Tissues Class 9 Notes

Right from the time we are made familiar with the functioning of the human body, we have always been taught the importance and uniqueness of every organ that the human body has. But have you ever thought about how these organs are made? The basic element via which every organ of the living body is made is called Tissues. Thus, in simpler terms, the accumulation of tissues forms an organ both in plants and animals. The Class 9 NCERT book contains a very comprehensive chapter on Tissues which elucidates various types and functioning of tissues. Through this blog, we aim to present detailed tissues class 9 notes.  

What are Tissues?

We have already studied in the fundamental unit of life class 9 notes that the tissues are composed of cells. Cells individually cannot perform all the tasks of an organism. Hence, cells group together to form functional organs known as tissues. Muscles, organs and blood are all tissues formed by the grouping of cells. The cells of a single tissue have the same structure and perform a common function. We will look at the distinct type of tissues present in the plant and animal body in the tissues class 9 notes.

Plant Tissue

Plant tissues are generally non-moving tissues. The plant tissues are commonly made up of dead cells as they have to ensure that the plants have mechanical strength. The tissues present in the growing parts of the plant are not made up of dead cells. Also, the tissue structure is not specialized. Let’s take a look at the tissues class 9 notes to know more about the different types of plant tissues:

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Meristematic Tissue

The tissues located in the growing parts of plants are known as Meristematic Tissues. These tissues have a very thin cellulose wall and can divide themselves and form new tissues. They are further divided into apical, lateral and intercalary. The types of meristematic tissues are:

• Apical: Located at the stem and roots’ growing tip.
• Lateral: Meant for girth and located under the tree bark.
• Intercalary: Present at leaf internode or base

Permanent Tissue

Part of the tissues class 9 notes, these tissues are made up of dead cells and perform roles such as giving structural strength to the plant. These tissues do not divide and form more cells as meristematic tissues do. In the chapter tissues class 9 notes, majorly, we will discuss two types of permanent tissues, i.e, Simple and Complex. Simple permanent tissues are Parenchyma, Chlorenchyma, Aerenchyma, Collenchyma and Sclerenchyma, on the other hand, main complex tissues are Phloem and Xylem. 

Simple Tissues

• Parenchyma: These are tissues made up of living cells. These cells are loosely packed and long, and are meant to impart support to the body of the plant. Additionally, they can also store nutrients. Chlorenchyma and Aerenchyma are two types of Parenchyma.
  Chlorenchyma contains chlorophyll and these tissues perform the essential task of photosynthesis.
  Aerenchyma are present in aquatic plants and give them a buoyant nature.
• Collenchyma: The primary location of these tissues are under the epidermis of the leaf and the stem of the plant. They are tightly packed and elongated and meant to provide both strength and flexibility to the plant.
• Sclerenchyma: These tissues are made up entirely of dead cells. The primary location of these tissues is the leaf veins and seed coverings. They provide strength to the plant and make it hard.
• Protective: These tissues are the main outer layer of the plant. They are of two types: Epidermis and Cork. The epidermis is a continuous and tightly packed tissue which is meant for the protection of the inner organs of the plant. There is little to no intercellular spacing in this type of tissue. The cork tissue is the kind of tissue that is found in the bark of trees, and not in plants. This tissue is also made up completely of dead cells with no intercellular spacing. They protect the part of the plant from its external environment.

The food and water for the entire plant body is carried by the Phloem and Xylem. Let’s look at their descriptions in the tissues class 9 notes:

• Xylem: The xylem is made up of dead cells that have a very thick lining. It is made up of parenchymas, sclerenchyma, tracheids and the vessel. The tracheids and vessels of the xylem are broad in structure. Their main function is to help in the transportation of food and water vertically in the plants. The parenchyma is much like the tracheids and vessels, in that it helps in transportation of food and water in the plants, but horizontally. Lastly, the fibers of the xylem support other forms of transportation in the plant.
• Phloem: The phloem helps in the movement of food and water from the leaves post photosynthesis to other parts of the plant. The sieve tubes of the phloem are broad in shape and help in the transport of food in the plant. Companion cells of the phloem are meant to supplement the function of the sieve tubes, while phloem fibers impart structural flexibility to the plant. The starch and proteins of the plant are stored in the phloem parenchyma.

Stomata and Transpiration

The epidermis of the leaves of any plant contains microscopic, pore like structures which are known as stomata. The protection of the stomata is offered by kidney shaped cells which are known as guard cells. The guard cells are basically cells of the epidermis which have been modified in order to protect the stomata pores. Transpiration as well as exchange of gases through the stomata happens through the guard cells.

The evaporation of excess water from the plant through the stomata is known as transpiration. Transpiration plays a very important role in plants. It helps plants in the exchange of gases through the stomata, and also helps in regulating the temperature of the plant. It can also help in the upward transportation of food and water in the plants, contributing positively to their growth. 

