INTRODUCTION
The living organismseither unicellular like amoeba or multicellular like human beings have different
life processes. In unicellular organism all the life processes are carried out within a single cell.
In multicellular organisms due to increase in body size, it is difficult for each cell to efficiently cope
with the vast variety of the physiological needs of the organisms, so cells differentiate into specific
tissues to perform specific functions. In human being nerve cells carry messages and blood flows
to transport oxygen, food, hormones and waste materials.
In plants vascular tissues conduct food, water and minerals from one part of the plant to other
part. So multicellular organism shows division of labour.
3.
TISSUE - DEFINITION
Agroup of cells that are similar in structure and perform common
function is called tissue.
The term tissue was coined by Bichat.The study of internal structure
of any part of an organism is called anatomy.The study of tissue with
the help of microscope is called histology.
Importance of tissues
Workload of individual cell has decreased.Tissues become organized to
form organs and organs into organ systems. Formation of tissues has
brought about division of labour in multicellular organisms.Multicellular
organisms have higher survival due to improved body organization and
higher efficiency of functions.
PLANT TISSUE
Plants arestationary so they require more of supportive tissue for
obtaining structural strength.
Most of these tissues are dead and hence they provide more
mechanical strength and they require less energy for their
maintenance.
The growth of plants is limited to certain regions.In these regions,
growing tissues are present, which have capacity to divide throughout
life.
Plant tissues can be classified into two groups on the basis of their
division capacity, meristematic tissue and permanent tissue.
MERISTEMATIC TISSUE
These areliving tissues which are capable of
division.These tissues are found in growing regions of
plants. Cells have thin cell wall. Cells contain dense
cytoplasm and do not have vacuoles.Cells contain
prominent and large nucleus. Intercellular spaces are
absent.Metabolically active cells and stored food is
absent.
Function- Meristematic tissue is responsible for the
growth in length and width(girth) of plant.
8.
CLASSIFICATION OF MERISTEMATICTISSUE
(i)Apical meristem
It is present at the growing tips of shoot and root.Root apical meristem is covered by root cap which
protects it from the rubbing of soil particles. They are responsible for increase in the length of shoot
and root.
(ii) Intercalary meristem
Intercalary meristem may be present at the internode as in grasses, bamboo and mints or the base of
Pinus leaves.They are responsible for the growth in length of plant organs.Apical and intercalary
meristem are responsible for primary growth of plant (growth in length).
(iii) Lateral meristem
It lies on the lateral sides of stem and root or occurs along the sides of longitudinal axis of the plant. It
helps in increasing the diameter (girth or width) of plant. Hence helps in secondary growth. Lateral
meristem is of two types, vascular cambium and cork cambium.Vascular cambium produces secondary
phloem and secondary xylem. Cork cambium (phellogen) produces a protective cork on the outside.
9.
PERMANENT TISSUE
They areformed by division and differentiation of
meristematic tissue.
They are composed of those cells which have lost the power
of division (temporarily or permanently) and attained a
permanent shape, size and function. Cells may be living or
dead.
Permanent tissues are of two types, simple permanent tissue
and complex permanent tissue.
SIMPLE PERMANENT
TISSUE
These tissuesare made up of similar types of cells,
that perform a common function.
They are protective and supportive in nature.
Simple tissues are of three types
(i) Parenchyma
(ii) Collenchyma
(iii) Sclerenchyma
12.
PARENCHYMA
It is aliving and basic packaging tissue which consists of
relatively unspecialised cells.
Parenchyma is the first evolved permanent tissue which is
present in all soft parts of plant (therefore called universal
tissue).
Cells of this tissue have thin cell wall which is made up of
cellulose.
Cells of this tissue have cytoplasm with small nucleus and large
vacuole.
Cells are usually loosely packed so intercellular spaces are
present.
FUNCTION
This tissue provides support to the plant and help in storage of
food.
13.
MODIFICATIONS OF PARENCHYMA
(a)Chlorenchyma
Chlorenchyma is the type of
parenchyma in which chloroplasts
(contains chlorophylls) are found.They
are present in mesophyll of leaves.
