TISSUES - Study Notes (Std.9th)

 

TISSUES

 Tissue – A group of cells that are similar in structure and work together to achieve a particular function.

 Group of cells                                   Function

1)    Muscle cells                                  helps in movement as they contract and relax

2)    Nerve cells                                    carry messages

3)    Blood cells                                   carry oxygen, food and other substances

4)    Vascular tissue                                      conducts water and food.

 

PLANT TISSUE	ANIMAL TISSUE
1)    Plants are stationary. They don’t move. 2)    Tissues of the plants are supportive. 3)    They provide structural strength. 4)    Most of the tissues are dead. As they provide mechanical support and require less maintenance.	1)    Animals move around from one place to another. 2)    These require more energy compared to plants. 3)    Most of the tissues in animals are living.

 

PLANT TISSUES

Two types of plant tissues

1)    Meristematic tissue                                2) Permanent tissue

 

1)    Meristematic tissue

These are growing tissues (Dividing tissue)

·        Apical meristem – present at the tips of stem and roots.

·        Lateral meristem – present at the girth of stem or roots.

·        Intercalary meristem – present at the base of the leaves or internodes on twigs.

2)    Permanent tissue

Meristematic tissues lose their ability to divide, take up a specific role and form a Permanent tissue

 

Ø Differentiation – A cell taking up a permanent shape, size and function is called differentiation.

 

§  Simple permanent tissues

Made up of one type of cell.

¨     Parenchyma

These are formed by basic packing of few layers of cells.

They provide support to the plant and stores food.

¨     Chlorenchyma

          They contain chlorophyll and perform photosynthesis.

 

¨     Aerenchyma

          These tissues contain large air cavities which give buoyancy to the plants and help them to float.

¨     Collenchyma

          These provide flexibility. They help in easy bending of some parts of plants without breaking.

¨     Sclerenchyma

          These tissues make the plant hard and stiff. Cells of these tissues are dead. Eg. Husk of coconut.

Epidermis – The outer most layer of the cell.

i.            In dry habitat epidermis is thick to protect the loss of water.

ii.            Epidermal cells of aerial plants secrets wax like material. This protects the loss of water, mechanical injury and invasion of parasitic fungi.

Note – epidermal cells forms a protective layer, so there is no intercellular space between the cells.

Stomata – small pores in the epidermis of the leaf.

Guard cells – two kidney shaped cells which encloses stomata.

Functions of stomata

a.     Exchange of gases with the atmosphere

b.     Transpiration

§  Complex permanent tissue

These are made up of more than one type cells.

Vascular tissues – XYLEM AND PHLOEM

 

XYLEM – this consists of

·        Tracheids and Vessels – this helps to transport water and minerals vertically.

·        Xylem parenchyma – helps to store food and sideways conduction of water.

·        Xylem fibres – these provides support.

 

 PHLOEM – this consists of

Sieve tubes, Companion cells, Phloem fibres, Phloem parenchyma

Phloem transports food from leaves to other parts of plants.

ANIMAL TISSUES

Types of animal tissues

1)    Epithelial Tissue                 2) Connective Tissue

3)   Muscular Tissue                4) Nervous Tissue

 

1)    Epithelial Tissue (Covering tissues)

Present at

Skin                                          Lining of mouth

Lining of blood vessels            Lungs alveoli

Kidney tubules

 

Types of Epithelial tissues

i.            Squamous Epithelium – Simple flat kind of tissues where transportation of substances takes place through selectively permeable surface of cells.

Lining of blood vessels and alveoli.

These are simple squamous epithelium

In skin, the epithelial tissues are arranged in pattern of layers.

These are called stratified squamous epithelium.

ii.            Columnar Epithelium – These tissues functions absorption and secretion. These are present in the inner lining of intestine, respiratory track.

iii.            Cuboidal epithelium – these tissues provide mechanical support. These are present in the lining of kidney tubules and ducts of salivary glands.

2)    Connective Tissue

Loosely packed cells are embedded in the intercellular matrix.

Tissue Blood

Matrix Plasma

Function Transports gases, digested food, hormones and waste materials to different parts of body.

Tissue Bone

Matrix Hard calcium and phosphorous compounds

Function Forms the framework and supports the organs of the body

Tissue Ligament

Matrix  Very less matrix

Function  Elastic tissue which connects bones.

Tissue Tendons

Function  Fibrous tissues which connects muscles to bones.

Tissue Cartilage

Matrix  Solid matrix of proteins and sugars

Function  Smoothens the bone surfaces at joints

Tissue Areolar

Function Fills the space inside the organs, supports the internal organs and helps in repair of tissues.

Tissue Adipose

Function Stores fats and acts as an insulator

 

3)    Muscular Tissue

VOLUNTARY MUSCLES	INVOLUNTARY MUSCLES
These muscle moves as per our will.   These are present in our limbs	These muscles won’t moves as per our will. Tissues present alimentary canal, blood vessels

 

Voluntary muscles show alternate light and dark bands when stained, so they are called as striated muscles.

Involuntary muscles are called as unstriated muscles.

Involuntary muscles of heart are called as Cardiac muscles.

 

4)    Nervous Tissue

These cells have ability to respond to stimuli.

The Brain, Spinal cords and Nerves are composed of nervous tissue.

Cells of nervous tissue are called as Nerve cells or Neurons.

Nerve cell consists of nucleus and cytoplasm with a long part Axon and short branched parts called Dendrites.

 

 

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