Tissue is a group of cells that work together to perform a specific function. There are four main types of tissues in animals - epithelial, connective, muscular and nervous tissue. Epithelial tissue covers external and internal surfaces. Connective tissue connects, supports or binds other tissues. Muscular tissue allows for body movement via contraction. Nervous tissue conducts electrical signals throughout the body to coordinate responses.

2. Tissue is a cellular organizational
level intermediate between cells and
a complete organism. Hence, a tissue
is an ensemble of cells, not necessarily
identical, but from the same
origin, that together carry out a
specific function.

3. The study of tissue is
known as histology or, in
connection with
disease, histopathology.

4. Plant tissues Animal Tissues
Since plants are stationary so they Since animals are mobile so they
do not require much energy, Hence require more energy, hence more
more living tissues are not required. living tissues are required.
In plants, most tissues provide Animals move from one place to
structural strength. Most of these another in search of food, shelter
tissues are dead etc., hence they need more energy
9can provide mechanical strength as and there more tissues are living.
easily as the living ones and need
less maintenance.
Growth is limited to certain regions Cell growth is uniformally distributed
Structural organisation of organs is Structural organisation of organs and
comparatively less complex. organ systems is more specialised
and complex.

5. Plant Tissues
Permanent Tissues
Meristimatic Tissues (Cells with speciallised structure and function that have lost their
(These cells continuously divide throughout the life of the plant) ability to divide further)
Simple Permanent Tissue
Apical Meristem Complex Permanent Tissue
Parenchyma
Xylem
Lateral Meristem
Collenchyma
Phloem
Intercalary
Meristem
Sclerenchyma

6. Meristematic tissue: Cells of this tissue continue to divide
throughout the life of the plant. Some of these cells lose their
ability to divide and become part of other tissues.
Name of the Location Function
tissue
Apical Meristem Present at the growing tip of stem Increase in length of stem
and root and root
Lateral Meristem Found on the lateral sides of Increase in girth of stem
(also called roots and stem and root
cambium)
Intercalary Present at the base of leaves or Growth of leaves and
Meristem internodes branches

8. A longitudinal section through a growing shoot tip showing apical
meristematic tissue. Note that the cells are small, have dense
cytoplasm, and are very tightly packed.

9. High power view of a longitudinal
section of the Coleus apical
meristem. The apical meristem is a
dome-shaped mass of dividing cells
at the tip of the shoot. The apical
meristem will produce the three
primary meristems:
protoderm, procambium, and
ground meristem. These three
meristems in turn will produce new
cells that will differentiate into the
epidermis, primary vascular
tissues, and ground tissues (pith
and cortex).

10. A longitudinal section through a root tip. The meristematic tissue is
located just above the root cap. This too is apical meristem; division
of these cells followed by cell elongation results in the root growing
in length.

11. It is a cross section of a dicot
stem.
Focus on the two large
vascular bundles in the center
of the slide.
The xylem tissue is stained
red.
Just above the xylem is a
layer of meristematic
tissue, the vascular cambium.
The phloem tissue is found
outside of the vascular
cambium.

12. This is a high-power view of a cross-section showing a lateral meristem, the vascular cambium, in the
same plant shown in previous slide. Again, the xylem tissue is stained red, and the large cells on the top
of the slide are phloem. The green brick-like cells between the xylem and phloem is the area in which
the vascular cambium is located. The new cells produced by the cambium are initially like those of the
cambium itself, but, as they grow and mature, their characteristics slowly change as they differentiate
into other tissues. The vascular cambium is a single layer of cells within this brick like region; it is
responsible for the growth in diameter of a stem. The tissues produced by the vascular cambium are
secondary tissues.

13. Permanent tissue: Cells of this tissue have lost their ability to
divide and they have a specialized structure to perform
specific functions.
Based on the type of cells present in the tissue, the
Permanent tissue is divided into two categories:
Simple Permanent Tissue
and
Complex Permanent Tissue.
While the simple permanent tissue consist of only one type
of cells (eg. Parenchyma),
the complex permanent tissue consists of more than one
type of cells (eg. Xylem and phloem)

14. S i m p l e P e r m a n e n t T i s s u e s
Parenchyma
Structure:It is the fundamental tissue composed of thin walled, living
cells whose cell wall is composed of cellulose. Small intercellular spaces
are present between the cells.
Location and function: It occurs in all soft parts of plants and is
meant for storage of food and to provide turgidity to softer parts of plants.
Parenchyma tissue in stem and roots store nutrients and water.
Types of parenchyma:
i) Chlorenchyma :Certain parenchymatous tissue contain chloroplast
and synthesize food by the process of photosynthesis.
ii) Aerenchyma: In aquatic plants parenchymatous cells have air cavities
between them to store air, such a tissue is called Aerenchyma. It provides
buoyancy to the aquatic plants so that they can float in water.

