FOR STUDENT'S

1. TISSUES
BY
CYNTHIA DIAS
TSPS, EKM

2. PLANT TISSUES

4. • Since the function of cells are taken up by
different group of cells, we can say that there is
division of labour in multicellular organisms.
• A group of cells that are similar in structure and
work together to achieve a particular function
forms a tissue
• Plants and animals are made up of different
types of tissues
• The term tissue was coined by the scientist
Bichat in 1792, and the study of tissues is called
Histology.
• He is known as the father of histology.

5. THE IMPORTANCE OF TISSUES
• Formation of tissues has brought about a division of
labour in multicelluar organisms
• Tissues become organised to form organs and organs
into organ systems
• As a result of improved organisation and higher
efficiency multicellular organisms have higher
survival
• Plants are autotrophic organisms, so prepare their
own food by photosynthesis, they are stationary and
do not move from place to place, hence they do not
need much energy. Most of the tissues in plants are
dead and provide structural strength.

6. • Animals on the other hand are heterotrophic
organisms, they move in search of food and
hence need more energy compared to
plants, most of the tissues they have are living.
• Hence the plants and animals are made of
different types of tissues.
• There are some tissues in plants which divide
through out their life, they divide for the growth
and reproduction of the plant
• Such ever dividing tissues are localised in certain
regions of the plant body, thus based on the
dividing capacity of the tissues they are classified
into two

8. MERISTEMATIC TISSUES
• They divide continuously and help in increasing
the length and girth of the plant
• They are similar in structure and have thin
cellulose cell walls
• They are spherical or isodiametric in shape
• They are compactly arranged and no intercellular
spaces between them
• They have few vacuoles or no vacuoles at all
• They are found in the growing regions of the
plant, according to their positions, meristems are
apical, lateral and intercallary

10. APICAL MERISTEMS
• They are situated at the growing tip of the stems
and roots, i.e., at shoot apex and root apex
LATERAL MERISTEMS
• They are found beneath the bark and in vascular
bundles of dicot roots and stems. Cambium is
the region which is responsible for growth in
thickness.
INTERCALLARY MERISTEMS
• They are located at the base of the leaves or
internode , e.g., stems of grasses and other
monocots

11. PERMANENT TISSUE
• Cells derived from division of meristematic tissue
take up specific role and lose the ability to divide
thus forming a type of permanent tissue.
• The developmental process by which cells
derived from meristematic tissue, take up a
permanent shape, size and function is called
differentiation
• The permanent tissue is divided into two
The simple permanent tissue and
The complex permanent tissue

12. SIMPLE PERMANENT TISSUE
• They are composed of cells which are structurally
and functionally similar
1. PARENCHYMA
• It forms the bulk of the plant body
• They are living and possess the power of division
• The cells are rounded or isodiametric in shape
• The cell wall is thin and can be said to be having
living protoplasm.
• Intercellular spaces are abundant
• It is widely distributed in plant bodies such as
stems, roots, flowers and fruits

15. • If chlorophyll is present it is called
chlorenchyma, it performs photosynthesis
• in aquatic plants large air cavities are present in
the parenchyma to give buoyancy to the
plant, such type of parenchyma is called
aerenchyma
 Collenchyma
• are a type of parenchyma cells, which are living
but is charecterised by the depositon of extra
cellulose at the corners of the cells .
• In collenchyma intercellular spaces are absent, at
times chlorophyll is present in them

16. Functions
• It is a mechanical tissue and hence provides
mechanical support and elasticity
• Thus it provides flexibility to the organs where
they are found

17. Aerenchyma

18. SCLERENCHYMA
• These are dead cells devoid of protoplasm
• The cell walls are thickened of lignin , such cell
walls are lignified
• The cells are closely packed with no intercellular
spaces
• The cells of sclerenchyma are of two types
Fibres and
sclerids

20. Fibres
• The fibres consist of very narrow, thick and lignified
cells
• The fibres are usually pointed at both ends and are
clustered into strands

