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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 ]
A serous membrane lines the pericardial cavity of the heart, and reflects back to cover the heart, much like an under-inflated balloon would form two layers surrounding a fist. Called the pericardium, this serous membrane is a two-layered sac that surrounds the entire heart except where blood vessels emerge on the heart's superior side; [4]
The autonomic nervous system (ANS), sometimes called the visceral nervous system and formerly the vegetative nervous system, is a division of the nervous system that operates internal organs, smooth muscle and glands. [ 1 ] The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions, such as ...
Anatomical terminology. [ edit on Wikidata] The pleural cavity, pleural space, or intrapleural space is the potential space between the pleurae of the pleural sac that surrounds each lung. A small amount of serous pleural fluid is maintained in the pleural cavity to enable lubrication between the membranes, and also to create a pressure gradient.
Skeletal muscle (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the other being cardiac muscle and smooth muscle. They are part of the voluntary muscular system [ 1 ] and typically are attached by tendons to bones of a skeleton. [ 2 ][ 3 ] The skeletal muscle cells are much longer than in the other types ...
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 ...
The costal portion covers the inside of the rib cage. Some authors also designate a cervical portion (covering the underside of the suprapleural membrane). The pulmonary pleura covers the entire lung parenchyma. It meets the mediastinal pleura at the root of the lung ("hilum") through a smooth fold known as pleural reflection.
Cardiac muscle. Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissues, the others being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall of the heart. The cardiac muscle (myocardium) forms a thick middle layer between the ...