2. Cells are the body’s smallest functional units
they are grouped together to form tissues,
each of which has specialized functions,
eg.blood , muscle. Study of tissues is called
Histology.
What are tissues ?
Tissues are classified in two types:-
1) Plant Tissue
2) Animal Tissue
A group of cells having similar shape and
function act together to perform a specific
function is known as a tissue. All the body parts
are made up of tissues including the organs.
Groups of tissues make organs. Different types
of tissues are found in plants and animals.
3. 1. Plant Tissue
These tissues are found in plants. They are further divided into two parts which are:-
1.1 Meristematic Tissues -
These tissues are capable of cell division repeatedly. Meristematic tissues consists of Apical
Meristem, Lateral Meristem, Intercalary Meristem.
1.1.1 Apical Meristem -
They are present at growing tips of stems and roots.
Increases length.
1.1.2 Lateral Meristem -
Present on lateral sides of roots and stems.
Increases girth.
1.1.3 Intercalary Meristem -
Present at the base of leaves or internodes on twigs.
Increases the length of the organs.
4. 1.2 Permanent Tissues -
These are meristematic tissues which on maturing lose the ability to divide into specialised tissues.
They are divided into two types which are Simple Permanent Tissues and Complex Permanent
Tissues.
1.2.1 Simple Permanent Tissues -
They are made up of one type of cell. There are three types of Simple Permanent Tissues:-
Parenchyma
● The cells have an oval or
round shape.
● The cell wall is made up of
hemicellulose or cellulose.
● The cell is thin-walled.
● The cells have vacuoles and
very small nucleus.
● It is found in all parts of the
plant.
● The protoplasm is living and
dense
Collenchyma
● Cells are long and thick-walled.
● The cell wall is made up of cellulose
and pectin.
● It is the only tissue with the highest
refractive index due to the presence
of pectin.
● It is found in the epidermis and the
vascular bundle of dicot leaf.
● The amount of chloroplast is less in
the cells.
Sclerenchyma
● These are dead tissues,
very hard and rigid in
texture.
● Cells are thick-walled
with various size and
shapes.
● These provide
mechanical support and
rigidity to the plant.
5. 1.2.2 Complex Permanent Tissues -
They are made up of more than one type of cell. There are two types of Complex Permanent Tissues:-
Phloem
● It locates the prepared
organic food from the
leaves to different parts
of the plant.
● It is composed of sieve
tubes, companion cells,
phloem parenchyma, and
phloem fibres.
Xylem
● Materials move in one
direction only.
It provides support to the
plants.
● Transports water and
mineral salts from root to
other tissues
● It is composed of
tracheids, vessels, xylem
parenchyma, Xylem
fibres.
6. 2. ANIMAL Tissue
These tissues are found in animals. They are further divided into four parts which are:-
2.1 Epithelial Tissue -
It is the simplest tissue.
Protective tissue covering the entire animal body internally and externally.
It is divided into 4 types:-
i)Squamous
ii)Striated Squamous
iii)Cuboidal
iv)Columnar
7. 2.2 Muscular Tissue -
These are elongated cells called muscle fibres made up of contractile protiens.
These tissues are responsible for body movement.
It is consisted three types.
They are-
i)Striated
ii)Smooth
iii)Cardiac
8. 2.3 Connective Tissue -
These tissues connects and binds different tissues or organs.
Cells are loosely spaced and embedded in an intercellular matrix.
These tissues consists of 5 elements:-
2.3.1 Fluid
Helps in transportation of materials and provide defence.. It is consisted of two types
i)Blood - Fluid, slightly alkaline.
Transports digested food, gases, hormons and waste materials.
It consists of
Plasma - a fluid matrix in which blood cells are suspended. Contains proteins, hormones and salts.
Blood cells - contains RBC(Red Blood Cells), WBC(White Blood Cells) and Platelets.
ii)Lymph - straw colored fluid containing inorganic salts and organic compunds.
9. 2.3.2 Compact bone
It is divided into two types-
i) Tendon - connects muscles to bones.
Fiborous, great strength but limited flexibility.
ii) Ligament - connect two bones.
Elastic, contain very little matrix and have strength.
10. 2.3.3 Hyaline cartilage
It is divided into two types.
i) Cartilage - semi-rigid, flexible, matrix, made of collagen, sugar, protein.
Provide support and flexibility.
ii) Bone- Strong, inflexible, embedded in hard matrix composed of calicium and phosphorus compunds
Supports body, anchors muscles and supports organs.
11. 2.3.4 Areolar tissue
Areolar connective tissue is found between the skin and muscles, around blood vessels and
nerves and in the bone marrow. It fills the spaces inside the organs, supports internal organs and
helps in repair of tissues.
2.3.5 Adipose tissue
Fat-storing adipose tissue is found below the skin and between internal organs. The cells of this
tissue are filled with fat globules. Storage of fats also lets it act as an insulator.
12. 2.4 Nervous Tissue -
Cells of the nervous tissue are highly specialised for being stimulated and then transmitting the
stimulus very rapidly from one place to another within the body. The brain, spinal cord and nerves
are all composed of the nervous tissue. The cells of this tissue are called nerve cells or neurons. A
neuron consists of cell body with a nucleus and cytoplasm, from which long thin hair like parts
arise. Usually each neuron has single long part called the axon, and many short, branched parts
called dendrites.