Classification of Tissues

All living organisms are made up of tiny building blocks called cells, which are the smallest units of life. These cells combine to form tissues, which further unite to form organs and organ systems. So, what is a tissue in science?

All biotic organisms in the world are classified into two major categories: unicellular and multicellular organisms.

In higher multicellular organisms such as dogs and human beings, cells cluster together to form groups that perform a particular function. Each group performs a specific function and is known as a tissue.

To put it simply, a tissue is a group of cells that play a similar role. These are present in both plants and animals and represent levels of organisation in living organisms. 

The study of tissues is called histology, and for plants, the subject is called plant anatomy.

Read on to know more about tissue and its types.

Classification of Tissues

Tissues form an intermediate organisational structure between cells and the organ systems. Different groups of tissues with diverse functions group together to form an organ. In animals, therefore, a group of muscle cells combine together to form muscle tissue.

The classification of tissues in animals falls under four major categories. These are:

  • Connective tissues.

  • Muscle tissues.

  • Nervous tissues.

  • Epithelial tissues.

Before you learn more about what is the function of tissue, here’s a quiz for you to try:

Pop Quiz 1:

  1. The study of tissues is known as ________.

  1. Plant anatomy.

  2. Morphology.

  3. Histology.

  4. Natural history.

Connective Tissues

In connective tissue, a group of cells separated by a non-living extracellular matrix combine to form a tissue. Connective tissues help provide mechanical strength, shape and rigidity to the organs and keep them in place. Examples of connective tissues include tendons, ligaments, bones, blood, adipose and areolar tissues. Further, there are three types of connective tissues. These are:

  • Skeletal Connective Tissue.

  • Fluid Connective Tissue.

  • Fibrous Connective Tissue.

Connective tissues have several different functions in the human body, namely:

  1. They provide insulation and protection against cold to the body.

  2. They help bind the organs together and provide mechanical support to them.

  3. Connective tissues help transport gases, water, hormones, nutrients and waste materials within the body.

Muscle Tissue

Muscle tissues help us to perform different actions and engage in activities like walking, running and locomotion. There are three types of muscle tissue:

  • Skeletal muscles.

  • Cardiac muscles.

  • Visceral or smooth muscles that line the inner walls of organs.

Firstly, muscle tissues help us to maintain our posture. Secondly, they also aid in our involuntary and voluntary movements. For example, cardiac muscles help pump blood and regulate its flow in arteries and capillaries. 

Nervous Tissue

Nervous tissues are present in the central nervous system that comprises the brain and spinal cord. In the peripheral nervous system, nervous tissues make up the cranial and spinal nerves.

Nervous tissues perform several vital functions, such as:

  • They control and coordinate metabolic activities in the body.

  • They help transmit information within the body.

  • They help maintain stability and create an acute awareness of the environment around us.

  • They also help us respond to external stimuli.

Epithelial Tissue

Epithelial tissues consist of cells that form the external covering of the body. These covers the organ surfaces such as the skin, the airways, the inner walls of our digestive tract as well as the reproductive tract. 

Epithelial tissues provide support and mechanical strength to the cells and tissues. They also help in the transportation of materials through diffusion, secretion and filtration.

Moreover, epithelial tissues such as the ones beneath our skin help us in sensory reception and protect us against pathogens and physical trauma. They also secrete hormones, mucus and enzymes from various endocrine organs.

Now that you have gone through the classification of tissues, it’s time to revise a few concepts with the following exercise.

Pop Quiz 2

  1. What are the types of tissues?

  1. Connective Tissues.

  2. Nervous Tissue.

  3. Epithelial Tissue.

  4. Muscle Tissue.

  5. All of the above.

Here is a classification of tissues chart to help you understand better.

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FAQ (Frequently Asked Questions)

1. How many Types of Tissues are There?

Ans. There are four types of tissues in animals. These are the connective tissues, the muscle tissues, the nervous tissues and the epithelial tissues.

2. What is the Definition of Tissue?

Ans. A group of cells that play a similar role is called a tissue. In higher multicellular organisms such as human beings, cells cluster together to form groups that perform a definite function. Each group has a specific purpose and is known as a tissue.

3. Write Down two Functions of Connective Tissues.

Ans. Connective tissues help provide mechanical strength, shape and rigidity to the organs and keep them in place. They provide insulation and protection against cold to the body.