Tissues Class 9 CBSE Notes

Tissue
Tissue

Tissues are a collection of cells with a shared origin and similar function.

A. Plant tissues:

Plant tissues are classified into two groups based on their ability to divide:

  • Meristematic tissues
  • Permanent tissues

1. MERISTEMATIC TISSUES

Meristematic tissues are made up of cells that are actively dividing. Meristematic tissues are divided into three categories:

Apical meristem:

At the growing tips of stems and roots, this fungus can be found. The purpose of this function is to lengthen the stems and roots.

Intercalary meristem (intercalary meristem):

It can be found near the base of leaves or at the internodes. Important function: For plant growth in the long run.

Lateral meristem:

The lateral sides of the stems and roots are covered in this fungus. Increase the thickness of stems and roots, which is an important function.

2. Simple Permanent tissues:

The cells in the tissue, which are formed from meristematic tissues, lose their ability to divide. Permanent tissues are split into two groups:

Simple permanent tissue is made up of only one cell type.

Simple permanent tissues are divided into the following categories:

Parenchyma:

Intercellular space, which is found in the soft portions of the plant, is made up of unspecialized living cells with relatively thin cell walls. Storage is their primary role.

Collenchyma:

Living and elongated cells with irregularly thickened cell walls at the comers. There is no spacing between cells. It gives the plant mechanical support and flexibility. It aids in the bending of stems and leaves.

Sclerenchyma:

Long, thin, and thick-walled cells make up this organism. There are no intercellular gaps in this tissue since it is made entirely of dead cells. Sclerenchyma cells are dead cells found in seeds, nuts, coconut husks, jute fibres, and other materials.

Complex permanent tissue:

It’s made up of a variety of cell types (Conducting tissues.)

Types of complex permanent tissues:

Xylem: 

Transports water and minerals from the roots to the plant’s various sections.

Tracheids, vessels, xylem parenchyma, and xylem fibres are the four types of cells that make up the xylem.

Phloem:

Phloem transports nourishment from the leaves to the various components of the plant.

Sieve tubes, companion cells, phloem parenchyma, and phloem fibres are the four types of cells that make up the phloem.

Protective Tissue:

Protective Tissue

A single layer of cells makes up protective tissue. Consider the epidermis. Stomata are found on the leaf’s epidermis.

Animal Tissues

Epithelial Tissues

On the outer layer of a body or organ surface, epithelial tissues can be visible. Most animals’ outermost protective layer is made up of these.

Squamous Epithelium

Squamous epithelium is a tissue layer that is exceedingly thin and flat. They’re semi-permeable, making them ideal for gas exchange. They can be found in the oesophagus and mouth linings.

Cuboidal Epithelium

They are cuboidal in shape and form the lining of salivary glands and kidney tubules, as their name suggests. They offer mechanical assistance. When they develop glands, they also form glandular epithelium.

Columnar Epithelium

The lining of the intestines, for example, is made up of these tissues that help in absorption and secretion. They are made up of cells that are elongated. When these cells have cilia, they form ciliated columnar epithelium, similar to that found in the respiratory system.

Stratified Squamous Epithelium

Multiple layers of squamous epithelium are organised in a pattern to generate this type of tissue. This is the type of tissue that makes up our skin.

Muscular Tissue

Our muscles are made up of these tissues, and they are responsible for practically all of the body’s actions.

Striated/Skeletal Muscles

The striated or skeletal muscles are responsible for all voluntary motions in our bodies. Because these tissues are usually linked to the bones, they are called skeletal tissues. They are multinucleated and long, cylindrical, unbranched with striations.

Unstriated/Smooth Muscles

Smooth or striated muscles are responsible for almost all involuntary motions in the body. They are uninucleate, long, smooth, spindle-shaped, and smooth. They can be found in the alimentary canal and blood vessels.

Cardiac Muscles

Our entire heart is made up of cardiac muscles. These muscles contract and relax in a rhythmic pattern that is involuntary. They resemble striated muscles in structure, but they are branching, uninucleate, and have intercalated discs.

Connective Tissues

These tissues aid in the connection of the body’s many parts. Blood, Bones, cartilages, tendons, ligaments, areolar tissues, and adipose tissues are all examples.

Nervous Tissue

The entire brain, spinal cord, and nerves of the body are made up of nerve tissue. All sensations, awareness, memory, and emotion are controlled by them.

Neurons

These are the cells that make up the nervous system as a whole. The cell body, axon, and axon terminals make up the cell.

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