16. Collenchyma
Structure: This tissue is composed of somewhat elongated cells with
cell walls that are irregularly thickened at corners due to deposition of
cellulose or pectin. They may be oval, circular or polygonal. Very little
intercellular spaces are present.
Location: It occurs below the epidermis of stem and petiole (stalk of
the leaf) and around veins.
Function: This tissue provides mechanical support and flexibility and
in some cases it may possess chloroplasts to perform Photosynthesis.
The stem and leaves are able to bend easily and then come back to
their original position due to the presence of collenchyma.

17. Collenchyma in Transverse Section Showing
Wall Thickenings
1. Cell Wall
2. Wall Thickenings
3. Protoplasm
4. Vacuole

18. Sclerenchyma
Structure: It is a tissue of dead and thick walled cells, having no
intercellular spaces. The thickenings are of cellulose or lignin or both.
Several unlignified areas called pits often develop on walls.
Location: This tissue is usually found in the hard and stiff parts of the
plant like seed coat, husk of coconut, in the stem around vascular
bundles, veins of leaves and hard covering of fruits and nuts.
Function: It is the chief mechanical tissue in plants and is able to bear
push, pull, strain and shearing forces. It provides strength to plant
parts and also protects the delicate parts of the plants.
They are of two types: fibres and sclereids.

19. Sclerenchyma

22. Epidermis and Bark
The protective tissues
The epidermis usually consists of a single-layered group of cells that covers
plants leaves, flowers, roots and stems. It forms a boundary between the plant
and the external world.
Bark is formed from the meristem that appears later in the life cycle of a plant.
Woody stems and some other stem structures produce a secondary covering
called the secondary meristem or periderm or cork cambium that replaces the
epidermis as the protective covering.
The periderm replaces the epidermis, and acts as a protective covering like the
epidermis.
Cells produced on the outside by periderm form the cork. Cells of have suberin
in their walls to protect the stem from drying and pathogen attack. Older cork
cells are dead, as is the case with woody stems. As the stem grows, the cork
cambium produces new layers of cork which are impermeable to gases and
water.

25. A high-power view of one glandular hair. Secretory hairs may
provide a chemical defense against insects.

27. Another type of surface tissue, the outer bark or periderm (stained red in this slide).
Periderm is found on the surface of woody plants; it includes the cork cells on the
surface of older woody stems. The periderm replaces the epidermis in plants that have
secondary growth. The cork cells are dead; it is their waterproofed cell walls that
function as the protective outer covering of plants. Meristematic cells within the
periderm (cork cambium, the other lateral meristem) produce the cork cells.

28. Complex Permanent Tissues
Xylem and Phloem

29. Xylem
It is a complex permanent
tissue, which is specialized
for the conduction of water
and mineral substances in
the plant body. Xylem is a
heterogenous tissue made
up of four different types of
cellular elements.
They are:
•Xylem tracheids
•Xylem tracheae or vessels
•Xylem fibers and
•Xylem parenchyma

30. Phloem:
Phloem is a complex
permanent tissue, which is
specialized for the
conduction of food and
other organic substances.
Phloem is also a
heterogenous tissue, made
up of four different types of
cellular elements, namely,
•Sieve tubes
•Companion cells
•Phloem parenchyma and
•Phloem fibres

32. Multicellular (large) organisms function more efficiently if
cells become specialized for specific functions.
There are four types of tissues found in animals: epithelial,
connective, nerve, and muscle tissue.
Sponges do not have tissues.

36. Epithelial tissue
Epithelial tissue covers the
whole surface of the body. It is
made up of cells that are
closely packed and are
composed of one or more
layers. This tissue is
specialised to form the
covering or lining of all internal
and external body surfaces.
Epithelial tissue that occurs on
surfaces on the interior of the
body is known as
endothelium.
Cellular arrangements in epithelial tissues.
(a) Squamous. (b) Cuboidal. (c) Columnar. (d)
Stratified squamous. (e) Pseudostratified. (f)
Transitional.

