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Smooth muscle cells. A smooth-muscle cell is a spindle-shaped myocyte with a wide middle and tapering ends, and a single nucleus. Like striated muscle, smooth muscle can tense and relax. In the relaxed state, each cell is 30–200 micrometers in length, some thousands of times shorter than a skeletal muscle cell. [ 1 ]
The muscular system is an organ system consisting of skeletal, smooth, and cardiac muscle. It permits movement of the body, maintains posture, and circulates blood throughout the body. [1] The muscular systems in vertebrates are controlled through the nervous system although some muscles (such as the cardiac muscle) can be completely autonomous ...
Only skeletal and smooth muscles are part of the musculoskeletal system and only the muscles can move the body. Cardiac muscles are found in the heart and are used only to circulate blood; like the smooth muscles, these muscles are not under conscious control. Skeletal muscles are attached to bones and arranged in opposing groups around joints. [8]
abducts, intorts, and depress eye. right medial, superior, and inferior recti (superior and inferior oblique muscles are the synergists) 2. 1. oblique, inferior. head, extraocular (left/right) orbital surface of maxilla, lateral to lacrimal groove. laterally onto eyeball, deep to lateral rectus, by a short flat tendon.
Venule. A venule is a very small vein in the microcirculation that allows blood to return from the capillary beds to drain into the venous system via increasingly larger veins. Post-capillary venules are the smallest of the veins with a diameter of between 10 and 30 micrometres (μm). When the post-capillary venules increase in diameter to ...
Motor protein. Kinesin "walking" on a microtubule using protein dynamics on nanoscales. Motor proteins are a class of molecular motors that can move along the cytoskeleton of cells. They convert chemical energy into mechanical work by the hydrolysis of ATP. Flagellar rotation, however, is powered by a proton pump. [citation needed]
The iris (brown coloured portion of the eye) controls the size of the pupil by contracting the sphincter pupillae and dilator pupillae muscles. The sphincter pupillae is the opposing muscle of the dilator pupillae. The pupil's diameter, and thus the inner border of the iris, changes size when constricting or dilating.
Vascular smooth muscle contracts or relaxes to change both the volume of blood vessels and the local blood pressure, a mechanism that is responsible for the redistribution of the blood within the body to areas where it is needed (i.e. areas with temporarily enhanced oxygen consumption). Thus the main function of vascular smooth muscle tone is ...