FUNCTION
Synthesis of food (Photosynthesis).
(b) Aerenchyma
Parenchyma made up of rounded cells
which surrounds the large air cavities.
It is found in aquatic plants or
hydrophytes.
FUNCTION
It provides buoyancy to the aquatic
plants to help them float.
14.
COLLENCHYMA
Cells of thistissue are living, flexible, elongated or vary in
structure. Cells of this tissue are irregularly thickened at
the corners due to the deposition of pectin.Intercellular
spaces are very little or absent It is present below the
epidermis of leaf stalk, herbaceous dicot stem and at the
margin of leaves.
FUNCTIONS
It provides mechanical support (tensile strength) and
elasticity. It allows easy bending in various parts of plant
(leaf and stem) without breaking i.e. it provides flexibility to
plant.
15.
SCLERENCHYMA
Sclerenchyma cells aredead, narrow and long cells which
are devoid of protoplasm.The walls of cells of sclerenchyma
are greatly thickened with deposition of lignin. Such cell
walls are called lignified.The cells of sclerenchyma are
closely packed without intercellular spaces.They are found
in stems, roots, veins of leaves (in vascular bundle), hard
coverings of seed and fruits.
FUNCTIONS
They form hypodermis of monocot stem. It is the main
mechanical tissue which provides mechanical support. It
makes the plant hard and stiff.
16.
CLASSIFICATION OF SCLERENCHYMA
1.Sclerenchyma fibres:They constitute
the major mechanical tissue of the plants
and are abundantly found in plants.
Commercial fibres obtained from plants
(e.g. jute, flax, hemp, husk of coconut)
usually are sclerenchymatous fibres.
2. Sclereids (grit or stone cells):They are
highly thickened and irregularly shaped dead
cells.They are found in various parts of the
plant such as cortex, pith and hard seed coat.
Sclereids provide strength to seed covering
and grittiness to the pulp of many fruits, such
as guava, apple and pear.
COMPLEX PERMANENT
TISSUE
The complextissues consist of more than one
type of cells.
All these cells coordinate to perform a
common function. Complex tissues are of the
following two types :
(i) Xylem or wood (ii) Phloem or bast
20.
XYLEM
Xylem is madeup of four types of cells
1.Tracheids 2.Vessels 3. Xylem fibres - Dead elements
4. Xylem parenchyma - Living element
Tracheids- Tracheids are elongated cells with tapering ends. Since
tracheids do not have open ends like the vessels, so the water has to
pass from cell to cell via the pits.
Vessels or tracheae-Very long tube like structures formed by a row
of cells placed end to end.The transverse walls between the vessels
are completely dissolved to form continuous channels or water-pipes.
Tracheids and vessels help in long distance conduction ofnwater and
minerals vertically or upward from the root system to various parts
of plant.Tracheids and vessels provide mechanical support.
Xylem fibre-These are dead and lignified
sclerenchymatous cells which are mainly
supportive in function.
Xylem parenchyma It is formed of living
parenchymatous cells which helps in storage
of food and lateral conduction of water and
minerals.
21.
PHLOEM
Sieve tubes-Sieve tubesare slender, tube like
structures composed of elongated cells, placed end
to end.Their end walls are perforated by numerous
pores and are called sieve plates.The nucleus of
each sieve tube degenerates at maturity, however
cytoplasm persists in the mature sieve tube.Thus,
nuclei are absent in mature sieve tube elements.
Companion cells -These are associated with sieve
tubes.These are smaller cells having dense
cytoplasm and prominent nucleus.The companion
cells help the sieve tubes in the conduction of food
material.
Phloem parenchyma These are living and thin
walled cells which helps in sideways conduction of
food.They store various materials like resin, latex
and mucilage.They are absent in monocots.
Phloem fibres- are dead sclerenchymatous cells.
Phloem or bast fibres of some plants are source of
commercial fibres e.g. Jute, Hemp, Flax.
Function of phloem- Phloem transport
photosynthetically prepared food materials in both
the directions from the leaves to the storage organs
and latter from storage organs to the growing
regions of the plant body.
