Tissues: Cells of the same origin, structure and function, combined into groups are called

tissues

Plant Tissues:
● They are mostly dead and supportive
● They have certain areas of growth called meristematic regions
● They do not require a lot of energy as their cells are mostly dead
● They can be classified into Meristematic Tissues and Permanent Tissues

➔ Meristematic:
● They are continuously dividing
● Their only function is to increase the no. of cells
● They have abundance of cytoplasm
● Cells are usually alive
● They do not have a vacuole
● Cell walls are thin
● They arise from pre-meristematic tissues
1) Apical Meristem: It is found on the tips of roots and shoots. It increases the height of
plants
2) Lateral Meristem: It is found on the sides of the plants. It increases girth of the plants.
It causes secondary growth
3) Intercalary Meristem: It is found on the nodes, internodes and bases of leaves. It
increases the size of fruits and flowers. It also causes new plants to form -- tertiary
growth

➔ Permanent Tissues:
● They have lost the ability to divide
● Their function is that of storage, photosynthesis and mechanical support
● Cytoplasm may or may not be present
● Vacuole is present
● Cells may be dead or alive
● They have thick cell wall
● They arise from mature meristematic tissues
● They can be classified into Simple Permanent and Complex Permanent

★ Simple Permanent:
They are tissues which are made up of only one type of cell
1) Parenchyma:
It is living
Structure: Spherical, with big intercellular spaces
Function: Storage (food, oil chlorophyll)

2) Collenchyma:
It is living
 Structure: Almost round, with medium intercellular spaces and thick corners (wall
thickenings)
Function: Easy bending without breaking (flexibility)

3)Sclerenchyma:
It is dead
Structure: It is regular with lignin deposits and no intercellular spaces
Function: Provides mechanical support and strength

4) Protective tissues:
They are the outermost layer of the plant
They protect the plant from pathogens and bacteria
They can be classified into Epidermis and Cork
1) Epidermis:
It is present on every part of the plant
It is one layer only
It prevents the entry of bacteria, parasitic fungi, water loss and
mechanical injury
It has a stomata to allow transpiration/exchange of gases
In desert plants the stomata is sunken
It is present as long hair in roots
In plants located in rainy areas there is an outer covering which is
waterproof called the cuticle. The cuticle prevents entry of water and
bacteria

2) Cork:
It is present on old stems and roots
It is made of a chemical called suberin which makes the layer of cork
impervious to water and gases
It is formed via the secondary meristem
It is multilayered
Cells are compactly arranged and rectangular
There are small pores at intervals called Lenticels which allow
transpiration/exchange of gases
When old cells die they are replaced by tannins, resins, and air

★ Complex Permanent:
They are made up of many different types of cells
Their main function is to help with the conduction of materials throughout the
plant

1) Xylem:
It transports water through the plant (upward direction)
All cells are dead, only one is alive
 It does not take up energy
It is formed by the following : Vessels and Tracheids - tube like structure which
allow the passage of materials through the plant, Xylem Parenchyma - Stores
food, Xylem Fibres - provide mechanical support

2) Phloem:
It transports food from the leaves to every other part of the plant (Both upwards
and downwards direction)
Most of its cells are alive, only one is dead
It uses energy from Adenosine Triphosphate (ATP)
It comprises : Sieve cell - Transport organic material, Sieve tubes - transport
carbohydrates, Companion cell - shortest path of transportation, Phloem
parenchyma - used for storage, Phloem fibres - provide mechanical support

Animal Tissues:
● Almost all of them are alive
● Every region can grow
● They take up more energy as all of them are alive
● They are of four types

1) Epithelial:
It is the protective layer of the animal tissues
It covers organs and acts as a packing between layers
Has fibrous membrane basement
No gaps
They are of four kinds:
1) Squamos Epithelial:
It has only one layer
It is has thin, flat cells
It forms the lining of hollow organs such as the oesophagus and the mouth

2) Striated Squamos Epithelial:

It has multiple layers
It is present in areas which retain wear and tear to prevent it. For eg. Palm, Sole
of feet

3) Cuboidal Epithelial:
Cells are in the shape of cubes
They provide mechanical support
Found in lining of kidney, ducts of salivary glands etc

4) Columnar Epithelial:
They are long and pillar like
 They are present in areas which require absorption and secretion
They form the lining of the stomach and intestines
They may occasionally form ciliated or glandular epithelium

2) Connective Tissues:
They are loosely spaces
Cells are floating in a matrix - fluid which may be jelly like, solid, or fluid depending on
the functions performed by the tissues
Matrix is excreted by the cell itself
All of them connect one body part to another
All of them have a stomata cells in the stomata
All of them have a variable amount of salt and fibre
They can be classified into four types:
1) Aerolar CT:
Location: Between skin and muscles, around blood vessels and nerves, in the
bone marrow
Function: Fills space inside organs, supports internal organs and helps in tissue
repair
Types:
-- Tendon : Connects muscles to bones
Tough - slightly elastic
Made up of Collagen fibres
-- Ligaments: Connect bones to bones
Very elastic - have considerable strength
Mainly composed of fibrin fibres

2) Adipose CT:
It is the fat storing tissues - its cells are lined with fat globules
Location: Beneat the skin, between internal organs and sometimes in the liver
Function: To act as an insulator and maintain body heat as well as to act as a
shock receptor and cushion the organs an bones

3) Solid CT (skeletal):
It has a solid matrix
-- Bone: Strong and non flexible
Matrix is composed of calcium and phosphorus
Forms a skeletal framework, protects organs in the body and anchors
muscles
-- Cartilage: Slightly less strong
Flexible
Matrix is formed of proteins and sugars
It smooths bone surfaces at joints
It is located between two bones
 Eg. Nose, Ears etc
5) Fluid CT (Vascular):
It has a fluid matrix
-- Blood: It transports food, gases, hormones and waste material throughout the
body
It moves both towards and away from the heart
It is red due to haemoglobin
It contains RBCs WBCs and plasma
-- Lymph: It transports proteins and intercellular fluids to the liver
It only moves towards the heart
It is of a milky colour due to fat droplets
It contains lymphotytes, few WBCs, and plasma

3) Muscular Tissues:
They are soft, contractile tissues
They are mostly attached to bones
they help in the movement of the body
They are of three types:
1) Striated Muscles:
Structure: They are cylindrical, multinucleated, with light and dark bands and no branching
Function: They help with the movement of the body and fill spaces near holes
Location: Muscles of leg, arms, back, shoulders,
They work at different speeds, tire easily and require frequent rest
2) Non Striated (Smooth) Muscles:
Structure: Spindle shaped, uninucleated, no light and dark bands, no branching
Function: Perform various function depending on location ; food digestion, blood circulation,
passage of blood through arteries and vein
Location: iris of the eye, uterus, food pipe, walls of stomach and intestine
They work at fixed speeds, don't tire easily and do not require long rest
3) Cardiac:
Structure: Long cylindrical, uninucleated, with light and dark bands and branching
Functions: To show contractions and relaxations throughout the organs life
Location: Only the heart
They do not tire, they do not need rest

4) Nervous tissue
It comprises nerve cells called neurons
Structure: It has a cell body called the cyton out of which emerges a long tail called the axon
Function: It conducts nerve impulses between the brain and different organs. Nerve receptors
help process the environment and then produce a suitable response. Eg. Nerve receptors in the
nose help detect smell
Location: Brain, Spine, Nerves