TISSUES AND SUPPORTING SYSTEM
1. Definition of Tissue
A tissue is a group of similar cells that work together to perform a specific function in a living organism.
Examples of Tissues
Muscle tissue – helps in movement
Nerve tissue – transmits impulses
Supporting tissue – provides support, strength, and protection
2. Supporting System
The supporting system refers to the structures and tissues in plants and animals that provide support, shape, strength, protection, and aid movement.
In animals, the supporting system is called the skeleton.
In plants, support is provided by cell walls, vascular tissues, and strengthening tissues.
3. Types of Skeletons
There are three main types of skeletons in animals:
(a) Endoskeleton
Skeleton found inside the body
Made of bones and cartilage
Found in vertebrates (fish, amphibians, reptiles, birds, mammals)
Examples: Humans, dogs, birds, fish
Features:
Grows with the organism
Strong and flexible
Allows great body movement
(b) Exoskeleton
Skeleton found outside the body
Made of hard materials like chitin or calcium carbonate
Found in invertebrates
Examples: Insects, crabs, snails
Features:
Protects the body
Does not grow with the organism (must be moulted)
Provides attachment for muscles
(c) Hydrostatic Skeleton
Skeleton formed by fluid pressure within the body
Found in soft-bodied animals
Examples: Earthworm, jellyfish, hydra
Features:
Body fluid provides support
Allows flexibility and movement
4. Skeletal Materials
Skeletal materials are substances used in forming the supporting structures of organisms.
(a) Bone
Hard and strong skeletal material
Made of calcium phosphate and collagen
Found in vertebrates
Functions of Bone:
Support and shape the body
Protect vital organs
Enable movement
Produce blood cells
(b) Cartilage
Soft and flexible skeletal material
Found at joints, nose, ear, and trachea
Functions of Cartilage:
Reduces friction at joints
Provides flexibility
Acts as a shock absorber
(c) Chitin
Hard material forming exoskeleton of insects and crustaceans
Made of nitrogen-containing polysaccharide
Functions of Chitin:
Protection
Prevents water loss
Provides body shape
(d) Cellulose
Main skeletal material in plants
Found in plant cell walls
Functions of Cellulose:
Provides rigidity
Maintains plant shape
Prevents bursting of plant cells
5. Supporting Tissues in Plants
Plants do not have skeletons but are supported by specialized tissues.
(a) Parenchyma
Living cells with thin walls
Found in leaves, stems, roots
Functions:
Storage of food and water
Support when turgid
(b) Collenchyma
Living cells with thickened corners
Functions:
Flexible support
Allows bending without breaking
(c) Sclerenchyma
Dead cells with thick, lignified walls
Functions:
Strength and rigidity
Mechanical support
6. Functions of the Supporting System
The supporting system performs the following functions:
Support – Holds the body upright
Protection – Protects vital organs (brain, heart, lungs)
Movement – Works with muscles for locomotion
Shape – Gives definite shape to the body
Strength – Enables the body to withstand stress
Rigidity – Prevents collapse of body structures
Resistance to wind and water – Especially in plants
Attachment – Provides surfaces for muscle attachment
7. Importance of Supporting System
Enables growth and development
Enhances survival
Improves efficiency of movement
Provides structural stability
Conclusion
Tissues and the supporting system are essential for the survival of plants and animals. They provide support, strength, protection, and movement, ensuring proper functioning and stability of living organisms.