84 



HUMAN TISSUES 



III. Tear or separate the muscle into parts. Notice that the muscle is 

 divided into little bundles. Try to remove one of the little bundles from the 

 others. Name and describe the tissue that separates one bundle from another. 



Describe the shape of each little 

 bundle. Describe the arrangement 

 of the bundles in making up the en- 

 dmSSHs&fflm tire muscle. 



Problem. The structure of skel- 

 etal muscle. 



Select a tiny muscle bundle ; place 

 it flat on the glass slide and add a 

 drop of dilute iodine. Cover with a 

 cover glass and focus under low 

 power, then high power. 



I. Observe the long individual 

 muscle fibers and find the tiny cross 

 markings called striations. Skeletal 

 muscle is often called striated muscle 

 because of the presence of these char- 

 acteristic cross markings. 



II. Draw two or three muscle 

 fibers five times larger than they 

 appear under the microscope. Label 

 fiber and striations. 



III. Examine a prepared slide of 

 striated muscle. Describe the ap- 

 pearance and location of the nuclei 

 scattered along each fiber. 



'-connective 

 tissue 



. muscle 

 fibers 



A muscle is made of bundles of muscle 

 fibers, each bundle surrounded by connective 

 tissue. A thick external layer of this connec- 

 tive tissue is continuous with the tendon which 

 is composed entirely of connective tissue. 

 The tendon joins the muscle to a bone. 



Problem. The structure of smooth or involuntary muscle. 

 Mount a prepared slide of smooth muscle under the microscope. 



I. How does smooth muscle differ from striated muscle in appearance and 

 shape of fiber and in nuclei ? 



II. Smooth muscle is called smooth or unstriated muscle because of the 

 absence of cross-striations. It is also called involuntary because it is not under 

 the control of the will. It is found in many internal organs such as the walls 

 of the stomach and intestine, and is responsible for movement in these organs. 



III. Draw and label two or three smooth muscle cells. 



