ANATOMY&PHYSIOLOGY FOR NURSES

Unstriped ( unstriated, smooth, or involuntary muscle). This type will contract without nervous stimulation although in most parts of the body its activity is under the control of the autonomic (involuntary ) nervous system. With the exception elongated spindle-shaped muscle cells which retain the appearance of a cell.               Involuntary muscle is found in the coats of blood and lymphatic vessels, in the walls of the digestive tract and the hollow viscera, trachea, and bronchi, in the iris and cillary muscle of the eye, and in the skin. A sphincter muscle is composed of a circular band of muscle fibres situated at the internal or external openings of a canal, or at the mouth of an orifice, tightly closing it When Contracted. Examples include the cardiac and pyloric sphincter or valve, the internal and external sphincters of the anus and urethra.

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ANATOMY&PHYSIOLOGY FOR NURSES

MUSCULAR-NERVOUS-CONNECTIVE TISSUE Muscular Tissue. Muscle is a tissue which is specialised for contraction, and by means of this, movements are performed. it is composed of cylindrical fibres which correspond to the cells of other tissues. These are bound together into little bundles of fibres by a form of connective tissue which contains a highly specialised contractile element. There are three types of muscle: Striped (Striated, skeletal or voluntary muscle). The individual muscle fibres are transversely striated by alternate light and dark markings. Each fibre is enclosed in a fine membrane - the Sarcolemma ( meaning - muscle sheath). A number of fibres are massed together to form bundles; to form large and small muscles.  When a muscle contracts it shortens, and each individual fibre takes part in the movement by contracting. This type only contracts when stimulated to do so by the nervous system.

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ANATOMY&PHYSIOLOGY FOR NURSES

MEMBRANES.  Layers of specialized cells which line the cavities of the body are described as membrane.  The three principal membranes are; Mucous membrane Synovial membrane Serous membrane All these membranes secrete a fluid to lubricate or moisten the cavity they line. Mucous Membranes is found lining the alimentary tract, the respiratory tract, and parts of the genito-urinary tract. It varies in character in the different areas. In the digestive tract it consists of columnar epithelial cells closely packed together. Some of them  become distended with mucous secretion and are then called goblet cells. The cell becomes more and more distended and finally ruptures and discharges its secretion on to the surface. Mucus is  the secretion of the membrane and consists of water,salts, and a protein, mucin, which gives the sticky or viscid character to the secretion. Synovial Membrane lines the cavities of joints. It consists of fine connective tissue, with a layer of squamous endothelial cells on the surface. The secretion of synovial membrane is thick and glairy in character. Serous Membranes are found in the chest and abdomen, covering the organs contained therein and lining these cavities. The pleura covers the lungs and lines the thorax The pericardium covers the heart as a double layer. The peritoneum covers the abdominal organs and lines the abdomen. ( These membranes are described in the chapters dealing with these various organs.)        The characteristics which are common to all three serous membranes are, that each consists of a double layer of membrane having an intervening potential cavity which receives the fluid secreted by the membrane. This serous fluid is very similar to blood serum or lymph.  It acts as a lubricant, and in addition it contains protective substances, and removes harmful products, passing these on to the lymphatic system to be dealt with.

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