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Smooth muscle (also known as visceral muscle due to the locations in which they are present<ref>Rodney R., (2002) Human Physiology, 6th Edition, Pacific Grove, California; London: Brooks/Cole</ref>) is one of the three main types of muscle tissue that exist in the human body <ref>Barrett K. E., Barman S. M., Botiano S., Brooks H. L. (2010) Ganong’s Review of Medical Physiology, 23rd edition, New York: McGraw Hill</ref> . Smooth muscle is under involuntary control <ref>Koeppen B. M., Stanton B. A. (2008) Berne &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Levy Physiology, 6th edition, Philadelphia: Mosby Elsevier</ref> and is innervated by the autonomic nervous system <ref>The Human Body in Health and Disease 5th edition by Thibodeau, Patton (2010), page 267</ref>. Smooth muscle lines the walls of hollow organs such as the bladder <ref>Silverthorn D. U., Johnson B. R., Ober W. C., Garrison C. W., Silverthorn A. C. (2010) Human Physiology, 5th edition, San Francisco: Pearson</ref> . Smooth muscle cells compose [https://bms.ncl.ac.uk/wiki/index.php/Myosin myosin] myofilaments dispersed throughout the muscle cell cytoplasm and filaments of [[Actin|actin]] held together in contracile bundles.[[Intermediate filaments|Intermediate filaments]] exist between contractile bundles connecting them, and they are anchored by dense plaque-like bodies. <ref>. [Becker W.M, Kleinsmith L.J, Hardin J, Bertoni G.P, 2009, The World of the Cell, 7th edition, Pearson]</ref> The contractile filament bundles of [https://bms.ncl.ac.uk/wiki/index.php/Actin actin] and [https://bms.ncl.ac.uk/wiki/index.php/Myosin myosin] are loosely arranged in a diagonal fashion, in different directions around the perimeter of the smooth muscle cell. This arrangement of fibres causes the muscle cell to become globular upon contraction.<ref>Silverthorn.D. U (2009) Human Physiology: An Integrated Approach, 5th Edition, Cambridge, UK: Pearson</ref> Smooth muscle cells are fusiforn in shape meaning that they are wide in the middle with tapered ends, they also have only a single nucleus. Smooth muscle cells do not contain the sarcomeres found in skeletal muscle and therefore appear unstriated under a microscope <ref>Fundamentals of Anatomy and Physiology 5th edition by F H Martini (Chapter 10, Smooth muscle tissue)</ref>. | Smooth muscle (also known as visceral muscle due to the locations in which they are present<ref>Rodney R., (2002) Human Physiology, 6th Edition, Pacific Grove, California; London: Brooks/Cole</ref>) is one of the three main types of muscle tissue that exist in the human body <ref>Barrett K. E., Barman S. M., Botiano S., Brooks H. L. (2010) Ganong’s Review of Medical Physiology, 23rd edition, New York: McGraw Hill</ref> . Smooth muscle is under involuntary control <ref>Koeppen B. M., Stanton B. A. (2008) Berne &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Levy Physiology, 6th edition, Philadelphia: Mosby Elsevier</ref> and is innervated by the autonomic nervous system <ref>The Human Body in Health and Disease 5th edition by Thibodeau, Patton (2010), page 267</ref>. Smooth muscle lines the walls of hollow internal organs such as the bladder and intestine <ref>Silverthorn D. U., Johnson B. R., Ober W. C., Garrison C. W., Silverthorn A. C. (2010) Human Physiology, 5th edition, San Francisco: Pearson</ref>, organs of this type are known as viscera. Smooth muscle cells compose [https://bms.ncl.ac.uk/wiki/index.php/Myosin myosin] myofilaments dispersed throughout the muscle cell cytoplasm and filaments of [[Actin|actin]] held together in contracile bundles.[[Intermediate filaments|Intermediate filaments]] exist between contractile bundles connecting them, and they are anchored by dense plaque-like bodies. <ref>. [Becker W.M, Kleinsmith L.J, Hardin J, Bertoni G.P, 2009, The World of the Cell, 7th edition, Pearson]</ref> The contractile filament bundles of [https://bms.ncl.ac.uk/wiki/index.php/Actin actin] and [https://bms.ncl.ac.uk/wiki/index.php/Myosin myosin] are loosely arranged in a diagonal fashion, in different directions around the perimeter of the smooth muscle cell. This arrangement of fibres causes the muscle cell to become globular upon contraction.<ref>Silverthorn.D. U (2009) Human Physiology: An Integrated Approach, 5th Edition, Cambridge, UK: Pearson</ref> Smooth muscle cells are fusiforn in shape meaning that they are wide in the middle with tapered ends, they also have only a single nucleus. Smooth muscle cells do not contain the sarcomeres found in skeletal muscle and therefore appear unstriated under a microscope <ref>Fundamentals of Anatomy and Physiology 5th edition by F H Martini (Chapter 10, Smooth muscle tissue)</ref>. | ||