EPIDERMIS
It is theoutermost layer of all organs of plant body which is formed from parenchymal
cells. In epidermal cell outside walls are thicker than inner wall. It is mostly single layered
but in desert plant it is multi layered for protection against water loss. It protects the
internal tissue from mechanical injuries and entry of germs.
Cuticle :The outer wall of epidermis of aerial parts of plant secretes and deposits a waxy
substance, called cutin which form a water proof layer called cuticle.
24.
EPIDERMIS
It checks theloss of water by transpiration and mechanical
injuries and invasion of parasitic fungi. Epidermis of leaves has
large number of microscopic aperture called stomata.
Stomata: Each stomata is an elliptical aperture bounded by
two kidney shaped guard cells which regulate opening and
closing of stomata.Transpiration (loss of water in the form
of water vapours) takes place through stomata. Stomata helps
in exchange of gases.
Root hairs: Epidermis of roots (epiblema) have root hairs
which greatly increase their surface area for absorption of
water and minerals.
Root Hair
25.
CORK OR PHELLEM
Corkis the peripheral tissue of old stems and roots of woody
trees and is formed due to activity of cork cambium or
phellogen (secondary / lateral meristem).It is made up of dead
cells with thick wall but no intercellular spaces.The walls of
cork cells are heavily thickened by the deposition of an organic
substance (a fatty substance), called suberin. Suberin makes
these cell impermeable to water and gases and it also helps in
conservation of water in the trees.sides, thus, forming cork
(phellem) on the outer side and the secondary cortex or
phelloderm on the inner side.
Commercial importance of cork- Cork is light and highly
compressible and cork is used in the making of a variety of
sports goods such as cricket balls, table tennis, shuttlecocks,
wooden paddles etc.
EPITHELIUM - NATURE
Itis the simplest tissue. It is the protective tissue of animal's body. It covers most
organs and cavities within the body. It also forms a barrier to keep different body
systems separate.Epithelial cells are closely packed and have small amount of
cementing material, so there is very little inter-cellular spaces present between
the cells. Due to absence or less intercellular spaces, blood vessels, lymph vessels
and capillaries are unable to pierce this tissue, so blood circulation is absent in
epithelium. Hence cells depend for their nutrients on the underlying connective
tissue. It always rest upon underlying connective tissue.At the junction of the
Epithelial tissue and connective tissue a layer is present which is called basement
membrane (non cellular fibrous), formed of mucopolysaccharides and collagen
fibrils.
29.
TYPES OF EPITHELIUM
(i)Squamous
Description: Flattened cells, extremely thin.
Common locations: Blood vessel walls, alveoli of
lungs, Buccal cavity, skin,
Function: Diffusion
30.
TYPES OF EPITHELIUM
(ii)Cuboidal
Description: cube like cells, may have microvilli at its
free surface
Common locations: lining of kidney tubules, thyroid
gland, ducts of salivary glands and sweat gland. It forms
germinal epithelium of gonads (testes and ovaries)
Function: Secretion, absorption, mechanical support and
germ cells formation.
31.
TYPES OF EPITHELIUM
(iii)Columnar (Pillar like)
Description: tall slender cells ; may have microvilli at
their free surface.
Common locations: Inner lining of small intestine,
stomach, colon and part of respiratory tract lining.
Border of microvilli present at free surface end of
each cell increases absorption efficiency in small
intestine.
Function: Secretion, absorption.
32.
TYPES OF EPITHELIUM
Ciliatedepithelium
Description: It consists of cells that bear hair like
structures (cilia) on its external surfaces. Cells in it
may be cuboidal or columnar in shape. Cilia helps in the
movement of substances.
Common location: It is found in kidney tubules,
trachea, oviduct, etc.
Functions: It helps in movement of substances.
33.
TYPES OF EPITHELIUM
Glandularepithelium
Description:Tall, slender cells, some cells from
the free surface invaginate inside to form
secretory cells – goblet cells.
Common location: Lining of intestine & glands
Function: Secretion of mucus and other
secretions.
