Tissue: Plant and Animal

• Tissue


  A tissue is a group of similar cells performing a specific function.
• Organ


  Several tissues together

  contributing to some specific function inside the

  body, constitute an organ
• Organ system


  Many organs acting together to perform a a specific life

  process constitute an organ system
• Organism


  Organ systems together constitute

  the organism
• Meristematic tissues are found at


  Found at all growing points of a plant, such as the tips of roots, stems and branches

  Also present between the bark and the wood → of trees where it leads to growth in the diameter of the stem.
• Meristematic tissues


  Meristematic tissue cells can multiply to produce new cells
• Meristematic cells


  (1) Cells are small.

  (2) Cells are usually cubical.

  (3) Cell wall is thin.

  (4) Nuclei are large.
• Apical meristem


  Apical or Terminal meristem. This is located near the tips of roots and stems and also in the growing young leaves near the tips of stems, as well as on the tips of axillary buds.
• Lateral meristem


  Lateral or Cambium meristem. This is situated below the bark and is responsible for increase in the girth (diameter) of the stem.
• Protective cells


  cells with thick walls.

  found on the surface of roots, stems and leaves.

  Examples: Epidermis of leaves which secretes a waxy water-proof material. Cork cells in the barks contain another strong water-proof material..
• 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 (outer region) and in the pith (central region)
• Collenchyma


  Made up of cells which are elongated and the cell wall is thickened at the corners.. It is found in the leaf stalks and below the epidermis of stems) The tissue helps to support the parts of a plant.
• Schelerenchyma


  Composed of long, narrow cells, which have become dead; these cells develop very thick walls due to the deposition of lignin. This tissue provides strength to plant parts. It is found in stems and veins of the leaves
• Xylem


  Xylem cells are elongated and thick-walled. These cells are somewhat in the form of tubular passages. They provide for upward movement of water and dissolved materials absorbed from the soil by the roots to other parts of the plant.
• Xylem tracheids


  Tracheids are made up of elongated dead cells with large cavities without any contents. The cells are placed end to end forming a long tube. They have highly lignified cell walls. They provide mechanical support by developing various types of thickenings in their walls.
• Xylem vessels


  Xylem Vessels or tracheae are long tube-like structures meant for transporting water, and dissolved minerals. They are made up of elongated cells placed end to end. Their cell walls are quite hard, thick and lignified. Transverse walls get dissolved and make a continuous water pipe transverse walls
• Xylem parenchyma


  Xylem parenchyma consists of living parenchyma cells associated with the xylem. These cells serve for the storage of food (sugars and starch) and also help in the conduction of water and minerals.
• xylem fibers


  Xylem fibres are made up of dead sclerenchyma cells. They are thick-walled, long, narrow cells with tapering ends. Their main function is to provide mechanical support to the plant.
• Phloem


  provide a passage for the downward movement of food manufactured in the leaves to various parts of the plant. They also provide for the upward movement of the prepared food towards the growing new leaves.
• Sieve tubes


  Sieve Tubes are 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.
• Companion cells


  Companion cells living parenchyma cells closely associated with sieve tube cells. They help in the functioning of the sieve tube cells.
• Phloem parenchyma


  Phloem parenchyma is a parenchymatous tissue found associated with phloem. Mainly concerned with storage of starch, fat and other organic food material.
• phloem fibers


  Phloem Fibres are sclerenchymatous cells found associated with phloem. They mainly provide support.
• Companion cells


  is composed of cells, which are thin, flat with prominent nuclei closely packed Examples: Found lining the mouth and nasal cavities, blood vessels and lymph vessels.

  The squamous epithelium protects the underlying parts from mechanical injury, germs, harmful chemicals, and drying up.
• cuboidal epithelium


  cuboidal epithelium is found in some parts of kidney tubules and in some glandular ducts such as those of salivary glands, pancreatic duct
• ciliated epithelium


  At some places in the body, such as in the lining of the trachea (wind pipe), the columnar epithelium is ciliated. The cells of ciliated epithelium have thread-like protoplasmic projections called cilia, at their free ends. The cilia constantly keep lashing and move the materials which enter these regions.
• glandular epithelium


  contains some large cells which secrete certain chemical substances. Such cells are common in the lining of the stomach and the intestine. At certain places in the body, the glandular epithelium is folded inward to form compact, hollow or tubular glands; for example, the sweat glands, tear glands or the liver.
• stratified epithelium


  Found in the skin and the cornea. It is composed of several layers (strata) of the same or different kinds of epithelial cells.
• Areolar tissue


  It is most widely spread, occurring beneath the epidermis of skin. It makes the skin elastic and helps it to withstand pulling strain.
• Adipose tissue


  It has specialized cells which store fat. This tissue forms padding under the skin and around kidneys, eye ball, etc.
• Tendons


  Connect muscle to bone
• Liagaments


  connects bones to bones
• Cartilage


  Cartilage is a non-porous tissue. It has a thickened intercellular substance (matrix). It has no blood vessels or nerves. Cartilage is semi-transparent and elastic. Cartilages are found in the tip of the nose, external ears, trachea and bronchial tubes, between vertebrae, and at the ends of long bones.
• Bone


  Bone 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.
• Blood


  The liquid part - plasma and

  (ii) The cellular part - red blood cells, white blood cells and platelets
• White Blood cells


  Lymph is the fluid surrounding the body cells. It is essentially the blood plasma that has oozed out of the blood vessels. It contains white blood cells and not the red blood cells
• Striated muscles


  Striated muscles are under the control of our will. They are made of long fibres (cells) which are nucleated and striated - light and dark bands run across the fibres.(Fig 3.12A). This muscle moves only when you want it to . They constitute about 50% of the body weight. These muscles are found in the arms, legs, face, neck, etc.
• Unstriated muscles


  Unstriated muscles are not under the control of our will. They are made up of spindle-shaped/slender tapering cells which are unucleated. They are 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, urinary bladder, uterus, etc.
• Cardiac muscles


  Cardiac muscles are involuntary in function and found only in the walls of the heart. The fibres - of cardiac muscle are striated, uninucleated and branched. They are relatively short. They can contract without outside stimulation and do not get tired soon.