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UNIQUE EDUCATION PORTAL
TISSUE CLASS9
1/22/2020
VIKASH KUMAR
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TISSUE
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Living organisms in
this world comprise of cells.
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There are unicellular
as well as multicellular organisms present in this world.
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In unicellular
organisms, the only single cell is capable of performing several functions such
as Respiration, Digestion and Clearing of the cell.
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In multicellular
organisms, there is a division of labor. There are different types as well as
groups of cells that perform different functions in a multicellular
organism. For Example,
In animals muscle cells are responsible for causing movement, nerve cells are
responsible for carrying messages and signals from one part of the body to
another and blood is responsible for transportation of food and oxygen to
different parts of the body.
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In plants, there are
vascular tissues that are responsible for carrying food and water two different
parts of a plant.
The
Formation of Tissues
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Cells form groups
cells that need to perform a single task often group together.
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This grouping of cells
together to perform a function efficiently is called a Tissue.
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For Example,
Muscles and Blood.
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The tissue cells have
the same structure and they perform the same function.
Tissues
of Plants and Animals
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Plant Tissues
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Animal Tissues
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Plants do not move so their tissues are predominantly the ones
that provide support to them so that they can stand erect.
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Animals need more energy as compared to plants because they
are not stationary. Their tissues are the ones that can support movement.
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These tissues are made up of dead cells because dead cells can
also provide mechanical strength to the plants and do not require much
maintenance.
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The tissues in case of animals are made up of living cells so
that they can move and perform several functions.
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Only certain parts of the plant can grow. The tissues present
in such regions of and divide themselves and form new tissues.
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Cells in animals grow uniform early and not only in certain
regions of the body.
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The structure of plant tissues is not very specialized as
compared to animals
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The organs and organ systems in animals are highly developed.
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Plant
loading...
Tissues
Figure
1 Types of Plant Tissues
Meristematic
Tissue
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Only certain parts of
a plant tend to grow. The tissues located in such parts are called meristematic
tissues.
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They have the
capability to divide themselves and form new tissues. They have thin cell wall
made of cellulose. Also have dense nucleus and cytoplasm but lack vacuoles.
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They can further we
classify differently based on the areas of the plants where they are located -
o Apical
o Lateral
o Intercalary
Figure
2 Location of meristematic tissue
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Apical Meristem
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Lateral Meristem
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Intercalary Meristem
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They are responsible
for the growth of stems and roots in the plants
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They are found on
the tips of the roots and stems.
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They are responsible
for increasing the circumference of the middle part of the stem and hence are
found there.
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These tissues are
present at internodes or stem regions between the places at which leaves
attach.
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Why there are no vacuoles in the intercalary meristem?
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Vacuoles are
responsible for storage of food in water. The intercalary tissues do not store
them. They are rather responsible for manufacturing them.
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Moreover, vacuoles
contain sap which provides rigidity to a cell. This property of vacuoles may
not allow the intercalary tissues to divide and manufacture new cells. Hence
vacuoles are not present in them.
Permanent
Tissue
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The cells that are
formed by the meristematic tissues often have to take a certain role in the
plant and thus, they lose their ability to divide and form more cells. They
then become the permanent tissues of the plants.
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Differentiation - The process by which cells of the meristematic tissues convert
themselves into a permanent tissue by taking a fixed shape, size and function
is called differentiation.
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Types of Permanent Tissues:
o Simple Permanent Tissues
o Complex Permanent Tissues
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Simple Permanent Tissues are of five types:
o Parenchyma
o Chlorenchyma
o Aerenchyma
o Collenchyma
o Sclerenchyma
Figure
3 Simple Permanent Tissue
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Parenchyma
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Collenchyma
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Sclerenchyma
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These tissues are responsible for photosynthesis, storage of
food, gaseous exchange and floating of plants.
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These tissues are responsible for providing flexibility to the
plants so that they can bend easily.
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These tissues are responsible for making plants hard and
rigid.
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They are a group of living cells with cell wall made of
cellulose.
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They are a group of living cells with cell wall made of
cellulose and pectin.
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They are made up of dead cells having cell wall made of
lignin.
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The parenchyma cells have large intercellular spaces between
them.
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They have a little intercellular space in between them.
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The cells do not have any intercellular spaces.
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There are thin walls that surround each cell.
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The cells present in these tissues are broad and irregularly
thick at corners.
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The cells have a long structure with thick walls.
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They are found in leaves and newly formed branches.
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They are present in leaves and stems of a plant.
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They are found in stems, veins of the leaves and coverings of
nuts and seeds.
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Chlorenchyma
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These tissues are
similar to that of parenchyma but they also contain chlorophyll in them.
