jacksonmeg
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Could somebody explain clearly how muscle contraction occur with reference to atp and calcium ions please? I really dont understand the book
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Dynamo123
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(Original post by jacksonmeg)
Could somebody explain clearly how muscle contraction occur with reference to atp and calcium ions please? I really dont understand the book
Well, you know that there are two proteins which are basic in muscle contraction: actin and myosin. Alongwith these, you have tropomyosin and troponin. For any process to occur against something, you need energy.Now myosin needs energy to attach actin. The myosin will achieve this energy by splitting ATP by means of an enzyme ATPase which is located on the myosin heads. Once ATP is split, myosin will cause muscle contraction by binding to actin and then releasing the energy.
Where does the role of Ca ions come in? In your muslce ER, called sarcoplasmic reticulum, Ca++ ions are stored in huge amounts. The normal active sites on actin used to bind myosin are covered by tropomyosin in the resting state. You need to displace this tropomyosin to expose the active binding sites. For this, Ca ions bind to yet another protein called troponin. This binding changes the structure of troponin and causes it to "pull" the tropomyosin away, exposing the actin binding sites for myosin to bind.
Here, it will do well for you to remember that the thick filament is composed of myosin, while the thin filament is actually a "complex" of actin (primarily), tropomyosin and troponin.
ATP is also required at some other stages, but this is the primary place where it's required.
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jacksonmeg
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(Original post by Dynamo123)
Well, you know that there are two proteins which are basic in muscle contraction: actin and myosin. Alongwith these, you have tropomyosin and troponin. For any process to occur against something, you need energy.Now myosin needs energy to attach actin. The myosin will achieve this energy by splitting ATP by means of an enzyme ATPase which is located on the myosin heads. Once ATP is split, myosin will cause muscle contraction by binding to actin and then releasing the energy.
Where does the role of Ca ions come in? In your muslce ER, called sarcoplasmic reticulum, Ca++ ions are stored in huge amounts. The normal active sites on actin used to bind myosin are covered by tropomyosin in the resting state. You need to displace this tropomyosin to expose the active binding sites. For this, Ca ions bind to yet another protein called troponin. This binding changes the structure of troponin and causes it to "pull" the tropomyosin away, exposing the actin binding sites for myosin to bind.
Here, it will do well for you to remember that the thick filament is composed of myosin, while the thin filament is actually a "complex" of actin (primarily), tropomyosin and troponin.
ATP is also required at some other stages, but this is the primary place where it's required.
thanks! this helps a lot, I have a couple more questions if you would be able to help
what is a striated muscle? I know cardiac and skeletal muscle are striated but the book keeps using the term but never explains what it means... also, what is a ganglion?
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Hype en Ecosse
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(Original post by jacksonmeg)
thanks! this helps a lot, I have a couple more questions if you would be able to help
what is a striated muscle? the book keeps using the term but never explains what it means... also, what is a ganglion?
Striated muscle is skeletal muscle. It just means it has a "striated" pattern!

A ganglion is a little collection of nerve cell bodies outside of the brain/spinal cord.
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jacksonmeg
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(Original post by Hype en Ecosse)
Striated muscle is skeletal muscle. It just means it has a "striated" pattern!

A ganglion is a little collection of nerve cell bodies outside of the brain/spinal cord.
oh... I thought it was something important, thanks now I just need to somehow memorise all the plant hormone stuff
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jacksonmeg
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(Original post by Hype en Ecosse)
Striated muscle is skeletal muscle. It just means it has a "striated" pattern!

A ganglion is a little collection of nerve cell bodies outside of the brain/spinal cord.
any tips? it seems like every hormone does everything...
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Dynamo123
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(Original post by jacksonmeg)
thanks! this helps a lot, I have a couple more questions if you would be able to help
what is a striated muscle? I know cardiac and skeletal muscle are striated but the book keeps using the term but never explains what it means... also, what is a ganglion?
Like Hype said, a striated muscle is a muscle that has a striated pattern. You know about the thick and the thin filaments present in skeletal and cardiac muscles. Now on a procedure which we normally use to view the muscle, these filaments appear as alternate thick and thin bands. This alternate appearance looks like stripes or striations.

(Original post by jacksonmeg)
any tips? it seems like every hormone does everything...
Well, this is kinda confusing. Just remember the main function each hormone performs, which is going to be different for each, e.g. cytokinins do something fundamentally different from giberrelins. Then you can learn the common functions and apply them.

Another way is to make a chart or map of these functions and along with each function draw a little cartoon to help you remember the concept.
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