Two hundred kinds of cell
The plant half of this chapter dealt with five tissues. The animal half deals with four — out of a body built from more than two hundred different kinds of cell.
The number
Like a plant body, an animal body is built up from a great many different kinds of cell joined together. About 210 different cell types take part in building the human body.
Animal tissue
In a multicellular animal body too there are groups of cells with a common origin, shaped to carry out a definite function. These are animal tissues. It is the same definition as for plants, word for word.
Two hundred cell types, four tissue types
The numbers do not match because a tissue type is a grouping, not a cell. Dozens of different cell types are all epithelial, in different shapes and different numbers of layers, because they all line a surface. Classifying by what the tissue does is what turns two hundred into four.
Classified by function, not by position
Plant tissues were classified by whether their cells could still divide. Animal tissues are classified by what they do. In the body of a vertebrate, four main tissue types are recognised on that basis, and the rest of this chapter takes them one at a time.
You have already followed one cell all the way up
In grade 10 you traced a cardiac muscle cell into cardiac muscle tissue, into the heart, into the circulatory system, into a human being. That was one worked example of a chain. This half of the chapter fills in the second link of it — properly, for all four kinds.