A group of cells that are comparable in design and work together to do an impossible to miss work is called tissue.
Tissues give underlying strength, mechanical strength, show division of work.
The types of simple tissues are Parenchyma, Collenchyma, Sclerenchyma and Aerenchyma.
The husk of coconut is made of sclerenchymatous tissue.
Phloem consists of four kinds of components: strainer tube, partner cells, phloem filaments and phloem parenchyma.
1. Muscular tissue, 2. Nervous tissue, a mix of both tissues are important for development in our body.
A neuron comprises a cell body with a nucleus and cytoplasm, from which long thin hair-like parts emerge. Every neuron has a solitary long part called the axon, and some little, short expanded parts called dendrite. An individual nerve cell is known as a neuron, it very well might be up to a meter long.
Features of cardiac muscles
(1) Heart muscles (cardiovascular muscles) are round and hollow, stretched and uninucleated.
(2) They are striated muscle fibres.
(3) They are compulsory muscles, and can't be constrained by us.
Areolar tissues are connective tissues found in animals. It is found among skin and muscles, around veins and nerves and in the bone marrow.
It occupies the space inside the organs, upholds inner organs and helps in the maintenance of tissues.
A group of cells that are comparable in design and work together to do an impossible to miss work is called tissue.
(a) Squamous epithelium
(b) Tendons
(c) Phloem
(d) Areolar tissue
(e) Blood
(f) Nervous tissue
(a) Skin—Stratified squamous epithelium
(b) Bark of tree—Cork, protective tissue
(c) Bone—Connective tissue
(d) Lining of kidney tubule—Cuboidal epithelium tissue
(e) Vascular bundle—Conducting tissue
In the essence of the roots and stems. At the point when it contains chlorophyll, it is called chlorenchyma, found in green leaves. In aquatic plants, parenchyma contains enormous air cavities and assists them with drifting. This kind of parenchyma is called aerenchyma.
Cells of epidermis structure a constant layer without intercellular spaces. It secures every one of the pieces of plants.
Cork goes about as a defensive tissue since its cells are dead and minimalistically orchestrated without intercellular spaces. They have testimony of suberin on the dividers that make them impenetrable to gases and water.
The xylem is composed of vessels, tracheids, xylem fibres and xylem parenchyma.
Simple tissues are composed of one kind of cells which facilitate playing out a typical capacity.
Complex tissues are composed of more than one sort of cell. Every one of these arranges to play out a typical capacity.
Parenchyma: The cells have slight cell dividers composed of cellulose.
Collenchyma: The cells have cell dividers thickened at the comers because of the gelatin statement.
Sclerenchyma: Their dividers are thickened because of lignin testimony.
Stomata is a mouth-like opening in the leaf surface it helps in evacuation of excess water and helps in admission of oxygen structure to the external climate which helps in photosynthesis. It opens when there is need to eliminate water or to take oxygen and yet monitor cells shuts the sonar when there Is no need of product and oxygen.
Three type of muscle fibres: Striated muscles, Smooth muscles, Cardiac muscles
(1) Cardiac muscles cells are round and hollow, fanned and uninucleated.
(2) They are compulsory muscles.
(3) They show musical withdrawal and unwinding all through life.
(4) Their musical withdrawal and unwinding helps in siphoning the heart.
| Striated muscles | Unstriated muscles | Cardiac muscles |
|---|---|---|
| 1. The cells of striated muscles are long, cylindrical, unbranched and multinucleate. | 1. The cells of unstriated muscles are long and pointed at the ends, spindle shaped and uninucleate. | 1. The cells of cardiac muscles are cylindrical, branched and uninucleate. |
| 2. Many nuclei which are situated towards the periphery of muscle fibre. | 2. The cells have only one nucleus situated in the center. | 2. Each cell contains one or two nuclei situated in the center. |
A thick layer of subcutaneous fat prevents heat loss from the body. It works as an insulating coat to keep the animal body warm in a colder environment. This layer serves as reserve food for adverse conditions. Thus, animals of colder regions and fish of cold water have thicker layers of subcutaneous fat.
