Cellular Organization of Plants and Animals 47 



Kinds of Animal Tissues (Cont'd) 



MUSCULAR 

 (CONTRAC- 

 TILE) 

 (mus' ku lar) 

 (L. musculum, 

 muscle) (Figs. 

 14 and 15) 



Cells (muscle fibers) are usually elongated and specialized 

 for contraction because of their tendency to shorten when 

 stimulated. Special, internal, contractile fibrillae pro- 

 duced by the cells are responsible for the contraction. 



Functions: Move the body as a whole, or its various parts. 



D. NERVOUS 



(ner' vus) 

 (L. nervus, 

 sinew or fiber) 

 (Figs. 16 and 

 17) 



Highly specialized tissue whose cells (neurons) possess fine 

 cytoplasmic processes (axons and dendrites) to conduct 

 nerve impulses; neurons vary in size and length of their 

 processes; fine neurofibrils in the cytoplasm conduct the 

 impulses in the proper direction; Golgi bodies are par- 

 ticularly visible in neurons; Nissl's granules in the cyto- 

 plasm are probably nutritive as they tend to disappear 

 after prolonged neuron activity. 



Functions: Receive, interpret, and redirect nerve impulses. 



A. Epithelial Tissues (Fig. 11) 



