Tissue Is A Group Of Similar Cells Along With Intercellular Substances Which Perform Specific Function.

        Animal Tissues Are Broadly Classified Into Four Types – Epithelial, Connective, Muscular, Neural.

1.     Epithelial Tissues The Cells Are Tightly Packed In This Tissues And It Provides A Covering or Lining For Some Parts Of The Body. It Is Of Three Types – Simple, Compound, Glandular Epithelium.

        Simple Epithelium It Is Composed Of Single Layer Of Cells And Functions As Lining For Body Cavities, Ducts And Tubes. It Is Divided Into – Simple Squamous, Simple Cuboidal, Simple Columnar, Simple Ciliated Epithelium.

        Simple Squamous Epithelium It Is Made Up A Single Thin Layer Flattened Cells With Irregular Boundaries And Perform Functions Like Forming A Diffusion Boundary.

        Simple Cuboidal Epithelium It Is Composed Of Single Layer Of Cube-Like Cells And Is Involved In Secretion And Absorption.

        Simple Columnar Epithelium It Is Composed Of Tall And Slender Cells In A Single Layer. It Helps In Secretion And Absorption

        Simple Ciliated Epithelium If Columnar or Cuboidal Cells Bear Cilia On Their Free Surface They Are Called Ciliated Epithelium. They Help In Movement Of Particles Or Mucus In A Specific Direction.

        Compound Epithelium This Kind Of Epithelium Is Made Up Of More Than One Layer Of Cells. Its Main Function Is To Provide Protection Against Chemical And Mechanical Stress.

        Glandular Epithelium When Columnar Or Cuboidal Cells Are Specialised For Secretion They Are Called Glandular Epithelium They Are Of Two Types – 1. Unicellular, e.g. Goblet Cells 2. Multicellular, e.g. Salivary Gland

        Cell Junctions The Cells In Epithelium Are Held Together With The Help Of Specialised Junctions Which Provide Both Structural And Functional Link, They Are Called Cell Junction. Three Types Of Cell Junctions Are Present In Epithelium – Tight Junctions, Adhering Junctions, Gap Junctions.

2.     Connective Tissues These Are The Most Abundant Tissue And Help In Linking And Supporting Tissues/Organs Of The Body. They Are Of Following Types – Loose Connective Tissue, Dense Connective Tissue, Skeletal Tissues.

        Loose Connective Tissues The Cells And Fibres Are Loosely Arranged In A Semi-Fluid Ground Substance. Its Main Type Are – Areolar Tissue, Adipose Tissue.

        Areolar Tissue It Is Made Up Of Fibroblasts And Present Beneath The Skin And Serves As A Support Framework For Epithelium.

        Adipose Tissue It Is Made Up Of Adipocytes And Is Specialised To Store Fats.

        Dense Connective Tissue The Cells And Fibres Are Compactly Packed To Form A Regular Or Irregular Pattern.

        Dense Regular Connective Tissue In These Types Of Tissue Collagen Fibres Are Present In Rows Between Many Parallel Bundles Of Fibres, e.g. Tendons.

        Dense Irregular Connective Tissue In These Types Of Tissues Fibres Are Oriented Differently, e.g. Skin.

        Skeletal Connective Tissue It Includes Cartilage, Bone And Blood.

        Cartilage It Is Made Up Of Chondrocytes Enclosed In Small Cavities. Its Intracellular Material Is Solid, Pliable And Resits Compression. It Provides Support And Flexibility To The Body Parts.

        Bone It Is Made Up Of Calcium Salts And Collagen Fibres In A Hard And Non-Pliable Ground Substances. It Provides Structural Frame To The Body And Protect Softer Tissues And Organs.

        Blood It Is Fluid Connective Tissue Which Help In Transportation Of Various Substance. Its Constituents Are RBCs, WBCs And Platelets.

3.     Muscle Tissue This Tissue Helps In The Movement Of The Body. Muscle Cells Are, Made up Of Myofibrils Which Contract And Relax In Response To Stimulus And Help In Movement. The Three Types Of Muscle Tissue Are – Skeletal Muscles, Smooth Muscles, Cardiac Muscles.

        Skeletal Muscles They Are Closely Attached To Skeletal Bone And Bundled Together In Parallel Fashion, It Shows Striations.

        Smooth Muscles They Are Held Together By Cell Junctions And Bundled Together To Form Connective Tissue Sheath. It Doesn’t Show Striation.

        Cardiac Muscle Tissue It Is Present Only In Heart. Communication Junction Allow The Cells To Contract As A Unit.

4.     Neural Tissue It Is made Up Of Nerve Cells or Neurons. Nervous Tissue Exerts Greatest Control Over The Response Of Body As They Have The Property Of Excitability And Conductivity.

        Neuron Or Nerve Cell Is Made Up Of Axon, Cell Body Dendrites.

        Synapse Is A Junction Between Axon Endings Of One Nerve Fibre And Dendrite Of The Other.

        Neuroglial Cells Are The Supporting Cells Found In Brain And Spinal Cord To Support Neurons 50% Of Brains Cells Are Neuroglial Cells.


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