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TISSUE Class IX

TISSUE ; A group of cell that  are similar in structure and work together to achieve a particular function  called  Tissue , The microscopic  study of tissue is called  Histology .

PLANT TISSUE :  MERISTEMATIC  TISSUE / GROWTH TISSUE These are simple  living tissues having thin  walled compactly arranged immature cells which are capable of division and formation of new cells . The main feature of meristematic tissues are  It has thin primary cell wall (cellulose ) In compact tissue the intercellular space  are absent , generally  vacuoles are absent , dense cytoplasm and prominent nuclei present, Actively dividing cells are present  in the growing regions of plants such as root and shoots tips

CLASSIFICATON ON BASIS OF ORGIN

A)  Primary Meristem/Promeristem It is derived directly  from the meristem of the embryo. they consist of the cells derived from the primary meristem they add to primary growth of the plants.

B) Secondary Meristem ; These are having cells  derived from  primary permanent tissue and usually add to the diameter of plants .

CLASSIFICATION  ON THE BASIS OF LOCATION : A) APICAL MERISTEM  It is present  at the growth tips of stem and roots. Cell division  in this tissue  leads to the elongation of stem and roots thus it is involved in primary growth of the plant B) INTERCALARY MERISTEM  It is present behind the apex , helps in longitudinal growth .It is the part of meristem which is left behind during the growth of the period these are present at the base of the leaf and internode region these lead to increase in the length of leaf eg grass stem, bamboo stem , mint stem C) LATERAL MERISTEM/CAMBIUM ; It is also called as  secondary meristem it occurs along the side of longitudinal axis of the plant, It gives rise to the vascular  tissues and responsible for the growth in girth of stem and root They are responsible for the secondary growth by increasing the grith

PERMANENT TISSUE ;The permanent tissue are formed  from those meristematic  cells which are left behind and have lost their capability to divide , the division and differentiation  of the cells of meristematic tissue give rise to permanent tissues they have definite shape ,size , thickness they may be dead or living as a result of cell  differentiation the meristematic tissues tend to form different type of permanent tissues . In cell differentiation , developing tissues changes from  simple to more complex forms to perform various  specialized functions. Depending  upon structure  and composition the permanent tissues are classified into two types A) SIMPLE PERMANENT TISSUE  ( It is  Supporting and protective  tissue )

PROTECTIVE TISSUE; These Dermal  tissues are  primarily  protective  in function they cosist of  a) EPIDERMIS  It  forms one cell  thick outermost  layer of various body organs  of plants such as leaves, flowers, stem and roots Epidermis is covered outside  by cuticle . Cuticle  is a water proof layer  of waxy substance  called cutin  which is secreted by the  epidermal cells and provide protection  against the loss of water and also invasion  by microbes cells of epidermis of leaves are not continuous  at some places due to presence of small pores called  stomata each stomata is guarded by a pair of bean shaped cells called guard cells these are only epidermal cells which possess chloroplasts the rest being colourless

FUNCTION The main function is to protects the plant from desiccation and infection  the cuticle of the epidermis  cuts the rate of  transpiration and evaporation of water and prevent wilting of leaves stomata also allows the gaseous exchange to occur  during photosynthesis and respiration also helps in transpiration

PHELLEM/ CORK  : In older roots and stems , tissues at the periphery  become cork cells. They are made of dead cells with thick walls without any intercellular  space  The cell wall in the cork deposit waxy substance suberin and it is impermeable to water and gases due to deposition of suberin  The cork cells are without any protoplasm  but are filled with resin or tannins .

FUNCTIONS : It is protective in function the cork cells prevent  p lants from desiccation , infection and mechanical injury  It is perviousness , lightness , toughness ,  compressibility and elasticity so make the cork valuable for commercial use

SUPPORTING TISSUES  These Are  supportive  in function and are of three types ; Basic type of plant tissues are Parenchyma ,, collenchyma , sclerenchyma  tissue

Parenchyma It is the fundamental backing tissues they are loosely packed thin walled cells, oval / spherical in shape with the large space between them , they  are composed  of cellulose and pectin having large central vacuole for food and water storage  and primary  function  is food storage and packing  It’s main kind a)Idioblast  some  parenchyma  involved  in storage  of excretory substances such as resin tannin gum and oil in typical parenchyma  chlorophyll is absent b) Chlorenchyma  It contain chloroplast to perform photosynthesis ( mesophyll  cells of leaves ) c)Aerenchyma are found in hydrophytic plants due to having space between them for which they have buoyancy for floating

COLLENCHYMA which is the living mechanical tissue their elongated cell with thick corners, localized cellulose and pectin thickening It provides flexibility and easy bending of various parts of plants few chloroplast may be present .It give mechanical strength and elasticity to growing stems and have very little intercellular space There are fibres in L.S  Which are composed of extremely thick walled cells with little or no  protoplasm they are dead and possess very thick lignified walls Lignin is water proof material and intercellular spaces absent.

