Tissues
Multicellular organisms are made up of million numbers of cells. Most of
the cells are specialised to carry out some specific or special function.
Many cells groups together for a very specialised need and they perform a
particular function. These cluster of cells are called as tissue which is
arranged and designed in such away so as to give the highest possible
efficiency of function.
Plant tissue
Meristematic tissue
The growth of plant occurs only in certain specific region. This happens
due to the dividing tissues called the meristematic tissues located only at
this point. New cells produced by Meristem are like Meristem itself, but as
they grow and mature the characteristic slowly changes and become different
as component of other tissues.
The girth of the stem or root increases due to Lateral Meristem (cambium).
Intercalary Meristem are present in the base of leaves or internodes on
twigs.
Permanent tissue
When meristematic tissue takes up a specific role and lose the ability to
divide they form a permanent tissue. This process of taking a permanent
shape size and function is called differentiation.
Chlorenchyma
This type of permanent tissue consists of specialised cell with thin cell
walls. It provides support to the plant and also store foods. It contains
chlorophyll and perform photosynthesis and are called as chlorenchyma.
Aerenchyma
In aquatic plants large air cavities are present in parenchyma to give
buoyancy to the plant to help them float. Such type of parenchyma are
called as aerenchyma.
Chollenchyma
A type of permanent tissue that gives the property of flexibility. It
allows easy bending in various part of plant without breaking. The cells of
this tissue are living elongated and irregularly thickened at the corners.
Sclerenchyma
A Type of permanent tissue which makes the plant hard and stiff. As we have
seen in the husk of a coconut it is made up of sclerenchymatous tissue. The
cells of this tissue are dead. they are long and have narrow walls are due
to lignin.
Epidermis
The outermost layer of the cells of permanent tissues are called as
epidermis. Epidermis is made up of single layer of cell. Epidermis living
in very dry habitats are very thick since protection against water loss is
needed.
Epidermal cell of the roots whose function is water absorption, commonly
bears long hair like parts that greatly increases the total absorptive
surface area.
Complex permanent tissue
Complex permanent tissues are made up of more than one type of cell. All
these cells co-ordinate to perform a common function. Xylem and phloem are
examples of complex tissue.
Xylem
Xylem consists of tracheids, vessel xylem, parenchyma and xylem fibres. The
cells have thick walls and many of them are dead cells. Xylem allows
transportation of water and Minerals vertically. The parenchyma stores food
and help in sideways conduction of water.
Phloem
It consists of four type of elements sieve tubes, companion cell, phloem
fibres and phloem parenchyma. Phloem is not like xylem, materials can flow
in both direction in phloem. phloem transport food from leaves to other
parts of the plants. Except phloem fibre phloem cells are living cells.
Animal tissue
Epithelial tissue
Covering or protective tissue in animal body are epithelial tissue, it
covers most organs and cavity within the body.
The skin, Lining of our mouth. the lining of blood vessels, lungs alveoli
and kidney tubules are made up of epithelial tissue.
Permeability of the cells of various epithelial tissue plays a very
important role in regulating the exchange of material between the body and
external environment and also between different parts of the body.
Squamous epithelium
Transportation of substances occurs through a selectively permeable
surface, this is simple flat kind of epithelium and is called as squamous
epithelium. The esophagus and the lining of the mouth are covered with
squamous epithelium.
Skin epithelial cells are arranged in many layers to prevent wear and tear.
These pattern of layers in epithelium is called as stratified squamous epithelium.
Columnar epithelial tissue
Where absorption and secretion occur like in small intestine epithelial
tissues are present and are called as columnar epithelial tissue.
This type of tissue Contains hair like projections on the outer surface of
the tissue called Cilia.
Cuboidal Epithelium
Type of epithelial tissues that from the lining of kidney tubules and duct
of saliva gland where it provides mechanical support.
Glandular epithelium
Epithelial cells often acquires additional specialisation as gland cells in
the epithelial surface. In this a portion of the epithelial tissue folds
inward and a multicellular gland is formed.
Connective tissue
Blood is a type of connective tissue. These tissues are called connective
tissue because they are closely spaced and embedded in an intercellular
Matrix. The Matrix can be Jelly like fluid, dense or rigid. The fluid
Matrix in which blood is present is called as plasma in which red blood
cell (RBC) white blood cell (WBC) and platelets are suspended.
Bones are another kind of connective tissue it forms the framework and
supports the body. It also anchors the muscle and support the main organs
of the body. Tt is strong and non-flexible tissue.
Ligament
two bones are connected to each other by a different type of connective
tissue called the ligament. These tissues are very elastic and have a
considerable strength.
Tendons
Bones and muscles are connected by a different type of connective tissue
called tendon. These are fibrous tissue with great strength but limited
flexibility.
Cartilage
It is a type of connective tissue which has widely spaced cells, the solid
matrix in the cartilage is composed of proteins and sugar. Cartilage
smoothens bone surface at joints and is also present in nose, ear, trachea
and larynx.
Areolar connective tissue
It is present between the skin and muscles, around blood vessels and nerves
and in the bone marrow. It fills the space inside the organs, support
internal organs and help in repair of tissues.
Muscular tissue
Muscular tissue consists of elongated cells also called muscle fibres, it
contains special protein called contractile protein which contracts and
relax to cause movement. it is responsible for the movement of our body.
Voluntary muscles
Some muscles can be controlled consciously, these are present in our limbs.
We can decide to start and stop of the movement of this muscles. Such
muscles are called as voluntary muscles they are also called as skeletal
muscle as they are mostly attached to bones and help in body movement.
These muscles show light and dark bands when stained appropriately as a
result they are also called striated muscles.
Involuntary muscles
The movement of the food in the alimentary canal, contraction and
relaxation of blood vessels are unconscious movements and these movements
are performed by a certain kind of muscles called involuntary muscles.
These muscles are found in the Iris of the eye, the ureter and in the
bronchi of the lungs. They are also called as unstriated muscles.
The muscle involved in the movement of our heart are called as cardiac
muscles. Heart muscle cells are cylindrical, branched and uninucleate.
Nervous tissue
In this kind of tissue all the cells are responsible for the ability to
respond to stimuli. These are highly specialised tissue for being
stimulated and then transmitting the stimulus very rapidly from one place
to another within the body. the cells of these tissues are called nerve
cells or neurons. the neuron consists of a cell body with a nucleus and
cytoplasm from which long thin hair like parts arise. new Rose has a single
long part called axon and many short branches called dendrites.