Tissue

TISSUES

MADE BY :AKHIL BANSAL

A group of cells that are similar in structure and/or work together to achieve a particular function forms a tissue.

WHAT IS A TISSUE?

PLANT TISSUES

MERISTEMATIC TISSUE

PERMANENT TISSUE

The growth of plants occurs only in certain specific regions. This is because the dividing tissue, also known as meristematic tissue, is located only at these points. Depending on the region where they are present , meristematic tissues are classified as apical, lateral and intercalary .

New cells produced by meristem are initially like those of meristem itself, but as they grow and mature, their characteristics slowly change and they become diff erentiated as components of other tissues.

MERISTEMATIC TISSUE

CLASSIFICATION

Apical meristem - Meristem at the tip of a plant shoot or root causes the shoot or root to increase in length. It is responsible for primary growth of plant.

Intercalary Meristem:  It is particularly common at the nodal regions. It may also occur at the base of the leaves. The intercalary meristem also contributes towards the increase in length as it brings about elongation of the internodal regions. It is also responsible for the formation of branches at the nodal regions.

Lateral Meristem: It appears in the mature tissues of roots and shoots. It helps in adding secondary tissues to the plant body and in increasing the thickness of stem of plants. Lateral meristem tissues are very active as they have dense cytoplasm, thin cellulose walls and prominent nuclei.

PERMANENT TISSUE

The cells formed by a meristematic tissue take up a specific role and lose the ability to divide. As a result, they form a permanent tissue. This process of taking up a permanent shape, size, and a function is called differentiation. Cells of meristematic tissue differentiate to form different types of permanent tissue.

Simple permanent tissue1. parenchyma

A permanent tissue of few layer of cells that forms the basic packing tissue.Consists of relatively unspecialized cells with thin cell walls Live cellsUsually loosely packed so that large spaces are there.Provides support to plants and also stores food.Parenchyma of stems and roots also stores nutrients and water.

ChlorenchymaIn some situations simple permanent tissue contains chlorophyll and performs photosynthesis then it is called chlorenchyma.

AerenchymaIs a parenchyma type of tissue found in aquatic plants with large cavities that give buoyancy to the plants to help them float.

2.collenchyma

A permanent tissue that gives flexibility to plants.Allows easy bending in various parts of a plant – leaf and stem, without breaking.

Provides mechanical support to plants.Found in leaf stalks (stem or main axis) below the epidermis (outermost layer)

Living elongated and irregularly thickened at the corners with very less intercellular space.

3. SCLERENCHYMA

Type of permanent tissue that makes the plant hard and stiffHusk of coconut is made of sclerenchymatous tissue.

Cells of this tissue are dead.

They are long, narrow as there walls are thickened due to lignin.

Present in stems, around vascular bundles, in the veins of leaves and in the hard covering of seeds and nuts.

Provides strength to the plant parts.

Difference betweenparenchyma ,collenchyma , sclerenchyma

EPIDERMAL CELLSFUNCTIONS

 Epidermal cells are cells on the outermost protective layer of a plant tissue.  

Epidermal cells on the aerial (in air) parts of the plant often secrete a waxy, water resistant layer on their outer surface. This aids in protection against loss of water, mechanical injury and invasion by parasitic fungi.

Cells of epidermal tissue form a continuous layer without intercellular spaces.

Most epidermal cells are relatively flat.

In some plants having dry habitats, the epidermis may be thicker since protection against water loss is critical.

Small pores on the epidermis of the leaf are called stomata.

Epidermal cells of the roots, whose function is water absorption, commonly have long hair like parts that greatly increase the total absorptive surface area.

In desert plants, epidermis has a thick waxy coating of cutin (chemical with waterproof quality).

stomata

Stomata are small pores in the epidermis of the leaf.Stomata are closed by two kidney shaped cells called guard cells.

