Key Types of Tissue and Their Roles
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 What Is Tissue in Biology?
1. What exactly is a tissue in biology?
In biology, a tissue is a group of similar cells that work together to perform a specific function. Think of them as the building blocks of organs. For example, muscle tissue is made of muscle cells that contract to cause movement, and nervous tissue is made of nerve cells that transmit signals.
2. What are the main types of plant tissues?
Plant tissues are broadly divided into two main types based on their ability to divide:
- Meristematic Tissues: These are growing tissues with cells that actively divide, helping the plant to grow in length and girth. They are found in the tips of roots and stems.
- Permanent Tissues: These tissues are formed from meristematic cells that have lost the ability to divide and have taken on a specific role. They are further classified into simple and complex tissues.
3. What are the four major types of animal tissues?
The four primary types of tissues found in animals, including humans, are:
- Epithelial Tissue: Forms protective coverings and linings for organs and cavities. Skin is a key example.
- Connective Tissue: Supports, connects, or separates different types of tissues and organs. Examples include bone, cartilage, and blood.
- Muscular Tissue: Composed of cells that can contract, enabling movement.
- Nervous Tissue: Made of nerve cells (neurons) that transmit electrical signals, forming the brain, spinal cord, and nerves.
4. What is the difference between simple and complex permanent tissues in plants?
The main difference lies in their cell composition. Simple permanent tissues, like parenchyma and sclerenchyma, are made up of only one type of cell. In contrast, complex permanent tissues, such as xylem and phloem, are made of more than one type of cell that work together as a unit to transport water, minerals, and food.
5. Why is blood considered a connective tissue even though it is a fluid?
Blood is called a connective tissue because it fits the definition: it has cells (red blood cells, white blood cells) suspended in an extracellular matrix (the plasma). Its primary function is to connect different parts of the body by transporting oxygen, nutrients, hormones, and waste products, which is a key role of connective tissues.
6. How does the structure of a neuron help it perform its function?
A neuron, or nerve cell, is specially designed for communication. It has a main cell body, dendrites that receive signals, and a long axon that transmits signals to other cells. This elongated structure allows it to send electrical and chemical messages quickly over long distances within the body, coordinating everything from muscle movement to thoughts.
7. Why do plants have tissues made of dead cells, like sclerenchyma?
Plants use tissues made of dead cells, like sclerenchyma, for strength and support. The cell walls of sclerenchyma are very thick and hardened with a substance called lignin. When the cells die, they leave behind these hard, rigid walls, which provide mechanical strength and stiffness to the plant, helping it stand upright and withstand environmental stress.
