Ca role in skeletal and cardiac muscle contraction

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sarita0518
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Joined: Fri Feb 22, 2019 3:08 pm

Ca role in skeletal and cardiac muscle contraction

Post by sarita0518 » Mon May 13, 2019 11:38 pm

Can you please tell me the difference in Ca role between skeletal and cardiac muscle contraction.
NS_Tutor_Will
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Joined: Fri May 25, 2018 9:15 am

Re: Ca role in skeletal and cardiac muscle contraction

Post by NS_Tutor_Will » Tue May 14, 2019 8:43 am

Is there a particular part of it that you're finding to be confusing? I'd be glad to address any specifics, but it's hard to go into a lot of depth on the forum. I'd recommend the NS content review videos on muscle and another one on neurons and signal transduction -- these'll get to the specific function of calcium in different settings.

At root, calcium's role is to change membrane potential or to alter some other protein's function so that additional downstream effects can occur, leading to some behavior by a cell. It gets pretty complicated, but the videos do a good job of getting at the heart of what you need to know!
sarita0518
Posts: 143
Joined: Fri Feb 22, 2019 3:08 pm

Re: Ca role in skeletal and cardiac muscle contraction

Post by sarita0518 » Tue May 14, 2019 10:12 am

Yes, can you tell me how the ATP pump works on calcium from the SR and extracellular environment (in which way does the pump cause ca to go)
I understand the muscle contraction part- it is the ca storage that I would like clarification on. Thank you!
NS_Tutor_Will
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Joined: Fri May 25, 2018 9:15 am

Re: Ca role in skeletal and cardiac muscle contraction

Post by NS_Tutor_Will » Tue May 14, 2019 2:39 pm

Great question! The sarcoplasmic reticulum is the storage site for calcium ions in a muscle cell. Since they are concentrated in the SR, to move calcium into the SR requires active transport (because it's against the gradient). Thus, the ATP-powered transporter moves Ca(2+) into the SR. When the muscle goes to contract, the calcium is released and it passively flows out of the SR.

I hope this helps!
sarita0518
Posts: 143
Joined: Fri Feb 22, 2019 3:08 pm

Re: Ca role in skeletal and cardiac muscle contraction

Post by sarita0518 » Wed May 15, 2019 4:27 pm

this does, thank you!
Is this the mechanism for both skeletal and cardiac muscle cells?
Also, does the ATP pump also pump the Ca(2+) out of the cell too or just back into the SR only?
NS_Tutor_Will
Posts: 766
Joined: Fri May 25, 2018 9:15 am

Re: Ca role in skeletal and cardiac muscle contraction

Post by NS_Tutor_Will » Thu May 16, 2019 8:13 am

Yes, they're very similar with some differences to account for the different functions and structures in the two muscle types. More on the heart here: https://www.khanacademy.org/science/hea ... s-up-close

The ATP pumps the Ca2+ into the SR as much as possible because the goal is to conserve and reuse it. I'm sure some gets out because there's always some spillage/waste, but that's definitely not the preferred outcome!
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