The word stomata mean “mouth”.  These small pores found in the leaves of the plant helps in gaseous exchange during photosynthesis and respiration. Stomata consist of two types of cells, the stoma or the pore and guard cells. Stomata are guarded pair of crescent shaped specialized parenchyma cells called guard cells which regulates the size of opening or pore of stomata.

The main functions of stomata are:1. Exchange of atmospheric oxygen and carbon dioxide2. Transpiration. 

EPIDERMIS AS A PROTECTIVE TISSUE

As plants grow older, the outer protective tissue undergoes certain changes. A strip of secondary meristem replaces the epidermis of the stem. Cells on the outside are cut off from this layer. This forms the several-layer thick cork or the bark of the tree. Cells of Cork are dead and compactly arranged without intercellular spaces. They also have a chemical called suberin in their walls that makes them impervious to gases and water.

Complex permanent tissue1. xylem

Xylem consists of tracheids, vessels,xylem parenchyma and xylem fibres. The cells have thick walls, and many of them are dead cells. Tracheids and vessels are tubular structures. This allows them to transport water and minerals vertically.

The parenchyma stores food and helps in the sideways conduction of water.

Fibres are mainly supportive in function.

2. phloem

Phloem is a tubular structure conducting tissue in plants that is made up of four types of elements: sieve tubes, companion cells, phloem fibres and the phloem parenchyma.

Sieve tubes are tubular cells with perforated (having holes) walls.

In phloem, materials can move in both directions in it.

Phloem transports food from leaves to other parts of the plant.

DIFFERENCE BETWEEN XYLEM AND PHLOEM

ANIMAL TISSUES

ANIMAL TISSUE

Epithelial tissue

(Protection by covering,secretio

n,absorption)

Connective Tissue

(binding,support,transport)

Muscular tissue

(movement and locomotion)

Nervous Tissue

(control and co-ordiantion)

EPITHELIAL TISSUE

Structural Characteristics : The cells forming epithelial tissue –(i) are closely packed with no intercellular space in between.(ii) arise from a non-cellular basement membrane.(iii) not supplied with blood vessels.Function : line the surfaces, help in absorption, secrete, also bear protoplasmic projections such as the Cilia.

Types of epithelial tissue

1.

• SIMPLE SQUAMOUS• STRATIFIED SQUAMOUS

2.• CUBOIDAL

3.• CILIATED COLUMNAR

TYPE STRUCTURE LOCATION FUNCTION

Squamous Epithelium

Thin and flat cells.Form a delicate lining.

The oesophagus and the lining of the mouth .Lining of Kidney .

-For exchangeof O2 and CO2.-For absorption.tubules.-For exchange of materials.

Stratifiedsquamous

Cells are arranged in layers.

Skin -prevent wear and tear.

Cuboidal Epithelium

Cube like cells with acentrally placed nucleus. Cells appear polygonal.

Lining of salivary and pancreatic ductsFound in sweat, salivary gland.

-For absorption.-For secretion.

CiliatedColumnarEpithelium

Cilia at free ends.Tall column like cell with nucleus at the basal end ends .

Lining of trachea.Lining of stomach.Lining of kidney tubules.

-Flow of fluids in a particular direction-Secretion.-Absorption.

CONNECTIVE TISSUEThe cells of connective tissue are loosely spaced and embedded in an

intercellular matrix.The matrix may be jelly like, fluid, dense or rigid. The nature of matrix differs in concordance with the function of the particular connective tissue.

TYPE OF CONNECTIVE TISSUE

TYPE

PROPER

AEROLAR

ADIPOSE

FIBROUS

SUPPORTING

CARTILAGE BONE

FLIUID

BLOOD LYMPH

PROPER CONNECTIVE TISSUE

1. Areolar : Most widely spread connective tissue.The cells forming the tissue are :(i) Fibroblasts-which form the yellow (elastin) and white (collagen) fibers in the matrix.(ii) Macrophages-which help in engulfing bacteria and micro pathogens.(iii) Mast cell-which secrets heparin (helps in clotting of blood).