SELERENCHYMA : They are of two types  a) Selereids  these are also called grit cells / stone cells . These are small cells  where lumen  is so small due to  higher thickening of cell wall , as present in drupe fruit Fiber  such as mango / coconut/ walnuts . b) FIBRES are long ,narrow , thick lignified cells . Lumen  is a large as compared to selereids . Generally 1-3 mm long . In the thick walls of both  the fiber and  selereids thin aeras called as pits are present Uses : These are used in the manufacture of ropes, mats and certain textile fibres and jute and coir are obtained from thick bundle of fibres .

DIFFERENCE BETWEEN PARENCHYMA ,COLLENCHYMA AND  SCLERENCHYMA

A) Parenchyma ;  It has primary cell walls The cell shape is isodiametric cell which are  oval , spherical and polygonal in shape , Thin cellulosic cell wall , cytoplasm is abundant , Nucleus is present with large vacuole ,intercellular space is present  they are basically packing tissue ,all soft part plant pith , cortex and medullary rays the main function is food storage, photosynthesis , provide buoyancy to hydrophytes

B) COLLENCHYMA : Primary cell wall are irregularly thickness, They are circular, oval or polyhedral in shape  , cytoplasm is present , vacuolated , intercellular space absent , they are found in dicots stems, petiole and beneath the epidermis  and absent in monocot and roots  it provides tensile strength , mechanical support , photosynthesis

C) Sclerenchyma : It is variable in shape . fibres and selereids , having lignified secondary cell wall present , cytoplasm is absent having dead tissue, no  vacuoles , no intercellular space present in Dicot hypodermis, bundle sheath ,pericycle , seed, pulp of fruits  this protect the stress and strain  mechanical strength.

COMPLEX PERMANENT TISSUES ; It consist  of more than  one type of cells which work together as a unit It helps  in the transportation of organic materials, water and minerals It is also known  as conducting  or Vascular  tissue Xylem and Phloem together form  vascular  bundles .

XYLEM  It is  also known as wood and is  a vascular and mechanical tissue. It help in transportation of water and minerals from the soil to the plants parts. Xylem is consists  of a) Tracheid   which are elongated dead cells /primitive elements mainly involved in the conduction of water and minerals in gymnosperms  b) Vessels they are advance  element ( generally found  in  angiosperm )  Vessels are cylindrical tubelike structure place done above the other end to end which form the  continuous channel for efficient conduction  of water  c)Xylem Parenchyma : They are small and thick walled parenchymatous  cells designed for the stroge of starch /food  d) Xylem Sclerenchyma They are  non living fibers with  thick walls and narrow cavities which provides mechanical support Except xylem Parenchyma all other xylem elements are dead the annual rings  present in the  trunk of a tree are xylem rings by contented number of annual rings we can determine the age of the plants

PHLOEM : It transport /translocation food from  leaves  to other parts of the plant.  All the phloem cells are living except phloem fibre It consist of four parts  a) Sieve tubes  are the tabular structures’ made up of elongated, thin walled cells placed end to end . The end walls of sieve  tube cells are perforated by  numerous the pores called  sieve  plates , The Nucleus of sieve  cell  degenerates  at the maturity. However cytoplasm persists because of protoplasm  continuation of sieve tube with the companion cell through plasmodesmata b) Companion cells  have dense cytoplasm and prominent  nuclei the sieve tubes and companion cells are also  called sister cells because they originate from single mother cells  c) Phloem fibre/ Phloem Sclerenchyma  give mechanical support to sieve tubes and dead d)Phloem parenchyma  store food and help  in radial conduction of food  ,

Difference between Xylem and Phloem : Xylem are dead cells,  thick , having lignin , impermeable , carries water and minerals upward flow  direction . Phloem are  living cells  ,they are thin , permeable , having sieve plates  it carries sugar and flow is upward and down ward