CONNECTIVE TISSUE
The cellsof connective tissue are loosely spaced and
embedded into a non cellular matrix.The matrix may
be solid (as in bone), soft (as in loose connective
tissue), or liquid (as in blood).
On the basis of nature of matrix, connective tissue
are:-
(1) Connective tissue proper
(2) Fluid / vascular connective tissue
(3) Skeletal connective tissue
36.
CONNECTIVE TISSUE PROPER
(i)Loose connective tissue or Areolar connective
tissue
Loose connective tissue is a mass of widely scattered cells
whose matrix is a loose weave of fibres. Many of the fibres
are strong protein fibres called collagen. Loose connective
tissue is found beneath the skin and between organs. It is a
binding and packing material whose main purpose is to
provide support to hold other tissue and organs in place.It
is found between the skin and muscles, around blood
vessels, nerves and in bone marrow.
37.
FUNCTIONS OF AREOLARCONNECTIVE TISSUE
(i) It helps to hold various tissues together in any organ.
(ii) It helps in the repair of body tissues after any injury.
(iii) Histocytes (amoeboid cells) of this tissue engulf foreign particles and
protect against diseases.These are also known as macrophages.
(iv) Mast cells in the tissue are concerned with allergic and inflammatory
reactions.
(v) It binds skin with the underlying tissues.
38.
ADIPOSE TISSUE
It consistsof adipose cells (Adipocytes) filled with
fat globules in loose connective tissue. Each adipose
cell stores a large droplet of fat which is used to
provide energy.Adipose tissue pads and insulates
the animal body.
Location: It is found in the subcutaneous layer
below the skin, around the heart,brain and below
the eye balls, blubber of whales & elephants, hump
of camel, etc. It is a prominent component of skin of
mammals living in polar regions.
39.
FUNCTIONS OF ADIPOSETISSUE
(i) It acts as insulator and prevents loss of heat from the body.
(ii) It helps in the storage of food in the form of fats.
(iii) It provides body contours (shapes).
(iv) It forms cushion like shock-absorbing structures below the vital
organs such as heart, kidney, eye balls etc.
40.
FIBROUS CONNECTIVE TISSUES
(a)White fibrous connective tissue
The matrix of this tissue contains abundant
white fibres forming layers or bundles
making it inelastic.The white fibres are
made up of collagen protein.Sheets of this
tissue are found in the coverings of the
bones, cartilages, kidneys etc.Bundles of this
tissue called tendons, attach muscles to the
bones.
41.
FIBROUS CONNECTIVE TISSUES
(b)Yellowfibrous connective tissue
This tissue is very elastic due to the presence of
a network of very elastic yellow fibres in its
matrix.The yellow fibres are made up of elastin
protein. Sheets of this tissue are found in
covering of the blood vessels. Bundles of this
tissue are called ligaments that attach the bones
to each other at the joints.
43.
FLUID / VASCULARCONNECTIVE TISSUES
It is a special type of connective tissue which maintains link among different
parts of the body.
It receives materials from certain parts of the body and transports them to
the other parts.
It constitutes the transport system of animals.
It consists of two basic components – blood and lymph.
44.
BLOOD
Blood is composedof blood cells present in liquid matrix called plasma.Blood is
approximately 55 percent of plasma and 45 percent blood corpuscles.Plasma
contains water, salts, sugars, lipids and amino acids.
Blood corpuscles are of 3 types:
(A) Red blood cells or Erythrocytes.
(B) White blood cells or leucocytes
(C) Platelets or thrombocytes (These are spindle-shaped non-nucleated cells
numbering 200, 000 to 300,000 per mm3 of blood.They help in the clotting of
blood).
45.
BLOOD
(A) RBC’s orErythrocytes
These are the most abundant corpuscles out of all the types and are
about 5 million in one mm3 of blood.They are biconcave, nonnucleated,
disc-like in mammals, whereas oval, biconvex and nucleated in fishes,
amphibians, reptiles and birds.They contain red-coloured respiratory
pigment called haemoglobin that helps in the transportation of respiratory
gases.
46.
