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TISSUES OF THE BODY
Tissues are formed from the assemblage of cells and intercellular materials in various
proportions in which one component predominates. In nervous tissue as an example, nerve
cells predominate while in connective tissues such as Ligaments and Tendons, intercellular
fibrous materials predominate. A tissue could therefore be described as comprising cells,
which share structural and functional similarities and intercellular materials.
In the course of development of the body, cells undergo specialization following which they
aggregate, based on functional and structural similarities to form body tissues. This
arrangement is responsible for the high level of organization and distribution of labor in the
body.
When tissues are assembled in various proportions to form a functional entity, an Organ is
said to be formed.
The organization of tissues within an organ determines the structure as well as the functional
capabilities of the organ.
There are four main types of tissues within the human body. These are commonly referred to
as the Primary (Basic) tissues of the body. The basic tissues of the body include:
• Epithelial (Covering) Tissue (See Diagram EP 1):
Epithelial tissue covers the external and internal surfaces, including cavities and tubes of the
body. Three different shapes of cells are encountered in the epithelium. These are:
1. Squamous (Flat) cells
2. Cuboidal cells and
3. Columnar cells.
These three cell types could be arranged in:
• A single layer to form Simple epithelium e.g. the lining of the stomach (columnar
epithelium) or in
• Several layers to form a Compound (Stratified) epithelium e.g. the epidermis of the
skin (squamous epithelium)
• Connective Tissue: This tissue connects cells and other tissues of the body,
offering structural and metabolic support. It also serves as a medium of conveying
nutrients to and removing waste from tissues and body organs. It is composed of
specialized cells (Fibroblasts), intercellular fibrous materials (Collagen, Reticular and
Elastic fibres) and an extracellular fluid medium called Matrix (Ground substance).
The connective tissue is the most abundant tissue in the body.
Examples of Connective tissues are:
1. Bones
2. Cartilage
3. Ligaments, tendons and facial sheath
4. Areola tissue
5. Adipose (Fat) tissue
6. Blood
7. Mucous
