Introduction of Tissue
The word tissue is derived from the English word "tissu". This is a past participle of the verb tisser which means "to weave". The branch of science which deals with the study of tissues is known as "histology" or in case it is studied with the interconnection of disease is known as histopathology.
Definition of Tissue
Tissue can be defined as" The biological organisational level between the cells to form a complete organ is termed as tissue." These are generally a group of similar cells with their extracellular material.
Types of Tissues
Tissues are broadly classified into two types :
Plant tissue
Animal tissue
Let us discuss both the tissues in detail.
Plant Tissue:
The plant tissues are further broadly classified into three types. Those are:
Epidermis tissue
Vascular tissue
Ground tissue
Epidermis Tissue: These tissues are the cells that build up the outer surface of the leaves and the young plant body.
Vascular Tissue: This tissue is further made up of two primary components namely the xylem and phloem. These components are used to transport fluids and nutrients internally in a plant
Xylem:
The xylem consists of four kinds of cells which include the tracheids, vessels, xylem fibres or xylem parenchyma.
These are the main parts to transport minerals into the vascular system.
Phloem:
The phloem mainly consists of a sieve tube, companion cell, phloem fibre, phloem parenchyma.
This part is very essential to the plant as it comprises the plumbing system to the plant.
Ground Tissue:
The function of these tissues is to store reserved nutrients. It also manufactures nutrients by photosynthesis.
Animal Tissue:
These tissues are further broadly classified into four categories. Those are :
Connective tissue
Nervous tissue
Epithelial tissue
Muscle tissue
Let us discuss the tissues in detail.
Connective Tissue: These types of tissues are generally fibrous tissues made up of non-living material, known as extracellular cell matrix. These matrices can be liquid or rigid.
Nervous Tissue: The central nervous system and the peripheral nervous system combine to comprise the nervous tissue. In the central nervous system, the neural tissues present make the brain and spinal cord. On the other hand, the peripheral nervous system comprises the cranial nerves and spinal nerves.
Epithelial Tissue: These tissues comprise the cover tissues of a body. These tissues include the skin, the airways, surfaces of soft organs, the reproductive tract, and the inner lining of the digestive tract.
Muscle Tissue: These tissues make the visceral or smooth muscles that are found in the inner lining of the organs. These tissues are also found in the heart.
FAQs on Tissue
1. What is meristematic tissue?
These are the tissues that are completely dividing rapidly and contribute to the increase in length and thickness of a plant. The meristematic tissues include three types of meristems. The cells when growing through the meristems are differentiated but when they further mature, they grow up to become the components of a plant.
These meristems include:
Lateral meristem
Apical meristem
Intercalary meristem
2. What do you mean by permanent tissue?
This tissue has a direct link with the meristematic tissue. When the meristematic tissue loses its ability to further divide and is given a particular place in the plant, then the tissue is termed as permanent tissue of the plant. These can be living or dead cells. The cells take up a permanent shape, size and function. This particular process is also known as cellular differentiation.
These are further broadly classified into two types:
Simple permanent tissue
Complex permanent tissue
3. Describe briefly the terms parenchyma, sclerenchyma and collenchyma.
Parenchyma, sclerenchyma and collenchyma are all the categories of the simple permanent tissue.
Parenchyma:
It consists of unspecialised living cells with thin cell walls and loose packing. The following structure provides intercellular spaces which are found in between cells of a tissue.
Sclerenchyma:
This particular cell comprises thick cell walls and dead cells along with negligible protoplasm. They do not have any intercellular spaces between them. They generally provide mechanical support.
Collenchyma:
These comprise generally thin walls but have thickening of cellulose along with pectin.
These are found mainly in monocots and the hypodermis of stems and leaves.
4. Describe the functions of the epithelial tissue.
The functions of the epithelial tissues can be listed as below:
Covering and lining of the free surface is the major function of epithelial tissue.
The cells of the epithelial tissue make the outer layer of the cell.
It majorly helps in the elimination of waste.
These tissues are generally used to secrete enzymes and hormones in the form of glands.
5. Describe some types of common epithelium tissue.
Some of the common epithelial tissues can be listed as described below:
Simple squamous epithelium
Simple cuboidal epithelium
Simple columnar epithelium
Simple ciliated columnar epithelium
Simple glandular columnar epithelium
Stratified keratinized epithelium
Stratified non keratinized squamous epithelium
Simple transitional epithelium
6. Explain the Functions of Epithelial Tissues.
The functions of epithelial tissues can be listed below.
The principle functions of epithelial tissue include covering and lining of free surface
Inside the body, the epithelial cells from the lining of the alimentary canal and mouth protect these organs
The body surface cells form the outer layer of skin
Epithelial tissues help in the waste elimination
They help in the absorption of nutrients and water
A few epithelial tissues perform secretory functions. They also secrete a variety of substances including saliva, sweat, mucus, enzymes, and more
Epithelial tissues secrete hormones and/or enzymes in the form of glands
7. Give a Summary of Plant Tissues.
A summary of plant tissue can be listed below.
Three plant cell types are found in each of the major plant tissues: ground, dermal, and vascular tissues
The ground tissues make up most of the interior parts of a plant. It carries out the basic metabolic functions and stores water and food
Dermal tissue covers the outside parts of a plant in a single layer of cells known as the epidermis. It also mediates the majority of the interactions between a plant and its environment
Vascular tissue runs through the ground tissue that is present inside a plant. It consists of bundles of phloem and xylem, which transport water, food, and minerals throughout the plant