21. Sclereids
• In contrast to fibres the sclereids are called the stone
cells or the grit cells, which are dead cells
• The sclerenchyma occur in patches or in layers
• They are found in the stems, roots, veins of leaves, hard
covering of seeds and nuts
• Sclereids form the gritty part of most of the ripe fruits
and contributes to the hardness to the seed coat and
nutshell
• The husk of coconut is sclerenchymatous.
Functions
• It is mainly mechanical and protective in function
• It gives strength, rigidity, flexibility and elasticity to the
plant body

22. PROTECTIVE TISSUE
• The protective tissue include the epidermis and
cork (or phellem)
EPIDERMIS
• The epidermis is present in the outermost part of
the plant body such as leaves, flowers, stem and
roots
• The epidermis is one cell thick and is covered with
cuticle
• Cuticle is a waterproof layer of a waxy substance
called cutin, which is secreted by the epidermal
cells.
• Cells of epidermis are elongated and flattened and
do not contain any intercellular spaces

23. • They are living cells and are similar to parenchyma
cells
Function
• Their main function is to protect the plant from
desiccation and infection
• The cuticle heps to reduce water loss by
evaporation and helps in preventing the entry of
pathogens
CORK
• As plants grow older the outer protective tissue
undergoes certain changes, a strip of secondary
meristem called phellogen or cork cambium
replaces it.
• It has only one type of cells

24. • The epidermis of the leaf is not continuous at some
places due to the presence of small pores called
stomata .
• Each stoma is bounded by a pair of specialised
epidermal cells or two kidney shaped cells called
guard cells
• The guard cells are the only epidermal cells which
contain chloroplast
• The stomata helps in gaseous exchange to occur
during photosynthesis and respiration.
• During transpiration too, water vapour escapes
through stomata

25. COMPLEX PERMANENT TISSUE
• The complex tissue consist of more than one type of
cells having a common origin, they have a common
function
• They transports water, mineral salts(nutrients) and
food materials to various parts of the plant body
• They are of two types
1. Xylem
2. Phloem
• Xylem and the phloem are both the conducting
tissues and known as the vascular tissues ,
together they constitute the vascular bundles.

26. XYLEM
• Xylem is a vascular and mechanical tissue, it is a
conducting tissue
• It is composed of four different types of cells
1. Tracheids
2. Vessels or tracheae
3. Xylem parenchyma
4. Xylem sclerenchyma or fibres
• Except xylem parenchyma all the other xylem
elements are dead and are bounded by thick
lignified walls
• Of the four the vessels are the most important

27. Vessels
• They are shorter and wider than tracheids
• They are tube like structures formed by a row of
cells placed end to end
• the transverse walls between the vessels elements
are partially or completely dissolved to form
continuous channels or water pipes.
Tracheids
• They are elongated cells with tapering ends.
• They also conduct water
• Since they do not have open ends, water passes
from cell to cell via pits

28. • Xylem parenchyma stores food and helps in lateral
conduction of water
Function
• Conduction of water and mineral salts up from the
roots to all parts of the body
• Since the cell walls are lignified they give mechanical
strength to the plant
PHLOEM
• Phloem is composed of the following four elements
1. Sieve tubes
2. Companion cells
3. Phloem parenchyma
4. Phloem fibres

29. Functions
• The phloem helps in the conduction of
photosynthetically prepared food from the leaves to
the storage organs and later from there to the
different parts of the storage organs

30. ANIMAL TISSUES

31. Animal tissues
Epithelial
squamous cuboidal
Coloumnar
or grandular Ciliated
Muscular
Striated Smooth Cardiac
Connective
Areolar
Tendon Ligament
Adipose Skeletal
Cartilage Bone
Fluid
Blood Lymph
Nervou
s

32. • On the basis of the function they perform we can
think of different types of animal tissues
• Animal tissues can be mainly divided into 4
1. Epithelial tissue
2. Connective tissue
3. Muscular tissue
4. Nervous tissue