(A) (B)
(a) Fluid connective tissue (v) Blood
(b) Filling of space inside the organs (iv) Areolar tissue
(c) Striated muscle (iii) Skeletal muscle
(d) Adipose tissue (i) Subcutaneous layer
(e) Surface of joints (ii) Cartilage
(f) Stratified squamous epithelium (vi) Skin
(A) (B)
(a) Parenchyma (i) Thin walled, packing cells
(b) Photosynthesis (ii) Carbon fixation
(c) Aerenchyma (iv) Buoyancy
(d) Collenchyma (iii) Localized thickenings
(e) Permanent tissue (v) Sclerenchyma
In a potted plant, the water evaporates through the stomata present on leaf by the process of transpiration. These water vapours reach to the wall of the glass jar and condense to form water droplets.
Different components of xylem are tracheids, vessels, xylem parenchyma and xylem fibres. Xylem parenchyma is the only living component of xylem whose diagram is drawn below:
Different elements of phloem are sieve tubes, companion cells, phloem fibres and phloem parenchyma. Different phloem elements are shown in the following diagram:
In Fig.
A. Sieve tube with compion cell.
B. Phloem parenchyma C,D. Phloem fibres
(a) True
(b) True
(c) False
(d) True
(e) False
Voluntary muscles are the muscles which are under the control of our will e.g. skeletal muscles. Muscles present in our limbs (arms and legs) are skeletal muscles and can be moved by our conscious efforts not under the control of our will, e.g., smooth muscles and cardiac muscles. Muscles present in the stomach, intestine etc. are smooth muscles and muscles present in our heart are cardiac muscles, which cannot be moved by our conscious efforts.
(a) V
(b) I V
(c) V
(d) I V
(a) squamous epithelium
(b) columnar epithelium
(c) cuboidal epithelium
(d) respiratory tract
Water hyacinth (Eichhornia crassipes) floats in water due to presence of large air cavities in the parenchyma tissue. These specialized parenchyma tissues are called aerenchyma.
Epidermis is the outermost protective layer formed by parenchymatous cells having no intercellular spaces. The cells of epidermis secrete an ethic waxy layer known as cuticle on the outer surface which is water resistant and prevents mechanical injury and invasion of parasites.
(a) suberin
(b) Sieve tubes
(c) inorganic, organic substances
Epidermis present on the outer surface of the entire plant body. The cells of the epidermal tissue form a continuous layer without any intercellular space. The epidermis performs the following important functions are ;
i. Epidermis is a protective tissue of the plant body.
ii. It protects the plants against mechanical injury.
iii. It allows exchange of gases through the stomata.
iv. Epidermal root hairs help in absorption of water.
(a) Xylem and phloem
(b) Stomata
(c) suberin
(d) sclerenchyma
(e) Collenchyma
(f) Xylem; phloem
(g) water; minerals
(h) food; leaves
| Parenchyma | Sclerenchyma |
|---|---|
| a. These cells consist of thin cell walls made up of cellulose. | a. These cells consist of thick and lignified cell walls. |
| b. It is made up of living cells. | b. It is made up of dead cells. |
| c. Cells are usually loosely packed with large intercellular spaces. | c. No intercellular spaces occur between the cells. |
| d. It is primarily a storage tissue and stores nutrients and water in stem and roots. | d. It is primarily a mechanical tissue and provides mechanical strength to the plant part It is primarily a storage tissue and stores nutrients and water in stem and roots. |
| e. These are cells found in soft parts of plants such as leaves, fruits. | e. These cells are found in mature part of the plant like herbaceous and woody plants. |
In fig. A. T.S. Sclerenchyma B. T.S. Parenchyma
Types of Epithelial Tissue: Depending upon the shape and function of the constituent cells, epithelial tissues are of following types:
Squamous epithelium: The squamous epithelium is made of a single thin layer of flattened cells with irregular boundaries. They are found in the walls of blood vessels and air sacs of lungs and are involved in functions like forming a diffusion boundary.
