100 VETERINAEY STATE BOARD 



of nerve cells bound together by a delicate connective-tissue net- 

 work; a number of these collections, united together and covered 

 by neurilemma, constitute a nerve. Blood-vessels traverse the 

 connective tissue. On the upper root of all the spinal and on the 

 track of certain other nerves are masses of nerve cells, ganglia. 

 The function of nerves is to conduct impulses to and from the 

 brain and spinal cord. 



Describe the structure of voluntary muscle. 



Voluntary muscle is made up of a great number of fibres which 

 are marked by transverse furrows or striae, giving rise to the term 

 striated or striped muscle. Each fibre is made up of fibrils and 

 these in turn can be subdivided into fibrillse or sarcous elements, 

 attached to each other end to end. The muscle fibres unite to form 

 secondary fasciculi which are covered by a connective sheath, the 

 internal perimysium. The secondary fasciculi unite to form more 

 voluminous fasciculi which form the entire muscle. The muscle is 

 covered by a connective sheath, called the external perimysium or 

 sarcolemma. The nuclei are flat or oval and can be seen on the 

 inner face of the sarcolemma. 



State the difference in structure between striped muscular tissue and 

 tmstriped muscular tissue. 

 (See answer to preceding question.) Unstriped muscular tissue 

 has no transverse striae and is found in the viscera. It is not under 

 control of the will, hence is called involuntary. Its structure con- 

 sists of fusiform cells, each with a distinct nucleus and bound 

 together by connective tissue. 



Ulustrate the difference between mucous membrane and serous mem- 

 brane as to (a) structure and (b) location. . . 



(a) Both membranes have two layers, the deeper of which are 

 quite analogous. In mucous membrane, the superficial layer may 

 consist of epithelial cells only one layer deep, but usually there 

 are several layers (stratified). Cilia, hair-like appendages, are seen 

 on the surface of mucous membranes in some parts of the body, 

 as well as depressions in the deeper layer, giving rise to follicles and 

 papillae. In serous membranes, the superficial layer always consists 

 of flat polygonal epithelial cells, one layer deep. The free surface 

 is always smooth. 



(b) Mucous membrane is found throughout the inner walls of 

 the alimentary canal, respiratory channels, bladder, urethra and 

 vagina. Serous membrane is found within the thoracic cavity. 



