TISSUES OF THE BODY
Section I. GENERAL
A tissue is a grouping of like cells working together.
2-2. TYPES OF TISSUES
There are several major types of tissues. The most common types are epithelial,
connective, muscle, and nervous tissues. Later, this lesson will discuss each type.
2-3. TISSUES AND ORGANS
a. Tissues make up organs. An organ is a structure performing a particular
function. An organ is composed of several different tissues. Examples of organs are
the lungs and the heart.
b. In some cases, a term may be used to describe both a type of tissue and a
kind of organ. For example, we speak of bone tissue and of bones. We speak of
muscle tissue and of muscles.
Section II. EPITHELIAL TISSUES
Epithelial tissue is tissue that covers surfaces and lines cavities. Here, it may
protect, absorb, and/or secrete. Epithelial tissue covers the outer surface of the body.
It lines the intestines, the lungs, and other hollow organs.
2-5. TYPES OF EPITHELIAL CELLS (BY SHAPE)
Figure 2-1 illustrates the basic types of epithelial cells by shape. The three basic
shapes are squamous (flat), cuboidal (cubes), and columnar (columns).