{"id":16642,"date":"2025-10-26T12:00:01","date_gmt":"2025-10-26T15:00:01","guid":{"rendered":"https:\/\/mol-en.icb.usp.br\/?page_id=16642"},"modified":"2026-08-01T12:55:43","modified_gmt":"2026-08-01T15:55:43","slug":"8-1-muscle-tissue","status":"publish","type":"page","link":"https:\/\/mol-en.icb.usp.br\/index.php\/8-1-muscle-tissue\/","title":{"rendered":"8-1 Muscle tissue"},"content":{"rendered":"<p>The muscle cells are elongated and for this reason also called <strong>muscle fibers<\/strong>.<br \/>\nThere are three types of muscle cells with distinct morphological and functional features. All have contractile properties, in other words, they may shorten their lenghth and return to their former lenghth. They own distinct distributions in different organs and tissues.<br \/>\nAll muscle fibers have in common:<br \/>\n\u2013 the presence in their cytoplasm of a large amount of proteins whose arrangement produces their contraction, primarily myosin and actin (also called contractile proteins) associated to several other proteins. Their organization of these proteins is similar in the striated muscle fibers and differs in the smooth muscle cells.<br \/>\n\u2013 the capacity to generate tension and movement resulting from their contraction. As these cells are elongated, they can undergo significant longitudinal reduction generating movement. A contraction without shortening results in tension.<br \/>\nTwo types of muscle fibers form the striated muscle tissues due to the peculiar organization of their contractile proteins. Transverse bands can be observed along their cytoplasm when longitudinal sections of their fibers are viewed under a microscope. The arrangement of contractile proteins in the smooth muscle is quite different and as a consequence its cells do not show transverse bands. <\/p>\n<p>Main features of muscle cells:<br \/>\n\u2013 <strong>Skeletal striated muscle<\/strong> \u2013 of voluntary contraction constitutes the body&#8217;s musculature  attached to bones, as well as a few muscles not attached to bones, such as those present in the skin, the intrinsec muscles of the tongue, mimic muscles, the <em>orbicularis oculi<\/em>.<br \/>\n\u2013 <strong>Cardiac striated muscle<\/strong> \u2013 its contraction is involuntary. They are the muscle that make up the myocardium of the heart, also found in the initial portion of the aorta.<br \/>\n\u2013 <strong>Smooth muscle<\/strong> \u2013 its contraction is involuntary and constitutes the muscles of the viscera, of the walls of blood vessels and is found in several other places.<\/p>\n<p><a href=\"https:\/\/mol-en.icb.usp.br\/index.php\/8-2-Muscle-tissue\/\">NEXT PAGE<\/a><\/p>\n<p><a href=\"https:\/\/mol-en.icb.usp.br\/index.php\/8-0-muscle-tissue\/\">MENU OF THIS CHAPTER<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The muscle cells are elongated and for this reason also called muscle fibers. There are three types of muscle cells with distinct morphological and functional features. All have contractile properties, in other words, they may shorten their lenghth and return to their former lenghth. They own distinct distributions in different organs and tissues. All muscle [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-16642","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/mol-en.icb.usp.br\/index.php\/wp-json\/wp\/v2\/pages\/16642","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mol-en.icb.usp.br\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/mol-en.icb.usp.br\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/mol-en.icb.usp.br\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/mol-en.icb.usp.br\/index.php\/wp-json\/wp\/v2\/comments?post=16642"}],"version-history":[{"count":41,"href":"https:\/\/mol-en.icb.usp.br\/index.php\/wp-json\/wp\/v2\/pages\/16642\/revisions"}],"predecessor-version":[{"id":23686,"href":"https:\/\/mol-en.icb.usp.br\/index.php\/wp-json\/wp\/v2\/pages\/16642\/revisions\/23686"}],"wp:attachment":[{"href":"https:\/\/mol-en.icb.usp.br\/index.php\/wp-json\/wp\/v2\/media?parent=16642"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}