Please enable JavaScript.

Coggle requires JavaScript to display documents.

Tissues: A tissues is a group of similar cells performing a specific…

- - - - Location
    - - location
        
        near the tips of roots and stems
        
        in the growing young leaves near the tips of stems
        
        on the tips of axillary buds
    - - location
        
        situated below the bark and is responsible for the increase in the girth of the stem.
  - - - location-
        
        cells with thick walls.
        
        found on the surface of roots, stems and leaves.
        
        example-
        1) epidermis of leaves which secrets a waxy water-proof material.
        2) Cork cells in the barks contain another strong water-proof material.
    - - it provides a passage for water and dissolved materials to move up and down in the plant
      - Phloem
        
        they provide a passage for the downward movement of food manufactured in the leaves go various parts of the plant.
        
        they also provide for the upward movement of the prepared food towards the growing new leaves
        
        Phloem tissues consists of
        
        companion cells
        
        companion cells r living parenchyma cells closely associated with sieve tube cells.
        
        they help in the functioning of the sieve tube cells.
        
        phloem parenchyma cells
        
        it is a parenchymatous tissue found associated with phloem.
        
        mainly concerned with storage of starch, fat and other organic food material.
        
        sieve tubes
        
        they r made up of elongated cells placed end to end forming a long tube.
        
        the transverse walls called sieve plates are perforated.
        
        they help in the transport of food from leaves to storage organs and other parts of the plant.
        
        phloem fibres
        
        They r sclerenchymatous cells found associated with phloem.
        
        they mainly provide support.
      - Xylem
        
        xylem cells are elongated and thick-walled.
        
        These cells r somewhat in the form of tubular passages.
        
        they provide upward movement of water and dissolved materials absorbed from the soil by the roots to other parts of the plant.
        
        older xylem tissue forms the wood and does not participate in transport.
        
        u can determine the age of a tree by counting its annual rings which actually r the xylem rings.
        
        The xylem tissue consists of :-
        
        xylem vessels/ trachea
        
        they r long tube-like structures meant for transporting water, and dissolved minerals.
        
        They r made up of elongated cells placed end to end.
        
        their cell walls r quite hard, hard and lignified.
        
        1 more item...
        
        xylem parenchyma
        
        it consists of living parenchyma cells associated with the xylem.
        
        these cells serve for the storage of food ( sugar& starch), and also help in the conduction of water and minerals.
        
        tracheids
        
        They r made up of elongated dead cells with large cavities without any contents.
        
        These cells are placed end to end forming a long tube.
        
        they have highly lignified cell walls.
        
        1 more item...
        
        xylem fibres
        
        they r made up of dead sclerenchyma cells.
        
        they r thick-walled, long, narrow cells with tapering ends.
        
        their main function is to provide mechanical support tp the plant.
      - vascular bundles
        
        the xylem and phloem are collectively form the vascular bundles
        
        eg- the veins of leaves.
        
        they r in continuity with the conducting tissues of stem and root.
        
        xylem and phloem r called complex tissues as they r made of more than one type of cells working together as a unit.
    - - Collenchyma
        
        made up of cells which are elongated and the cell wall is elongated and the cell wall is thickened at the corners.
        
        found in the leaf stalks and below the epidermis of stems.
        
        it helps to support the parts of a plant.
      - Sclerenchyma
        
        composed of long, narrow cells, which have become dead.
        
        these cells develop very thick walls due to deposition of lignin.
        
        it provides strength to plant parts
        
        found in stems and veins of the leaves.
      - Parenchyma
        
        Large thin-walled cells, oval, circular or polygonal in shape.
        
        usually a single large vacuole is present.
        
        found in soft parts of plants, such as in the cortex (other region) and in the pith (central region)
        
        may store food as in potatoes.
        
        provide temporary support tot he plant
        
        chlorenchyma- they r the parenchyma cells that r found in leaf containing chloroplasts
        
        it helps the leaf to produce food by photosynthesis.
- - - - Abundance of intercellular substance- the matrix.
        
        fewer cellular elements.
        
        fibres.
    - - (a) Cartilage
        
        it is a non-porous tissue.
        
        it has thickened intercellular substance (matrix).
        
        it has blood vessels or nerves.
        
        it is semi-transparent and elastic
        
        found in the tip of the nose, external ears, trachea and bronchial tubes, between vertebrae, and at the ends of long bones.
      - (b) Bone
        
        it is a hard porous tissue.
        
        it has a good supply of blood vessels and nerves.
        
        it consists of both living cells (called osteoblasts) and a rigid mass of inorganic salts.
    - - (a) Blood
        
        it is composed of:-
        i) The liquid part- plasma
        ii) the cellular part-- RBCs, WBCs and platelets.
      - (b) lymph
        
        it is the fluid surrounding the body cells.
        
        it is essentially the blood plasma that has oozed out of the blood vessels
        
        it contains WBCs and not the RBCs
    - - Adipose (fat) tissue.
        
        It has specialized cells which store fat.
        
        this tissue forms padding under the skin and around kidneys, eye balls, etc.
        
        padding under skin acts as an insulation for retaining body heat.
      - (a) Areolar (packing) tissue
        
        it is most wildly spread, occurring beneath the epidermis of skin.
        
        it makes the skin elastic and helps it to withstand pulling strain.
      - (c) Fibrous connective tissue
        
        it is made up of elongated cells referred to as 'fibres'.
        
        the fibres are strong and bundled together by areolar tissue.
        
        they form the tendons which connect muscle to bones, and ligaments which connect bone to bone and hold them in position.
  - - - these muscles r not under our will.
        
        they r made up of spindle- shaped/slender tapering cells which r uninucleated.
        
        found in the walls of the intestine helping in the passage of food, muscles of the iris of the eye, skin lining of blood vessels, etc.
    - - muscles can contract and relax.
        
        they the body in its movements.
    - - these muscles r involuntary in function and found in the walls of the heart.
        
        the fibres of cardiac muscles r straited, uninucleated and branched.
        
        they r relatively short.
        
        they can contract without stimulation and do not get tired soon.
    - - these muscles r under our will.
        
        they r made of long fibres which are nucleated and straited-- light and dark bands run across the fibres.
        
        this muscle only moves when u want it to.
        
        they constituent about 50% of the body weight.
        
        found in the arms, legs, face, neck, etc.
  - - - it covers the surface of the body and lines the various body cavities and internal organs, including the blood vessels.
        
        eg
        1) the outermost layer of skin
        2) the lining surface of the mouth, nose, stomach, etc.
    - - epithelial cells may be flat, cuboidal or columnar in shape.
        
        In all cases, the epithelial tissue fit tightly together leaving no space between them.
    - - it functions for protection, absorption and secretion , sensory perception, etc