Animal Tissues

Based on their functions, animal tissues can be classified as:

  1. Epithelial Tissue
  2. Connective Tissue
  3. Muscular Tissue
  4. Nervous Tissue

Epithelial Tissues:

  • They are the covering or protective tissues in the animal body.
  • It covers most of the organs and cavities in the animal body.
  • It also forms a barrier to keep the organs separate.
  • The skin, the lining of mouth, the lining of blood vessels, lung alveoli and kidney tubules are made up of epithelial tissues.
  • They are tightly packed with almost no intercellular space between them.

Based on their functions, different epithelia show different structures. They can be classified as:

  1. Simple squamous epithelium – It is a simple flat kind of epithelium. It is found in cells lining blood vessels, lungs alveoli, lining of mouth and oesophagus.
  2. Stratified squamous epithelium – They are arranged in a pattern of layers to prevent wear and tear. They are found in the skin.
  3. Columnar epithelium – It is tall, pillar-like epithelium. It is present in the inner lining of intestines.
  4. Ciliated Columnar Epithelium – Some columnar epithelial tissues have hair like structures called cilia. The movement of cilia can move mucus.
  5. Cuboidal Epithelium – It has cube shaped cells. It forms the lining of kidney tubules and ducts of salivary glands.
  6. Glandular Epithelium – Sometimes, a portion of the epithelium tissue folds inward, and a multicellular gland is formed. This is known as ‘Glandular Epithelium’.

Connective Tissue:

  • The cells are loosely packed and embedded in an intercellular matrix.
  • The matrix can be jelly like, fluid, dense or rigid.
  • The nature of matrix depends on the function of that particular connective tissue.

Connective Tissues can be classified as:

  1. Blood – It has a fluid matrix called plasma. Plasma contains salts, proteins and hormones.
  2. Bone – It is strong and non-flexible. The cells are embedded in a hard matrix made up of calcium and phosphorous.
  3. Ligament – It is elastic and has considerable strength. It contains very little matrix.
  4. Tendons – It is fibrous tissue with great strength but limited flexibility.
  5. Cartilage – It is a solid matrix composed of proteins and sugars.
  6. Areolar connective tissue – It fills the space inside the organs, supports internal organs and helps in repair of tissues.
  7. Adipose tissue – The cells are filled with fat globules.

Muscular Tissue:

  • It consists of elongated cells called muscle fibres.
  • Muscles contain special proteins called contractile proteins, which contract and relax to cause movement.

Types of Muscular Tissues:

  1. Striated Muscles – The cells are long, cylindrical, unbranched and multinucleate. They are also called voluntary muscles or skeletal muscles.
  2. Unstriated Muscles – The cells are long with pointed ends and uninucleate. They are found in iris, ureters, bronchi of the lungs, etc.
  3. Cardiac Muscles – These are found in heart. These heart muscles are cylindrical, branched and uninucleate.

Nervous Tissues:

  • The cells of these tissues are called nerve cells or neurons.
  • A neuron consists of nucleus and cytoplasm.
  • Each neuron has a single, long part called axon and many branched parts are called dendrites.
  • The brain, spinal cord and nerves are composed of nervous tissues.
  • They are specialised in responding to stimuli.

Published by Priya Prakash

In the midst of winter, i found there was within me an invincible summer ~ Albert Camus

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