38. Types of Epithelial Tissue
Name of Structure Location Function
the Tissue
Simple Squamous cells have the appearance of thin, flat They form the lining of cavities such Protection and transportation of
Squamous plates.The nucleus is flat and elliptical. as the mouth, oesophagus, blood substances through a selectively
Epithelium vessels, heart and lungs permeable surface.
Simple Cells are arranged in many layers and the top layers of The mammalian skin is an example of Protection and to prevent wear
Stratified this tissue may consist of dead cells that are covered dry, keratinised, stratified and tear
Epithelium with keratin (a protein) epithelium.
Cuboidal cuboidal cells are roughly square or cuboidal in shape. Cuboidal epithelium is found in Protection and mechanical support
Epithelium Each cell has a spherical nucleus in the centre glands and in the lining of the kidney
tubules as well as in the ducts of the
glands. They also constitute the
germinal epithelium which produces
the egg cells in the female ovary and
the sperm cells in the male testes.
Columnar Cells occur in one or more layers. The cells are elongated and Columnar epithelium forms the lining Protection, absorption of food (in
Epithelium column-shaped. The nuclei are elongated and are usually of the stomach and intestines. Some small intestine), secretion of
located near the base of the cells. columnar cells are specialised for enzymes
sensory reception such as in the
nose, ears and the taste buds of the
tongue.
Ciliated simple columnar epithelial cells, but in addition, they Ciliated epithelium is usually found in This movement of the cilia in a
Columnar posses fine hair-like outgrowths, cilia on their free the air passages like the nose. It is certain direction causes the mucus,
Epithelium surfaces. These cilia are capable of rapid, rhythmic, also found in the uterus and to move (flow or stream) in that
wavelike beatings in a certain direction. Fallopian tubes of females. direction. The movement of the
cilia propel the ovum to the uterus.
Glandular Columnar epithelium with goblet cells is called Inner lining of stomach and salivary specialised gland cells are capable
Epithelium glandular epithelium. Some parts of the glandular glands of synthesising and secreting
epithelium consist of such a large number of goblet certain substances such as
cells that there are only a few normal epithelial cells enzymes, hormones, milk, mucus,
left. sweat, wax and saliva.

39. Connective Tissue
It is an animal tissue that is characterized by the abundance of
extracellular components (such as fibers and intercellular substances).
The tissue derives its name from its function in connecting, supporting,
surrounding or binding cells and tissues.
Connective tissue is composed of:
•cells
•extracellular matrix
Extracellular matrix is a special feature that distinguishes connective
tissue from the other tissues of the body. This matrix may be jelly-like,
fluid, dense or rigid. The nature of matrix differs according to the
function of that particular connective tissue.

42. Muscular tissue
Muscles of the body are made up of elongated muscle cells also
known as muscle fibre. The movement of the body is brought
about by the contraction and relaxation of contractile protein
present in muscle cells. These contractile proteins are actin and
myosin.

47. Nervous Tissue
All living cells have the ability to
react to stimuli. Nervous tissue
is specialised to react to stimuli
and to conduct impulses to
various organs in the body
which bring about a response to
the stimulus. Nerve tissue (as in
the brain, spinal cord and
peripheral nerves that branch
throughout the body) are all
made up of specialised nerve
cells called neurons.

48. Neurons have many different shapes and
sizes. However, a typical neuron in a human
consists of four major regions: a cell
body, dendrites, an axon, and synaptic
terminals. Like all cells, the entire neuron is
surrounded by a cell membrane. The cell
body is the enlarged portion of a neuron that
most closely resembles other cells. It
contains the nucleus and other organelles
(for example, the mitochondria and
endoplasmic reticulum). The dendrites and
axon are thin cytoplasmic extensions of the
neuron. The dendrites, which branch out in
treelike fashion from the cell body, are
specialized to receive signals and transmit
them toward the cell body. The single long
axon carries signals away from the cell body.
In humans, a single axon may be as long as
1 meter (about 3 feet). Some neurons that
have cell bodies in the spinal cord have
axons that extend all the way down to the
toes.

50. A nerve is an
enclosed, cable-like
bundle of axons (the
long, slender projections
of neurons). A nerve
provides a common
pathway for the
electrochemical nerve
impulses that are
transmitted along each
of the axons.

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