A tissue can be defined as a group of cells with similar structure and embryonic origin working together to perform a particular function in the body.

The four primary tissue types are
1. the EPITHELIAL tissue,
2. the CONNECTIVE tissue,
3. the MUSCLE tissue,
4. and the NERVOUS tissue. Every cell in your body belongs to one of these four tissue types.

   Each of these tissue types is specialized to perform specific functions, and the anatomical characteristics of each are adapted to effectively carry out these functions.

   1. The EPITHELIAL TISSUE covers the body surfaces, lines hollow organs, ventral body cavities and ducts and forms glands.
   2. The CONNECTIVE TISSUE protects and supports the body and its organs, binds organs together, stores energy and provides immunity.
   3. The MUSCLE TISSUE is responsible for movement and the generation of force.
   4. The NERVOUS TISSUE carries information very quickly from one side of the body to the other.

   The main objective of this exercise is to familiarize yourself with the major similarities and differences of the primary tissues and to teach you to recognize the common tissues you will encounter throughout the year. Because epithelia and some types of connective tissue will not be considered in detail again, they are emphasized more than muscle, nervous tissue, bone (a connective tissue) and blood (another connective tissue) which are covered in more depth in later units. You will be looking at many photomicrographs of different tissues. Your prime objective throughout this exercise is to become familiar with the 4 primary tissue types and their subcategories, to learn how to identify them and to describe the relation between structure, function and distribution in the body.