Animal Tissue

In our tissues class 9 notes, the next important topic is of Animal Tissues. Animal tissues are generally moving and non-stationary. The tissues of animals are made up of cells that are living and are required to perform functions in the animal body. Animal tissues are hence also specialized in their structure. The growth of these cells is in all parts of the animal body, and therefore no dead cells are required, which do not grow. The main types of animal tissues are as follows:

Epithelial Tissue

The protective tissue of the body is known as Epithelial Tissues. Tissues such as the lining of the blood vessels, the skin of the animal, and kidney tubules are epithelial tissues. They separate the organs of the animal body from other organs and systems. The cells of the epithelial tissue are generally permeable, and there is no space between them. They carry a thin membrane over them to separate them from other tissues. The following are the types of epithelial tissues:

• Simple Squamous: Blood vessel linings as well as lung alveoli linings are this type of tissue. This is a soft tissue that is very sensitive.
• Stratified Squamous: The main example of this type of tissue is the skin. They are generally multi-layered.
• Cuboidal: Salivary ducts and kidney tubules are generally cuboidal in shape. They are meant for absorption as well as secretion. 
• Columnar: These are present in the intestine lining and the respiratory tract.  

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Connective Tissue

The next important mention in our tissues class 9 notes is this type of tissue. The connective tissues are present in the cellular matrix and perform the job of connecting one organ of the body to another. Connective tissues can be rigid, dense, or fluid. The best example of connective tissue is the blood in the human body. It transports gases, waste, hormones, and nutrients throughout the body. Each organ needs blood to keep functioning. The Red Blood Cells (RBC) carry oxygen; the White Blood Cells (WBC) help protect against diseases while platelets help in the clotting of blood. The joints of bones are connected by cartilage, which also provides them with protection. 

On the other hand, the ligaments are meant to combine individual bones together to form the skeleton, while tendons connect bones and muscles in order to prevent misalignment. A special type of tissue is areolar tissue, which is present in the spaces inside the organs. These help repair organ tissues.

Blood

Blood is a type of connective tissue whose function is the transportation of gases, food stuff, hormones and waste materials inside the body. Blood consists of three main types of cells, which are red blood cells, white blood cells and platelets. The red blood cells have a pigment known as haemoglobin, which helps in the transportation of oxygen to various parts of the body. The main function of white blood cells and platelets is to fight diseases and clot blood in cases of injury, respectively. 

Similar to blood is a tissue known as the lymph. Much like blood, there is a network of lymph nodes throughout the body. The lymph consists only of white blood cells. It contains more amounts of glucose than the blood, but less proteins and calcium. The lymph does not need to be pumped and flows in only one direction. Let us also discuss the different types of connective tissue in our tissues class 9 notes. These are:

• Plasma: The plasma is a connective tissue that contains the red blood cells, white blood cells and platelets. It is primarily a fluid matrix that is present inside the blood. The proteins and hormones of the blood are also present in the plasma.
• Bones: The bones are the basic structure of the body, over which various tissues and organs are wrapped and supported. Bones are inflexible and composed of calcium and phosphorus.
• Ligaments: Bones are connected together through ligaments. They have a minimal matrix and are flexible tissues.
• Tendons: Bones and muscles are connected together through tendons. The tendons are tissues that are not very flexible but are some of the most strong tissues in the body. 
• Cartilage: Cartilages are present at the joints of bones. They have a smooth structure. They are basically a homogenous matrix formed of proteins and sugars. A number of body parts are provided support by the cartilages.
• Areolar: This type of tissue causes tissue repair and fills inter-organ space. Their main locations are skin, muscles, blood vessels, etc.
• Adipose: The tissue located in the space between the internal organs and the skin is known as the adipose tissue. It is an insulator and stores fat.

Muscular Tissue

Muscular tissue is another important animal tissue that we will explain in our tissues class 9 notes. It consists of muscle fibres which are a type of elongated cells responsible for our body movements. Special proteins, known as contractile proteins help the muscle to contract and relax, thereby causing movement. Muscles are of three types:

• Voluntary muscles: These are the muscles that we can move according to our will. These are also known as skeletal muscles or striated muscles.
• Involuntary muscles: Also known as smooth muscles, these do not move according to our will. Such muscles are found in the iris, bronchi and ureters of th human body.
• Cardiac muscles: These are special kinds of muscles that do not fit into any of the other categories. They perform contraction and relaxation in rhythm. These muscles are formed of individual cells that are connected by intercalated discs, and hence can work as a uniform organ.

Nervous Tissue

The tissues that are composed of a mixture of cells and neurons are known as Nervous Tissues. Neurons are the primary connectors that help the animal react to stimuli. Neurons help the body respond to external stimuli through electrical signals. Instead of the neurons themselves traveling, they transfer the signals from one neuron to the other, which helps transfer the signal at a considerably faster pace. 

The structure of the neuron consists of dendrites at the head of the neuron. The dendrites are branched structures that increase the neuron’s surface area and help the neuron capture a large amount of information from the surroundings. The cell body of the neuron is known as the soma, which does not play a function in signal transmission but produces proteins so that the neuron keeps working. The axon connects the body to the end of the neuron and helps in signal transmission. 

We hope that you found this blog on tissues class 9 notes useful in understanding the functioning of various animal and plant tissues. Confused about which path to choose for your future studies? Reach out to our experts at Leverage Edu for the best guidance in choosing the perfect career as per your interests and career goals. Sign up for a free session today!