BLOOD
(B) WBC’s orLeucocytes
These are irregular, amoeboid, phagocytic cells with one to many
lobed nucleus.These cells protect the body against diseases by
engulfing bacteria and other foreign particles (phagocytosis) and are
hence called ‘soldiers of the body’.They also provide resistance
against diseases by producing proteinaceous substances called
antibodies.Their number is about 6000-8000 per mm3 of blood.They
are of five types : monocytes, lymphocytes, acidophils, basophils and
neutrophils.
47.
TYPES OF LEUCOCYTES
Granulocytes
Intheir cytoplasm granules are present which can be stained by
specific dye.Nucleus is multilobed and lobes are interconnected by
protoplasmic strand.Produced in Bone marrow –
They are (i) Acidophils, (ii) Basophils (iii) Neutrophils
48.
GRANULOCYTES
(i) Acidophils/Eosinophils
Amoeboid inshape.
In their cytoplasm acidophilic granules are
present which can be stained by acidic dye
Eosin.
Nucleus is bilobed.
They protect body against allergy & parasitic
infection.
49.
GRANULOCYTES
(ii) Basophils
Amoeboid inshape.
Smallest granulocytes.
In their cytoplasm basophilic granules are present
which can be stained with basic dye methylene blue.
Nucleus is 3 lobed. 'S' shaped.
Their main function is to secrete heparin, histamine &
serotonin.
50.
GRANULOCYTES
(iii) Neutrophils
Maximum innumber.Amoeboidal in shape. In their
cytoplasm granules can be stained by any dye (acidic,
neutral, basic). Nucleus is multilobed.They can squeeze
& comes out from the wall of blood capillaries in tissue.
This phenomenon is called Diapedesis. Phagocytic in
nature. Destroy bacteria & viruses by phagocytosis. Due
to their smaller size & phagocytic nature they are called
Micropolice man.
51.
TYPES OF LEUCOCYTES
(2)Agranulocytes
Cytoplasm is clear & granular.
Produced in bone marrow.
They are of 2 types (i) Monocytes (ii) Lymphocytes
52.
AGRANULOCYTES
(i) Monocytes
Largest BloodCorpuscles. Nucleus kidney
shaped/bean shaped.Power of diapedesis is present.
Active motile WBC. Phagocytic in nature. Destroy
bacteria & viruses by phagocytosis so called
Macropoliceman.Also called scavanger of blood
because they engulf damaged or dead & minute bits
of blood corpuscles.
53.
AGRANULOCYTES
(ii) Lymphocytes
Amoeboid shape.Life span in blood - 5 - 7 days or less than 10
days but in connective tissue it may be month/year/whole life.
Lymphocytes are of two types.
A. T – LYMPHOCYTES
Produced in bone marrow but mature in thymus gland.
B. B – LYMPHOCYTES
Produced in bone marrow and mature in bone marrow. Its
function is to produce, synthesize & transport antibodies.
FUNCTIONS OF BLOOD
(i)It transports nutrients, hormones and vitamins to the tissues and carries
excretory products from the tissues to the excretory organs.
(ii) The RBC's of blood helps in the transport of respiratory gases,(oxygen & CO2).
(iii) The WBCs fight with diseases by producing antibodies and engulfing the germs
(antigens).
(iv) Blood platelets help in the clotting of blood.
(v) Blood helps in thermoregulation, water balance and maintenance of pH of body.
56.
LYMPH
Lymph is actuallyfiltered blood which is
similar to blood in composition except
that it is devoid of RBC, platelets and
some blood protein.WBC are present in
abundance in lymph. Due to the absence
of RBC(haemoglobin), lymph is colourless.
57.
FUNCTIONS OF LYMPH
(i)It acts as a "middle man" for exchange of various material between blood and
tissue.
(ii) Helps in the transportation of fat absorbed from intestine to the venous
blood.
(iii) Keeps the tissues and organs of the body moist.
(iv) Lymphatic organs (lymph nodes, spleen) produce lymphocytes which in turn
produce antibodies to strengthen the immune system of the body.
58.