33. EPITHELIAL TISSUE
• The protective tissue in the animal body is the
epithelial tissue
• The cells of the tissue are tightly packed without
intercellular spaces forming a continuous sheet
• It covers most of the organs and cavities within the
body
• It forms a barrier to keep different body systems
separate
• The epithelium is usually separated from the
underlying tissue by an non-cellular fibrous
basement membrane, which is made of a protein
called collagen
• Skin and lining of the mouth, blood vessels, alveoli
and kidney tubules are made of epithelial tissue

34. Functions
• The cells of the body surface form the outer layer
of skin
• The lining of the mouth, and alimentary canal and
some of the internal organs are protected
• They help in absorption of water and nutrients
• They also help in the elimination of waste
products
• Some epithelial tissues are secretory in function,
they secrete substances like sweat, saliva(mucus),
enzymes etc.

35. The different types of epithelial tissue are
i. Squamous epithelium
ii. Cuboidal epithelium
iii. Columnar epithelium
iv. Glandular epithelium
v. Ciliated epithelium
SQUAMOUS EPITHELIUM
• They are irregularly shaped thin, flat cells which fit together
like floor tiles and form a compact tissue
• It forms the delicate lining of the cavities like mouth,
oesophagus, nose, alveoli etc and of blood vessels and
covering of the tongue and skin
Functions
• It protects the underlying parts of body from mechanical
injury, entry of germs, and drying.
• It forms a selectively permeable surface through which
filteration occurs

37. STRATIFIED EPITHELIUM
• This is found in the skin and covers the external
surface of the skin
• It is a type of squamous epithelium, the cells of
the tissue are arranged in many layers, to prevent
wear and tear
• Since they are arranged in many layers they are
called stratified squamous epithelium

39. CUBOIDAL EPITHELIUM
• It consist of cube like cells which are square in
section
• It is found in the kidney tubules, thyroid vesicles
and glands ( salivary glands, sweat glands, etc)
• It provides mechanical support

41. COLUMNAR EPITHELIUM
• It consist of cells which are taller
• The nuclei are towards the base
• It forms the inner lining of the stomach, small
intestine, gall bladder and colon forming the
mucous membrane
• It facilitates functions such as absorption and
secretion

44. CILIATED EPITHELIUM
• Certain cuboidal or columnar epithelium cells
have a free border which bear thread like or hair
like cytoplasmic outgrowths called cilia
• These cilia can move and their movement pushes
the mucus forward.
• Such cells form the ciliated epithelium
• It forms the lining for the trachea(wind
pipe/respiratory tract), bronchi(lungs), kidney
tubules etc.

47. GLANDULAR EPITHELIUM
• The columnar epithelium is often modified to
form glands which secrete chemicals
• Sometimes the tissue gets folded inwards and
hence the glands are formed

48. MUSCULAR TISSUE
• The muscular tissue are made of muscle cells and these
cells are elongated and large sized , so they are also
called the muscle fibres
• The movement of the body or limbs are brought about
by the contraction and relaxation of the contractile
protein present in the muscle cells.
• Most of the muscular tissue is attached to the bones
and hence are called the skeletal muscles
• The movement of the muscles can be controlled as well
as uncontrolled
• The type of muscles in which the movement is under
our control are called the voluntary muscles
• And the type of muscles where the movement cannot
be controlled are called the involuntary muscles

49. • The muscular tissue can be divided into 3
1. Striated muscles
2. Smooth muscles
3. Cardiac muscles
STRIATED MUSCLES
• The muscles are also known as skeletal muscles or
voluntary muscles
• The type of muscles show light and dark bands or
striations when stained, hence they are also known as
striated muscles
• The cells of this tissue are long, cylindrical, unbranched
and multinucleate.
• They are attached to the bones and help in body
movements
• Each muscle cell is enclosed in a distinct plasma
membrane called the sarcolemma

