلة ثانية وكلشي مفهمت 😔😂
عزاا واني مدرسه المتميزات وكلشي فهمت @@user-amory_99
I love you, the way you explain it makes me wanna learn biology
-Today-
I learnt this topic in college
Thanks for the revision
Keep it up
#athcreation
You sir have made this topic very easy to understand. Thankyou for everything !
What a Cristal clear knowledge you given us
I never see this process with animation and also this type indection ❤❤❤❤
Fully setified
Tysm
So good explanation, this way I understand more than when read our russian books (I’m russian-speaking). Thank u :3
Спасибо за подсказку! 😉
well articulated.
Thank you sir this video is really helpfull
I can't thank you enough!!
Watched about advert vid on yt about muscle contraction but understood only from your
Tysm
ruclips.net/video/tKcmUy80xBw/видео.htmlsi=h4phfIRnqY8O8QTo
Thankyou so much ❤️
you are unmatchable ❤
Tysm
ruclips.net/video/tKcmUy80xBw/видео.htmlsi=h4phfIRnqY8O8QTo
Can you plz inform me about the softwares used to compose this video
It's been very helpful . THANK YOU.
Glad it was helpful!
THANKYOU
very clear and easy to understand, thank you!
Glad it was helpful!
Thank u so much sir for all ur hardwork and dedication 🙂😃
Tysm for compliments 💓
🤗
Thank you so much that’s really helpful 👌💕
Ur most welcome
Very well explained, thank you!
Glad you enjoyed it!
finally i understanded, thank you very much 🥰🥰🥰🥰❤♥❤
You're welcome 😊
This was so wholesome 💫💫
Tysm
Thank you
Nice efforts.. brilliantly explained..👏👏
Thanks a lot 😊
Thanku u somuch akka😍😍
Good
Very nice animated video.
Very nicely explained.
Thank you teacher
ur most welcome
how A bands come closer together with there length constant ?
thank you
Tnq🥰
Thank you sir for informing us..
Keep watching
Thank u soo much❤
Always welcome
Tq sir ☺️
thank you very much
You are welcome
wow!!!!!
Thank you soo much sir.
Day after tomorrow is my internal exam
This helped me a lot
Thank you so much sir for the content. I'm a neet aspirant. Nd yes I'm referring your videos for my upcoming neet ug exm. Thanks a lot sir. Love from Assam.❤
All the best
@@doctorbhanuprakashthank you so much sir. Asirwad kijiyega sir ki iss bar seat mil Jaye.🙏🙏
Hello sir , great video as usual . I have a small doubt sir . If I buy the complete anatomy videos for 800/month in youtube , Will it unlock other extra anat videos which weren't avlb in the free version (which I am using) . Please clarify as I am planning to buy that for a month . Thank you :)
After purchasing contact +919885588972 .. my manager will give you the access to all anatomy videos via Www.medvizz.com site.
Very useful.untershood in this concept
Keep watching
I was so confused about this topic then i saw this video
You really made this in sequence which made my points more clear than before
You really helped me alot ♥️💕thankyou so much ♥️
You're most welcome
Amazing video
Thanks for the visit
amazing thanks
Ur most welcome
Thank you!
Ur most welcome
ruclips.net/video/tKcmUy80xBw/видео.htmlsi=h4phfIRnqY8O8QTo
nice sir❤
Thanks and welcome
why pronounce calcium as calshium? i noticed it in many videos by south Asian professors and doctors, is there a reason? Thanks for the response I'm curious!
That's who thy trach us in med schools but later we get corrected by someone, even I used to spell same and corrected later
Sir, ATP that binds with myosin head is comes from where ?
the ATP is already stored in the myosin head.
I understand, it is creatine phosphate, not creatinine phosphate
How ca(binded with troponin)returns to sarcoplasmic reticulum
it will unbind from troponin and then a Ca2+ ATPase pump will push the calcium back into SR. calcium also leaves the cell by Ca2+/Na+ antiporter, the calcium will leave and a sodium will enter.
Ok
Thanks for a very nice video !
BUT at 0:46 it is not correct. All motorneurons goes like the blue neuron: it starts in the anterior grey horn.
The green neuron is a sensory neuron connected to the posterior grey horn. But in the video it looks like actionpotential sends FROM the spinal chord via the green neuron. It could be confusing for students who have learned that all motor neurons goes out FROM the anterior grey horn .
Yes, you are right, we have corrected and uploaded in the website, this is older one.. Thank u for noticing
Thank you