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Due to the presence of
chlorophyll, they are capable of performing the process of photosynthesis in
plants.
Aerenchyma
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They are found in
aquatic plants.
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They are also similar
in structure to that of the parenchyma but they have large air cavities in
them.
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These cavities allow
the aquatic plants to float in water.
What is Lignin?
The cell walls of dead
cells have a substance called lignin in them which provides rigidity to the
cells. Lignin acts as the cement for the cells.
Epidermis
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The outermost layer of
the cell is known as the Epidermis.
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It covers the entire
plant.
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It is a thin layer of
single cells but in places with less water, the epidermis of the plants can
become thick in order to avoid frequent water loss.
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The cells are flat and
they have no intercellular spaces between them.
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The outer walls of the
epidermal cells are thick and the inner walls are thin.
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The epidermal cells
often have long hair-like structures in roots which facilitate the absorption
of water.
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The main function of
the epidermis is to protect the plants from fungi, water loss and any injuries
by secrets a wax-like water-resistant substance called as Cuticle on the surface of the plants which protects
the plants.
Figure
4 Epidermis
Stomata
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Stomata are pore-like
structures that are present in the epidermis of the leaves.
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These pores are
enclosed by two cells that have a similar shape as a kidney. These are
called Guard Cells of Stomata. Guard cells are modified epidermal cells.
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Guard cells are
responsible for the exchange of gases and transpiration.
Transpiration
(OLYMPIAD)
Figure
5 Transpiration
The plant cells when
sometimes have extra they lose it in the form of water evaporates through
stomata. This process is called Transpiration.
Role
of Transpiration in Plants – (OLYMPIAD)
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Exchange of Gases - Plants absorbs carbon dioxide and release oxygen through
transpiration.
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Prevent the Plants from Overheating - The leaves absorb sunlight during the
process of photosynthesis. Some of it is used in the photosynthesis process
while the rest is radiated as Heat Energy. We know that absorption of water causes cooling of the
surrounding area. Therefore transpiration keeps the leaves cool.
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Transportation of Food and Water in Plants - The roots of the plants absorb
minerals and water present in the soil through transpiration and they are then
distributed in the plant through transpiration stream.
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Movement of Water in Plants – As plants lose water in the form of water vapors, the
density of water in leaves becomes low. So the water from the higher density
areas such as the roots move up to lower density areas through a force
called Transpirational Pull.
Which gas is necessary for the process of photosynthesis?
The carbon dioxide gas
is necessary in the process of photosynthesis. Plants use carbon dioxide along
with water and sunlight to produce glucose in the process of photosynthesis.
Plants take in carbon dioxide and release oxygen as a byproduct of the
photosynthesis process.
Why do plants in desert areas have a waxy coating of cutin over
them? (OLYMPIAD)
The epidermis cells of
plants that are found in deserts have a waxy coating of cutin over them because
it prevents water loss from the plants surface since water is already scarce in
such areas.
Why do branches of old trees are different than the stems of a new
plant?
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As a plant grows older
the meristematic cells start covering the upper layer of the plants instead of
the epidermis.
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These are the dead
cells that have no special function in the plants but to provide them rigidity.
They make the branches of the plants thick.
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This is often called
the Bark or
the thick cork of the tree.
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The bark of the trees
contains a substance called Suberin which makes it waterproof and does not allow gaseous
exchanges. (OLYMPIAD)
Complex
Permanent Tissues
Complex Permanent
Tissues comprise of different kinds of cells. These different types of cells
coordinate with each other and perform a common function in these tissues. Two
Complex Permanent Tissues are - Xylem and Phloem.
Figure
6 Xylem and Phloem
Similarities
between Xylem and Phloem
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Their main function is
to carry food and water in the plant.
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Both have a vascular
bundle which is a conductive tissue in plants that helps them survive in
different environmental conditions.
Xylem
Xylem is made up of
dead cells having a thick cell lining. It consists of following elements-
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Tracheids and Vessels – They have broad tubular structure so that we can allow
transportation of food and water in the plants vertically.
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Xylem Parenchyma – It stores food and helps in transportation of water
horizontally in the plants.
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Xylem Fibers –
They support transportation
Phloem
Phloem is made up of
living cells and it allows the movement of food from leaves to other parts of
the plant. It has the following elements –
Sieve Tubes –
Broad shaped cells with porous walls
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Companion Cells – They facilitate the functions of the sieve tubes
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Phloem Fibers –
Provide flexibility to the phloem
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Phloem Parenchyma – Stores starch and proteins
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Xylem
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Phloem
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Made of
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Dead Cells
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Living Cells
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Cell wall thickness
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Thick
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Thin
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Cell wall material
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Lignin (rigid)
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Celluloses
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Permeability
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Impermeable
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Permeable
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Cytoplasm
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None
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Cytoplasm lining
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Transports…
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Water & minerals
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Food
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Carried to….
