Sacroplasmic reticulum: Difference between revisions
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The Sarcoplasmic Reticulum (SR) is present in all types of muscle cell (cardiac, smooth and skeletal) and is a form of modified | The Sarcoplasmic Reticulum (SR) is present in all types of muscle cell (cardiac, smooth and skeletal) and is a form of modified [[Endoplasmic_Reticulum|endoplasmic reticulum]].<ref name="null">D.U. Silverthorn, 2010, Human Physiology An Integrated Approach, 5th Edition, Sanfrancisco, Pearson. Page 408</ref> It contains an essential store of Ca2+ ions; when the SR is stimulated these ions are released to initiate a contration in the muscle. In other words, the sarcoplasmic reticulum regulates the intracellular concentration of calcium ions.<ref>B. M. Koeppen &amp;amp; B. A. Stanton, 2008, Berne &amp;amp; Levy Physiology, 6th Edition, Canada: Mosby Elesevier. Page 234.</ref> | ||
In cardiac and skeletal muscle cells the SR surrounds the myofibril and release their Ca2+ ions at areas known as terminal cisternae. Terminal cisternae are the part of the sarcoplasmic reticumlum nearest T-tubules. Skeletal and cardiac sarcoplasmic reticulums are similar in this way; however cardiac cells SRs are undeveloped and less dense in comparisson to skeletal cells.<ref>B. M. Koeppen &amp; B. A. Stanton, 2008, Berne &amp; Levy Physiology, 6th Edition, Canada: Mosby Elesevier. Page 258</ref> | In cardiac and skeletal [[Muscle|muscle]] cells the SR surrounds the [[Myofibrils|myofibril]] and release their Ca2+ ions at areas known as terminal cisternae. Terminal cisternae are the part of the sarcoplasmic reticumlum nearest [[T-tubules|T-tubules]]. Skeletal and cardiac sarcoplasmic reticulums are similar in this way; however cardiac cells SRs are undeveloped and less dense in comparisson to skeletal cells.<ref>B. M. Koeppen &amp;amp; B. A. Stanton, 2008, Berne &amp;amp; Levy Physiology, 6th Edition, Canada: Mosby Elesevier. Page 258</ref> | ||
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Smooth muscle cells also contain a sarcoplasmic reticulum that extends throughout the cell, in contrast to the other muscle types though, smooth muscles do not contain T-tubules and instead have junctional regions of the sarcoplasmic reticulum that abut areas of the sarcolema or caveolae.<ref>B. M. Koeppen &amp; B. A. Stanton, 2008, Berne &amp; Levy Physiology, 6th Edition, Canada: Mosby Elesevier. Page 271.</ref> Furthermore, Ca2+ ions are not only released from the SR in smooth muscle cells but also come from the extracellular fluid during musclular contraction.<ref>D.U. Silverthorn, 2010, Human Physiology An Integrated Approach, 5th Edition, Sanfrancisco, Pearson. Page 434.</ref> | Smooth muscle cells also contain a sarcoplasmic reticulum that extends throughout the cell, in contrast to the other muscle types though, smooth muscles do not contain T-tubules and instead have junctional regions of the sarcoplasmic reticulum that abut areas of the sarcolema or caveolae.<ref>B. M. Koeppen &amp;amp; B. A. Stanton, 2008, Berne &amp;amp; Levy Physiology, 6th Edition, Canada: Mosby Elesevier. Page 271.</ref> Furthermore, Ca2+ ions are not only released from the SR in smooth muscle cells but also come from the extracellular fluid during musclular contraction.<ref>D.U. Silverthorn, 2010, Human Physiology An Integrated Approach, 5th Edition, Sanfrancisco, Pearson. Page 434.</ref> | ||
== References == | == References == | ||
<references /> | <references /> | ||
Revision as of 09:30, 29 November 2011
The Sarcoplasmic Reticulum (SR) is present in all types of muscle cell (cardiac, smooth and skeletal) and is a form of modified endoplasmic reticulum.[1] It contains an essential store of Ca2+ ions; when the SR is stimulated these ions are released to initiate a contration in the muscle. In other words, the sarcoplasmic reticulum regulates the intracellular concentration of calcium ions.[2]
In cardiac and skeletal muscle cells the SR surrounds the myofibril and release their Ca2+ ions at areas known as terminal cisternae. Terminal cisternae are the part of the sarcoplasmic reticumlum nearest T-tubules. Skeletal and cardiac sarcoplasmic reticulums are similar in this way; however cardiac cells SRs are undeveloped and less dense in comparisson to skeletal cells.[3]
Smooth muscle cells also contain a sarcoplasmic reticulum that extends throughout the cell, in contrast to the other muscle types though, smooth muscles do not contain T-tubules and instead have junctional regions of the sarcoplasmic reticulum that abut areas of the sarcolema or caveolae.[4] Furthermore, Ca2+ ions are not only released from the SR in smooth muscle cells but also come from the extracellular fluid during musclular contraction.[5]
References
- ↑ D.U. Silverthorn, 2010, Human Physiology An Integrated Approach, 5th Edition, Sanfrancisco, Pearson. Page 408
- ↑ B. M. Koeppen &amp; B. A. Stanton, 2008, Berne &amp; Levy Physiology, 6th Edition, Canada: Mosby Elesevier. Page 234.
- ↑ B. M. Koeppen &amp; B. A. Stanton, 2008, Berne &amp; Levy Physiology, 6th Edition, Canada: Mosby Elesevier. Page 258
- ↑ B. M. Koeppen &amp; B. A. Stanton, 2008, Berne &amp; Levy Physiology, 6th Edition, Canada: Mosby Elesevier. Page 271.
- ↑ D.U. Silverthorn, 2010, Human Physiology An Integrated Approach, 5th Edition, Sanfrancisco, Pearson. Page 434.