SKELETAL CONNECTIVE TISSUES
Bone-It is a rigid connective tissue that has a matrix of
collagen fibres embedded in calcium and phosphorous
compounds, giving it greater rigidity and strength. It is
the hardest connective tissue that forms the skeleton of
vertebrates. Bone is surrounded by a thick sheath called
periosteum. Like other connective tissues it is also made
of matrix and cells.The matrix of bone is very hard
because of the presence of salts such as calcium
phosphate( maximum invertebrate bone), CaCO3, etc.
and a protein ossein.
59.
BONE
The long bonesare usually hollow containing a cavity called marrow
cavity. It is full of bone marrow. In the solid matrix are present
longitudinal canals called haversian canals, which are interconnected
by transverse Volkmann’s canal.The matrix is present in the form of
layers called lamellae.These lamellae are present in the form of
concentric rings around the marrow cavity and around the canals.
In these lamellae are present spaces called lacunae.The lacunae
have fine channels called canaliculi.The lacunae contain bone
forming cells osteocytes.Another type of bone-forming cells called
osteoblasts are present in the form of two layers, one outer and the
other inner to matrix. Growth of bone is bidirectional.
60.
FUNCTIONS OF BONE
(i)It provides support for muscle attachment.
(ii) It protects the internal organs from mechanical injury.
(iii) It serves as a reservoir for calcium.
➢ Immature bone cells (Osteoblast), mature bone cells (Osteocytes),
Immature cartilage cells (Chondroblast), mature cartilage cells
(Chondrocytes). Bone destroying cells (Osteoclast), cartilage destroying cells
(chondroclast)
61.
CARTILAGE
It is aconnective tissue with an abundant
number of collagen fibres in a rubbery matrix.
The matrix is made up of proteins and sugars. It
is both strong and flexible but softer than bone.
It forms the embryonic skeleton of vertebrates
and the adult skeleton of sharks and rays. It also
occurs in the human body in the ear pinna, tip of
the nose, trachea, larynx and surrounding ends of
joints such as knees.
MUSCULAR TISSUE
Muscular tissueis distinguished from
other tissues by its unique ability to
contract & relax and thereby perform
mechanical work. It is responsible for
movement of body organs and
locomotion of body.
64.
GENERAL STRUCTURE OFMUSCULAR TISSUE
The structural unit of muscle tissue is the muscle
cells which because of its elongated shape is also
called muscle fibre.
The contractility is due to the presence of
contractile proteins (Actin & Myosin) in the
muscle fibre.
The plasma membrane of muscle cells is called
sarcolemma and endoplasmic reticulum of muscle
cell is called sarcoplasmic reticulum.
65.
GENERAL FUNCTIONS OFMUSCULAR TISSUE
(i) It supports the bones and other organs of the body.
(ii) Muscles help in peristalsis of gut, heart beat, etc.
(iii) Muscles cause movements of body parts and locomotion of the animals.
(iv) Facial expression also depends on muscles.
(v) Contraction of muscles causes birth of a baby.
NERVOUS TISSUE
The nervoustissue, contains densely packed
cells called nerve cells or neurons, is present
in the brain, spinal cord and nerves.The
neurons are specialised for conduction of
nerve impulses.They receive stimuli from
within or outside the body and conduct
impulses (signals) which travel from one
neuron to another neuron.
69.
STRUCTURE OF NEURON
Eachneuron has following 2 parts :
(i) Cyton or cell body:
Contains a central nucleus and cytoplasm with characteristic deeply stained particles
called Nissl's granules (i.e. clumps of ribosomes and rough endoplasmic reticulum).
(ii) Cell Processes
(a) Dendrites
(b) Axon
70.
STRUCTURE OF NEURON
(ii)Cell Processes
(a) Dendrites:These may be one to many, generally short and branched cytoplasmic
processes. Dendrites are afferent processes because they receive impulse from receptor
or other neuron and bring it to cyton.
(b) Axon: It is single generally long efferent process which conducts impulse away from
cyton to other neuron. Longest cell in body is neuron because axon can be more than
one metre long.Axon has uniform thickness, but it has terminal thin branches called
telodendria.Terminal end buttons or synaptic knobs occur at the end of telodendria.