There are two types of smooth muscle cell, multi- unit and single unit smooth muscle. Single-unit smooth muscle cells are connected by gap junctions that electrically connect cells to one another, so contract as a single unit. These can be found in the intestinal tract. Multi-unit cells lack gap junctions, so are not linked electrically. They must be stimulated independently, which allows fine control of contractions by selective activation of individual muscle cells. Multi-unit cells can be found in the eye <ref>Silverthorn D., Johnson B., Ober W., Garrison C., Silverthorn A. (2010) Human Physiology: An Integrated Approach, 5th edition, San Francisco: Pearson Education</ref>. | There are two types of smooth muscle cell, multi- unit and single unit smooth muscle. Single-unit smooth muscle cells are connected by gap junctions that electrically connect cells to one another, so contract as a single unit. These can be found in the intestinal tract. Multi-unit cells lack gap junctions, so are not linked electrically. They must be stimulated independently, which allows fine control of contractions by selective activation of individual muscle cells. Multi-unit cells can be found in the eye <ref>Silverthorn D., Johnson B., Ober W., Garrison C., Silverthorn A. (2010) Human Physiology: An Integrated Approach, 5th edition, San Francisco: Pearson Education</ref>. | ||
Revision as of 01:51, 2 December 2011
Smooth muscle (also known as visceral muscle due to the locations in which they are present[1]) is one of the three main types of muscle tissue that exist in the human body [2] . Smooth muscle is under involuntary control [3] and is innervated by the autonomic nervous system [4]. Smooth muscle lines the walls of hollow internal organs such as the bladder and intestine [5], organs of this type are known as viscera. Smooth muscle cells compose myosin myofilaments dispersed throughout the muscle cell cytoplasm and filaments of actin held together in contracile bundles.Intermediate filaments exist between contractile bundles connecting them, and they are anchored by dense plaque-like bodies. [6] The contractile filament bundles of actin and myosin are loosely arranged in a diagonal fashion, in different directions around the perimeter of the smooth muscle cell. This arrangement of fibres causes the muscle cell to become globular upon contraction.[7] Smooth muscle cells are fusiforn in shape meaning that they are wide in the middle with tapered ends, they also have only a single nucleus. Smooth muscle cells do not contain the sarcomeres found in skeletal muscle and therefore appear unstriated under a microscope [8].
There are two types of smooth muscle cell, multi- unit and single unit smooth muscle. Single-unit smooth muscle cells are connected by gap junctions that electrically connect cells to one another, so contract as a single unit. These can be found in the intestinal tract. Multi-unit cells lack gap junctions, so are not linked electrically. They must be stimulated independently, which allows fine control of contractions by selective activation of individual muscle cells. Multi-unit cells can be found in the eye [9].
References
- ↑ Rodney R., (2002) Human Physiology, 6th Edition, Pacific Grove, California; London: Brooks/Cole
- ↑ Barrett K. E., Barman S. M., Botiano S., Brooks H. L. (2010) Ganong’s Review of Medical Physiology, 23rd edition, New York: McGraw Hill
- ↑ Koeppen B. M., Stanton B. A. (2008) Berne &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Levy Physiology, 6th edition, Philadelphia: Mosby Elsevier
- ↑ The Human Body in Health and Disease 5th edition by Thibodeau, Patton (2010), page 267
- ↑ Silverthorn D. U., Johnson B. R., Ober W. C., Garrison C. W., Silverthorn A. C. (2010) Human Physiology, 5th edition, San Francisco: Pearson
- ↑ . [Becker W.M, Kleinsmith L.J, Hardin J, Bertoni G.P, 2009, The World of the Cell, 7th edition, Pearson]
- ↑ Silverthorn.D. U (2009) Human Physiology: An Integrated Approach, 5th Edition, Cambridge, UK: Pearson
- ↑ Fundamentals of Anatomy and Physiology 5th edition by F H Martini (Chapter 10, Smooth muscle tissue)
- ↑ Silverthorn D., Johnson B., Ober W., Garrison C., Silverthorn A. (2010) Human Physiology: An Integrated Approach, 5th edition, San Francisco: Pearson Education