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Leaves
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Growing parts & storage organs
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Direction of flow
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Upwards
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Up & down
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Tissue alos has …
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Fibres
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Companion cells
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Animal
Tissue
Figure
7 Types of Animal Tissues
1.
Epithelial Tissue
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They are the
protective tissues of the human body. They cover many organs and cavities that are
present inside the body.
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Where are the epithelial tissues found in the human body?
o The lining of the blood vessels
o The lining of the mouth
o Kidney tubules
o Skin
o Lung alveoli
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Structure and functions of the epithelial tissues -
o The main function of the epithelial tissues is
to act as a barrier and separate different organs and systems from each other.
o There is no space between the cells of
epithelial tissues
o The cells are permeable. This makes it
possible for them to exchange materials between different parts of the body and
also between the body and the external environment.
o The epithelial tissues remain separated from
the tissues beneath them because of a thin membrane over them.
Figure
8 Types of Epithelium
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Different types of epithelium tissues
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Simple Squamous
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Stratified Squamous
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Columnar
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Ciliated Columnar
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Cuboidal
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Glandular
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Structure
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They have delicate cell lining and possess a flat thin
structure
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The epithelium Squamous cells are arranged in several layers
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They are the column-like shape tissues
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Columnar epithelial tissues which have Cilia present on them
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They are cube-shaped cells which are involved in absorption
and secretion.
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These are special gland cells that can secrete substances
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Found in
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Alveoli and bowman’s capsule- nephron in kidney
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Skin
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Intestine
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Respiratory system
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Kidney tubules
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Sweat glands in the skin
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2.
Connective Tissues
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Structure and function of connective tissues
o They are loosely bound cells present in an
intercellular Matrix.
o This matrix can be of different types – Dense,
Rigid, Fluid or Jelly-like.
o Depending upon the functionality of the
connective tissue, the nature of the matrix varies in them.
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Examples of Connective Tissues
Figure
9 Connective Tissues
Blood
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The main function of
blood is to transport gases, food, waste materials and hormones in the body.
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Therefore, blood has a
fluid Matrix present in it which is called Plasma.
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The plasma contains
the red blood cells, the white blood cells and blood platelets.
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The RBC have
hemoglobin pigment which carries oxygen to tissues.
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White blood cells
fight diseases and platelets are involved in clotting of blood when injured.
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The plasma also
contains proteins and hormones in it.
Lymph
(OLYMPIAD)
Lymph is a colourless
fluid that carries white blood cells throughout the human body in lymphatic
vessels. There are lymphoid organs present in the body that produce lymph and
together form the lymphatic system. Some of them are lymph nodes and tonsils.
Figure
10 Lymph Capillaries
Lymph is similar to blood except for a few differences:
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It contains only white
blood cells.
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It contains less
amount of blood proteins, calcium and phosphorous but more glucose.
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It flows in one
direction only.
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Lymph moves in the
body through its normal function unlike blood which is pumped by the heart.
Constituents
of Lymph:
Lymph Plasma – Lymph Plasma carries infection-fighting proteins along with
other substances such as water, calcium and phosphorous.
Lymph Corpuscles – Lymph Corpuscles comprises white blood cells. Red blood cells
and platelets are not present in lymph.
Functions
of Lymph:
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It carries oxygen and
minerals to the cells in the body and carries back carbon dioxide and waste
materials back into the blood.
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It keeps the body
cells moist.
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It maintains the
volume of the blood.
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It helps in
eliminating harmful bacteria and virus from the body and hence is responsible
for the immunity of human beings.
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It absorbs fats from
the intestine and transports them throughout the body.
Bones
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Bones form a framework
of the body over which the muscles are wrapped together.
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The bone tissue is
strong and inflexible in nature.
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Therefore, the bone
cells are present in a rigid matrix which is formed from calcium and
phosphorus.
Haversian
Canals (OLYMPIAD)
Figure
11 Haversian Canal
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The bones comprises of
microscopic tubes called Haversian Canals.
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They are contained in
osteons, rough cylindrical structures present along the axis of the bone.
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They allow the blood
vessels, lymphatic vessels, and nerve fibres to travel through them.
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These canals have
concentric channels called Lamellae around them.
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The Haversian canals
communicate with bone cells through connections called Canaliculi.
Cartilage
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Cartilage is present
over the joints of the bones and provides them with a smooth structure.
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For Example in
the nose tip and ear pinna, trachea, larynx.
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They contain solid
matrix made of protein and sugar. They have homogenous matrix.
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It provides support
and flexibility to various parts of our body.
Ligaments
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A ligament connects
two bones together.