Columnar epithelium: The columnar epithelium is composed of a single layer of tall and slender cells. Their nuclei are located at the base. Free surfaces may have microvilli. They are found in the lining of the stomach and intestine and help in secretion and absorption.
Cuboidal epithelium: Cuboidal epithelium is composed of a single layer of cube like cells. This is commonly found in duvets of glands and tubular part of nephrons in kidneys and its main functions are secretions and absorption. The epithelium of proximal convoluted tubules (PCT) of nephrons in the kidney has microvilli.
Ciliated epithelium: If the columnar or cuboidal cells bear cilia on their free surface they are called Ciliated epithelium. Their function is to move particles or mucus in a specific direction over the epithelium. They are mainly present in the inner surface of hollow organs like bronchioles and fallopian tubes.
Glandular epithelium: Some of the columnar or cuboidal cells that specialized for secretion and are called glandular epithelium.
Stratified epithelium: This is a compound epithelium in which cells are arranged in many layers one above the other. It is found in places where there is much wear and tear, such as the epidermis of skin, lining of the mouth cavity.
The three main types of muscular tissues found in human body are :
(i) Skeletal (striated) muscle tissue
(ii) Smooth (Non striated) muscle tissue
(iii) Cardiac muscle tissue.
The well labelled diagrams of these tissues are as follows:
(a) Meristematic cells have a prominent nucleus and dense cytoplasm because they have to divide continuously as they are in the state of metabolic division. These cells do not store food material and waste so they lack vacuole in them.
(b) Due to lignification in the sclerenchyma cells, the cells compactly arranged and leaves no intercellular space between them.
(c) Pear fruit contains sclerenchymatous stone cells or sclereids which provide gritty texture to the fruit. Thus, when we chew pear fruit, we get a crunchy and granular feeling.
(d) Collenchyma tissue provides mechanical support and flexibility to the growing parts of the plant such as the young stem and petiole of a leaf. This allows their easy bending without breaking. Thus the branches move and bend freely in high wind velocity.
(e) The husk of a coconut is made up of sclerenchymatous fibres which consist of compactly arranged cells with thick lignified cell walls and no intercellular spaces. So, they are tightly joined together. Thus, it is difficult to pull out the husk of a coconut.
Characteristics of cork are as follows:
As plants grow older, a strip of secondary meristem replaces the epidermis of the stem. Cells cut on the outer side by this meristem are called cork.
Role of cork is as follows:
Xylem and phloem are known as complex tissues as they are made up of more than one type of cells. These cells work in a coordinated manner, as a unit, to perform the various functions of the xylem and phloem. Differences between xylem and phloem are:
| Xylem | Phloem |
|---|---|
| a. In addition to conduction, xylem provides mechanical strength to the plant. | a. Phloem performs no mechanical function for the plants. |
| b. It conducts water and minerals. | b. It conducts organic solutes or food materials. |
| c. Most of the components of xylem except xylem parenchyma are dead cells. | c. Most of the components of phloem except phloem fibres are living cells. |
(a)
| Meristematic Tissue | Permanent Tissue |
|---|---|
| a. It provides growth to the plant. | a. It provides protection, conduction photosynthesis, storage etc. |
| b. Cells of this tissue do not contain crystals and other inclusions. | b. Cells of this tissue possess crystal and other inclusions. |
| c. Cells of this tissue are very active, have dense cytoplasm, thin walls and prominent nuclei. They lack vacuoles | c. Cells of this tissue are vacuolated, vary in shape and size. Their cell walls may be thin or thick. |
| d. Cell wall of its cells is thin and elastic. | d. Cell wall of its cells may either be thin or thick. |
| e. Cells of this tissue are living. | e. Cells of this tissue may be living (parenchyma) or dead (sclerenchyma). |
| f. Intercellular spaces are absent in cells. | f. Intercellular spaces may be present or absent. |
(b) Differentiation is the process in which unspecialised cells lose their ability to divide and convert into specialised cells and take up permanent shape, size, structure and function.
(c)
Simple permanent tissues:
(i) parenchyma
(ii) collenchyma
(iii) sclerenchyma
Complex permanent tissues:
(i) xylem
(ii) phloem
