CLASS 7TH | BIOLOGY | PLANT AND ANIMAL TISSUES | REVISION NOTES

Introduction
Cells are joined to each other to form a secondary level of an organisation called Tissue.
The term ‘Tissue’ was first used by Marie Francois Xavier Bichat in 1792.
Histology: Study of tissue is called Histology.
The tissues are classified as follows on the basis of occurrence in living things:
(1) Animal Tissues
(2) Plant Tissues
Animal tissues: divided into four types on the basis of function

1. Epithelial – work as protective tissues over other tissues. Example: Our skin
2. Connective – hold other tissues or organs. Example: Cartilage
3. Muscular – help in movement and locomotion. Example: Heart muscles
4. Neural or Nervous – responsible for the response against the stimulus with the help of a
   sensory organ like Eyes, ears or tongue.
   Epithelial Tissue: on the basis of cell shape and structure classified as:
   (a) Squamous epithelium or Pavement epithelium
    Has a layer of flat, thin and scale-like cells
    Occurs in alveoli of lung
   (b) Columnar epithelium
    Appears rectangular in vertical view and polygonal in surface view
    Occurs in stomach and intestine
   (c) Cuboidal epithelium
    Cuboidal in shape and with rounded nucleus
   (d) Ciliated epithelium
    Columnar or cubical type cells are present
    Found in respiratory track and uterus

Connective Tissue:
Matrix: embedded cells in intercellular fluids of connective tissue.
On the basis of nature of matrix they are divided as:
(1) Connective tissue proper: soft matrix is present
 Areolar tissue
 Adipose tissue
 Tendon
 Ligament
(2)Fluid connective (Vascular) tissue: has ground matrix (plasma) and specialised free cell.
 Blood
 Corpuscles
(3) Supportive tissue: composed of tough matrix.
 Cartilage
 Bone
Muscular tissue:
These are mainly composed of the cells called myocytes.
On the basis of location, function and structure divided as:
(1) Striated or voluntary muscles
(2) Non-striated or non-voluntary muscles
(3) Cardiac muscles
Neural tissue:
Neurons are the units of nervous tissue.
Neuron is composed of:
 Cyton or cell body
 Dendrons
 The axon
Plant Tissues: Constitute plant body.
Some plant tissues divide throughout their lifespan and some not.
On the basis of development, plant tissues are classified as:
(1) Meristematic
(2) Permanent
Meristematic Tissues:
In initial stage of embryo development in plant, all cells are capable of divisions for plant
growth in length as well as width. These divisible embryonic regions are called meristems.
Meristematic cell can be oval, rectangular, spherical or polygonal in shape.
On the basis of position in plants, they are of three types:
(a) Apical meristems
(b) Intercalary meristems
(c) Lateral meristems
Permanent Tissues: originates from meristematic tissue
On the basis of types of cell divided as:
(i) Simple permanent tissue
(ii) Complex permanent tissue

Simple permanent tissue: contain only one kind of cell
 Parenchyma
 Collenchyma
 Sclerenchyma
Complex permanent tissue: made of more than one kind of cell
 Xylem
 Phloem
Tissue system in Plants
(A) Dermal Tissue system – form outer protective covering of plant
(B) Ground Tissue system – form main bulk of plant
(C) Vascular Tissue system – vascular bundles present in stems and roots
(D) Epidermal Tissue system – it forms outer covering of plant