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It has an elasticity
which facilitates the connection.
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The cells of ligaments
have a little matrix.
Tendons
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The tendons tissues
are responsible for connecting bones and muscles together.
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They have limited
flexibility but very great strength.
Areolar
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This tissue acts as a
filter in between the spaces present inside the organs of the body.
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It helps in repairing
other tissues as well.
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It is found in the
skin and bone marrow.
Components
of the Areolar Connective Tissue
Figure
12 Components of the areolar connective tissue
1.
Cells (OLYMPIAD)
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Fat Cells (Adipocytes) – They are responsible for secretion of lipids.
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Fibroblasts –
They are the present in the highest amount in areolar tissues. They are
responsible for secretion of fibres.
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Mast Cells –
They release histamine that plays role in allergic reactions
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Macrophages – They eat any germs or infectious cells in the body
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Plasma Cells –
They produce antibodies
2.
Fibres
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Collagen Fibres – They provide tensile strength to the tissue
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Elastin Fibres – They provide elasticity to the tissue
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Ground Substance – It is a fluid matrix that holds cells and fibres of the
tissue
Adipose
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Fats are stored in our
body in the adipose tissues.
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They are found below
the skin and between the organs of the body.
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Provides cushioning to
the organs.
3.
Muscular Tissue
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It is made up of
muscle fibers which are long cells.
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It allows movements in
our body.
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How muscles can cause movement?
They contain special
proteins called Contractile Proteins. These proteins cause contraction and relaxation of the
muscles.
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There are two kinds of
muscles found in our body - Voluntary Muscles and Involuntary Muscles.
Figure
13 Muscular Tissue
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Striated/ Skeletal/ Voluntary muscles
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Smooth/ Unstriated/Involuntary muscles
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We can move them according to our own will
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We cannot start or stop the movement of involuntary muscles.
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They are also
called Skeletal Muscles as they are attached to the bones.
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They also
called Smooth Muscles.
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They are also
called Striated Muscles because of the presence of dark and light bands over
them
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They are also
called Unstriated Muscles because they do not have any light or dark bands on
them.
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The cells of voluntary muscles have more than one nucleus,
they do not have any branches, and have a long cylindrical structure.
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The cells of the involuntary muscles are long and have pointed
ends.
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For
Example, Muscles of our
hands and legs.
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For
Example, The muscles in the
alimentary canal and the Iris of our eyes.
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Cardiac Muscles
o These are special kinds of involuntary
muscles.
o The muscles of the heart are called Cardiac Muscles they perform rhythmic contraction and
relaxation throughout our life.
o They are cylindrical in shape, they have
branches and there is a single nucleus.
o Cardiac muscle consists of individual heart
muscle cells connected by intercalated discs to work as a single functional organ
4.
The Nervous Tissue
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How do we react to stimuli?
o This is because of the nervous tissues present
in our body. They are capable of transmitting information quickly from the
brain to different parts of the body and vice-versa.
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Therefore nervous
tissues are found in nerves, brain, and spinal cord.
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The Nervous tissue is
made up of cells called the Nerve Cells or Neurons.
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These neurons connect
together to form the nerves of our body.
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Structure of a Neuron
o It is an elongated cell with a Cell Body that
consists of some branch-like structure called Dendrites.
o There is a Nucleus present in the center of
the cell body.
o The Nerve Endings of the cell are connected
with the cell body via Axon.
o A nerve cell can be up to 1 m long.
Figure
14 Structure of Neuron
The
Structure of Neuron
1. Dendrites
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They are tree-like
extensions (highly-branched) at the beginning of a neuron.
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They increase the
surface area of the neuron.
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They receive chemical
signals from different neurons of the body.
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They then convert
these chemical signals into electrical signals and pass them to the neuron cell
body.
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A neuron can have a
single dendrite or multiple dendrites
2. Cell Body
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Also called Soma.
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The main function of
the cell body and nucleus of the neuron is to maintain the functionality of the
cell.
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It does not play an
active role in the transmission of the signal.
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It produces proteins
that are required by different parts of the neuron to work properly.
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It contains different
cell organelles such as mitochondria, Golgi apparatus etc that perform various
functions of the cell.
3. Axon
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Neurons have one axon
in general.
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It is a long structure
that connects the cell body to the terminals and it also connects with other
neurons, cells and organs of the body through nerve terminals.
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It allows in fast
transmission of signals. The larger the diameter of the axon the faster it will
transmit signals.
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It is covered with a
special insulating substance called myelin. It helps in rapid transmission of
signals.
4. Schwann Cells (OLYMPIAD)
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The Myelin sheath that
covers the axon is produced by Schwann cells.
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The Myelin sheath
keeps the signal intact
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