Areolar connective tissue is found between the skin and muscles, around blood vessels and nerves and in the bone marrow. It fills the space inside the organs, supports internal organs and helps in repair of tissues.

2.ADIPOSE TISSUE

Fat- storing adipose tissue is found below the skin and between internal organs. The cells of this tissue are filled with fat globules. Storage of fats also lets it act as an insulator.

3.FIBROUS-TENDONS,LIGAMENTS

Two bones can be connected to each other by another type of connective tissue called the ligament. This tissue is very elastic. It has considerable strength. Ligaments contain very little matrix. Tendons connect bones to muscles and are another type of connective tissue. Tendons are fibrous tissue with great strength but limited flexibility.

FLUID CONNECTIVE TISSUEBLOOD

Blood has a fluid (liquid) matrix called plasma, in which red blood cells (RBCs), white blood cells (WBCs) and platelets are suspended. The plasma contains proteins, salts and hormones. Blood flows and transports gases, digested food, hormones and waste materials to different parts of the body.

.

1. Red Blood Cells (Erythrocytes)-Transport O2 and CO2.2. White blood cells (Leucocytes)-Function in defense againstbacteria, viruses and other invaders.3. Platelets (Thrombocytes)-help in the clotting of blood.

SUPPORTING CONNECTIVE TISSUE

Cartilage, has widely spaced cells. The solid matrix is composed of proteins and sugars. Cartilage smoothens bone surfaces at joints and is also present in the nose, ear, trachea and larynx.

Bone is another example of a connective tissue. It forms the framework that supports the body. It also anchors the muscles and supports the main organs of the body. It is a strong and nonflexible tissue . Bone cells are embedded in a hard matrix that is composed of calcium and phosphorus compounds

Muscular tissue

1. Muscular tissue consists of elongated cells, also called muscle fibres.

2. This tissue is responsible for movement in our body.

3. Muscles contain special proteins called contractile proteins, which contract and relax to cause movement.

TYPES OF MUSCULAR TISSUE

• STRIATED1.

• SMOOTH2.

• CARDIAC3.

BASIS Striated/Voluntary/Skeletal

Unstriated/ Involuntary

Cardiac

LOCATION Attached to the skeleton likehead, limbs, face etc.

In the walls of body organslike stomach, intestines

Walls of heart.

SHAPE -Elongated, cylindrical,unbranched fibres

-there arestriations seen.

-Spindle shaped, tapering.

-No such striations seen

-Elongated, cylindrical,branched.

-Striations (stripes) seen.

NUCLEUS Multi nucleated, Peripheralnuclei.

Uninucleated, centrallyplaced.

One nucleus in each unit,centrally placed.

BLOOD SUPPLY Rich Poor Rich

CONTRACTS AT WILL

Voluntary Involuntary Involuntary

Nervous tissue

Cells of the nervous tissue are highly specialized for being stimulated and then transmitting the stimulus very rapidly from one place to another within the body.

The brain, spinal cord and nerves are all composed of the nervous tissue.

The cells of this tissue are called nerve cells or neurons.

A neuron consists of a cell body with a nucleus and cytoplasm, from which long thin hair-like parts arise. Usually each neuron has a single long part, called the axon, and many short, branched parts called dendrites.

TRANSMISSION OF NERVE IMPULSE

The branching dendrites receive the stimulus and transmit through the cyton to the axon, which finally transmits it through its variously branched end into either a muscle (to order it to contract) or to a gland (to order it to secrete). The axon constitutes the nerve fibre. The nerve fibre may or may not be covered by an extra sheath called medullary sheath secreted by sheath cells. It is made of myelin a lipid like substance. Accordingly, the nerve fibre is termed medullated and non-medullated. The medullary sheath is not continuous and is broken at nodes of Ranvier.

DIFFERENCE BETWEEN PLANT AND ANIMAL TISSUE

THE END

MADE BY :

AKHIL BANSAL