51. SMOOTH MUSCLES
• These are also known as the unstriated or the
involuntary muscles
• They occur as bundles which are spindle shaped
and have a single nucleus
• The movement of these muscles cannot be
controlled
• The tissue are often seen in the walls of the
alimentary canal, visceral organs except the heart

53. CARDIAC MUSCLES
• They show the charecteristics of both the striated
and smooth muscles
• The cells of this muscles are branched cylindrical
and uninucleate, the intercellular spaces are filled
with the connective tissue
• They have dark and light bands on them
• The muscles around the heart show rhythmic
contraction and relaxation throughout the life ,
and hence these involuntary muscles are also
known as the cardiac muscles

55. CONNECTIVE TISSUE
• The connective tissue is specialized to connect
and anchor various body organs
• It connects the bones to each other, bind the
tissues and give support to various parts of the
body by creating a packing around the organs,
• Thus the main function of the tissue are
binding, supporting and packing
• The cells of the tissue are living and are separated
from each other
• A homogenous gel like intercellular substance
called the medium or matrix forms the bulk of the
connective tissue

56. • The space between the cells are filled with a non
living matrix which may be solid as in bone and
cartilage and fluid as in blood
• Thus blood is a type of connective tissue
• Blood has a fluid matrix called the plasma, in
which the RBC, WBC and platelets are suspended
• The plasma contains proteins, salts and hormones
• The bone is another example of a connective
tissue
• It is a strong and nonflexible tissue, embedded in
a hard matrix composed of calcium and
phosphorus compounds

57. • Two bones are connected to each other by
another type of connective tissue called ligament
• Tissue is very elastic and has strength and
contains very little matrix
• The muscles are connected to the bones by
another type of connective tissue called tendons
• Tendons are fibrous with great strength and
limited flexibility
• Cartilage is another type of connective tissue,
which has widely spaced cells
• The cartilage is seen at the surface of the joints,
nose, ear, trachea and larynx

58. AREOLAR OR THE LOOSE CONNECTIVE TISSUE
• The tissue is found between the skin and the muscles, around
the blood vessels and the nerves and in the bone marrow.
• It fills the space inside the organs
• It supports the internal organs and helps in repair of tissues
after an injury
• Its matrix consist of two kinds of fibres
The white collagen fibres
The yellow elastic fibres or elastin
• Also scattered in the matrix are several kinds of irregular cells
like the
Fibroblast
Adipose cells
Macrophages
Mast cells
immunocytes

60. Functions
• It act as a supporting and packing tissue between organs
• It fixes the skin to the underlying muscles
ADIPOSE TISSUE
• Its an aggregation of fat cells or adipocytes
• Each fat cell is rounded and contains a large droplet of fat
that almost fills it
DENSE REGULAR CONNECTIVE TISSUE
Tendons
Ligaments
SKELETAL TISSUE
Cartilage
Bone

62. BONE
• The bone cells are present in the fluid filled
spaces called lacunae
• All lacunae of the bone communicate with each
other by a network of fine canals called canaliculi
CARTILAGE
• The matrix of the cartilage is composed of
proteins and is known as the hyaline matrix
• The matrix is maintained by the chondrocytes

63. BLOOD
 RBC
 WBC
 Platelets
RBC
• Its large in number and have iron containing red respiratory pigment, the
haemoglobin
• The RBC is also known as the erythrocytes
• they transport oxygen
WBC
• Heamoglobin is absent in them
• The function of these cells is defence and immunity
• They are of five types
 Neutrophils
 Basophils
 Eosinophils
 Lymphocytes
 Monocyte

66. NERVOUS TISSUE
• It is a tissue which is specialized to transmit messages
within the body
• Brain, spinal cord and nerves are all composed of
nervous tissue
• The cells of this tissue are called nerve cells or
neurons
• The neurons have the ability to receive stimuli within
or outside the body and to conduct impulses (signals)
to different parts of the body
• The impulse travels from one neuron to another
• Many nerve fibres bound together make up a nerve
• The neurons have the three main parts

67. The cyton or the cell body
The dendrons and the dendrites
The axon