Search results
Results From The WOW.Com Content Network
In a normal wall of arteries, collagen type IV acts to inhibit smooth muscle cell proliferation. Accordingly, it was demonstrated that protein expression of collagen type IV in human vascular smooth muscle cells is regulated by both SMAD3 protein and TGFβ mediated stimulation of mRNA. [ 14 ]
Smooth muscle is grouped into two types: single-unit smooth muscle, also known as visceral smooth muscle, and multiunit smooth muscle. Most smooth muscle is of the single-unit type, and is found in the walls of most internal organs (viscera); and lines blood vessels (except large elastic arteries), the urinary tract , and the digestive tract .
Vascular smooth muscle cells also play important roles during development, e.g. driving osteocyte differentiation from undifferentiated precursors during osteogenesis. [1] Arteries have a great deal more smooth muscle within their walls than veins, thus their greater wall thickness. This is because they have to carry pumped blood away from the ...
The unusual microscopic anatomy of a muscle cell gave rise to its terminology. The cytoplasm in a muscle cell is termed the sarcoplasm; the smooth endoplasmic reticulum of a muscle cell is termed the sarcoplasmic reticulum; and the cell membrane in a muscle cell is termed the sarcolemma. [9] The sarcolemma receives and conducts stimuli.
Mural cells were described for the first time in the late 19th century as contractile cells lining up around the endothelium. In reality, it was a variety of cells that had been observed and bundled up under the common name of Rouget cells. Later studies brought controversy about their contractility, and this remains an elusive point today. [4]
Many smooth muscle cells in a transverse section through a muscle bundle show regions of very close apposition to adjacent cells at which connexins form junctions between the cells. Unlike in cardiac muscle, where gap junctions are confined to the ends of cardiac myocytes, smooth muscle gap junctions occur along the length of the muscle cells ...
When blood pressure is increased in the blood vessels and the blood vessels distend, they react with a constriction; this is the Bayliss effect. Stretch of the muscle membrane opens a stretch-activated ion channel. The cells then become depolarized and this results in a Ca 2+ signal and triggers muscle contraction. No action potential is ...
Because myosin undergoes a conformational change, the muscle will stay contracted even if calcium and activated MLC kinase concentrations are brought to normal levels. The conformational change must be undone to relax the muscle. [4] When myosin phosphatase binds to myosin, it removes the phosphate group. Without the group, the myosin reverts ...