Introduction to Tissues

How would you react if I say that your body is made up of building blocks? I bet you would just laugh it off! If you look at things from a science perspective, then the building blocks that I am talking about are nothing but the cells and tissue. Even plants are made of cells and tissue! Every living organism is made up of cells that form the basic unit of life. Let us know more about these tissues!

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Tissue

Living organisms that are found in the world are classified into unicellular and multicellular organisms. So, if you see unicellular organisms like Amoeba, Paramecium, diatoms, bacteria, etc. have only one cell. They do not have tissue level of organization. Even in some lower order animals, tissue differentiation is absent.

This means that cells form groups. But they do not perform a definite function. But if you see multicellular higher order animals like humans, dogs, etc. different groups of cells perform different specific functions.

If a cell is called the basic unit of life, then a group of cells together make up the tissues. These groups of cells have a common origin with a similar structure. And the groups of cells perform a definite function. So, in simple terms, tissues can be defined as a group of cells performing similar functions.

Tissues represent a level of organization in living organisms. Both plants and animals have tissues. But the kinds of tissues that are present in both the living organisms are different. If you see in animals, groups of muscle cells together form the muscle tissue. Similarly, groups of plant cells form the plant tissue.

(Source Science-resources.co.uk)

Browse more Topics under Tissues

• Meristematic Tissue
• Permanent Tissue
• Epithelial Tissue
• Connective Tissues
• Muscular and Nervous Tissues

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Types of Tissues

Tissues are classified into two types. They are Plant tissues and Animal Tissues.

Plant Tissues

When you see plants and animals, there is quite a bit of difference that is clearly visible. And therefore the internal cell structure of both these organisms also differs. In plants, the tissues that are present have to give structural support to the plant, as plants are stationary.

The pattern of growth that is seen in plants is also limited to certain areas. There are some tissues in plants that divide throughout their life. These are generally restricted to certain regions. Therefore we can aptly differentiate the plant tissues on the basis of the dividing capacity. According to this classification, there are two types of plant tissues. They are :

• Meristematic tissue
• Permanent tissue

Animal Tissues

Animals move from one place to the other in search of food, shelter etc. Therefore the body shows many movements. In order for the body to perform these activities, the cells and tissues perform definite functions.  You can observe that the growth in animals is generally uniform.

Apart from this, in animals, the tissue level organization is very complex, with many organs and organ systems. Each system has specialized tissues performing specialized functions in a synchronized manner. Animal tissues are broadly classified as:

• Epithelial tissues
• Muscular tissues
• Connective Tissues
• Nervous Tissues

Solved Question for You

Q: Do unicellular organisms show a true division of labour?

Ans.  No. Division of labour is absent in unicellular organism, as only one cell performs all the essential functions. Multicellular organisms, which have tissues. exhibit true division of labour.