EPITHELIAL TISSUE  ; The cells of epithelium are set very close to each other tightly packed and the tissue rests on  a non cellular basement  membrane and consists of single layers of cells It covers all the organs  and the line cavities of hollow organs  like stomach It is primarily protective in function.  There are  different types A) SQUAMOUS  EPITHELIUM :  It is also called pavement epithelium ,, cells are arranged end to end likes  tiles on the floor, cells are polygonal  in surface view  It forms the delicate lining of cavities ( mouth, oesophagus, nose ,  pericardium, alveoli )blood vessels and  covering of the tongue and skin. Epithelial cells are arranged  in many layers to prevent wear and tear in skin . This pattern is stratified squamous  epithelium. B) CUBOIDAL EPITHELIUM : They are cube like  cells that fit closely , cells look like  squares in the section but free surface  appears hexagonal. It is found in kidney tubules, thyroid vesicles and in the glands ( Salivary  glands  Sweat glands ) It form germinal epithelium of gonads  (testes and ovaries ) It is involved in absorption, excretion  and secretion It also provides mechanical support  C) CILIATED EPITHELIUM : These cells may be  cuboidal / columnar found in the respiratory  tract , lining of the super duct, oviduct and kidney  tubules on its free surface are  present protoplasmic outgrowth called cilia It helps in the movement of ova  in fallopian tubes  D) GLANDULAR EPITHELIUM :  Gland  cells secretes substances at the epithelial  surface. Sometimes  position  of epithelial  tissue folds inward and form  multicellular gland  so it is called  GLANDULAR EPITHELIAL

CONNECTIVE TISSUES  The cells of these tissue  are widely spaced  and embedded in an intercellular matrix their basic function is to provide support  to different organs and keeping  them in place  connective tissues have two components as matrix and cellular part.

A) FLUID or VASCULAR TISSUE ;  Blood and Lymph  : Blood is a connective tissue, fluid matrix of blood is plasma  having  wandering/ floating cells called corpuscles, blood  helps  in the  transportation of various materials such as  nutritive substances , gases, excretory products and hormones etc.  i) Plasma it form 55% part of blood, constitution  90-92% Water 7% Protein 0.9%  ( Albumin , fibrinogen , globulin )  and inorganic salts ii) Corpuscles  forms 45%   part of blood  iii) RBC (Red Blood Corpuscles )  they are also called erythrocytes,  containing red color respiratory pigment called hemoglobin that helps  in transportation of oxygen  iii) WBC ( White Blood Corpuscles ) /Leucocytes they  ae also called as  soldiers of our body, it provide immunity . They are irregular amoeboid ,phagocytes cells  that protect our body by engulfing bacteria and other foreign particles they are of five types  monocytes, Lymphocytes , Basophils , Neutrophils Eosinophils  iv) Blood platelets / thrombocytes : They are spindle shaped cells  which are involved  in clotting of blood .

SKELETAL TISSUE  : a) BONE  It is hard connective tissue that form supportive  framework ie skeleton of our body . It is of two type i) Bone  the matrix of bone is very hard because of  salts  such as calcium , phosphate , CaCO3 (60-70%) and protein  ossein .Bone cells / osteoblast are embedded in the hard matrix which is deposited  in the form of connective layers of lamellae  formed around a central canal , the bone cells occupy small spaces the concentric layers of matrix  b) CARTILAGE  These tissue are elastic, less harder as compared to bones, Elasticity is due to  the presence of  chondrin/protein. Cells are called as chondrocytes  which are widely  spaced and matrix  is reinforced by fibres Itis found at joint of bones of  bones , in those , ear , trachea and larynx it provides the flexibility and great tensile strength.

FIBROUS TISSUE : It is of two type i) Ligament ii)Tendon  It is the most abundant type of connective tissue It is further divided  into following types yellow fibrous connective tissue/ ligament they are very elastic due to the presence of  a network of yellow fibres in the matrix called ligaments which are attached to the bone to bone where as white fibrous connective tissue / tendon  which have very little matrix  containing abundant  white fires  forming layers and non elastic in nature  bundles of these tissue are called tendons which attach muscles to bones . The tissue fill the space inside the organ and found between the skin and muscles around the blood vessels , nerves and in bone marrow .It is a supporting and packing tissue . It also helps in repair the tissue after injury

ADIPOSE TISSUE  These are oval and round cells , filled with fat globules called adipocytes It is found in  subcutaneous layer below the skin, around the heart, brain, below eye balls . It acts as  insulator and prevent loss of heat from the body .It severs as a fat  reservoir and keeps the visceral organs in position.

MUSCULE TISSUE : Movements are brought about in our body with the help of muscular tissue . They are long fibre like cells called muscle fibes . They  are capable of contraction/ relaxation because they are up of contractile proteins. a) Skeletal  Muscles : These muscles shows alternate  light and dark bands hence the name is striped or striated muscles. They are also called as voluntary  muscles because these are under the control of one’s will. Muscle fibers/ cells  are  multinucleated  and unbranched each fibre  is enclosed  by thin membrane which is called as sarcolemma It’s Cytoplasm  is called as  sarcoplasm. these muscles get tired and need rest   b) Cardiac Muscle : They are involuntary muscles only found  in the walls of heart and they are unnucleated and branched.  The branches are united by intercalated  disc. In  these muscles rhythmic  contraction and  relaxation occurs throughout the life and never get tired . c)  Non Striated  Muscles : They are involuntary muscles also called as smooth muscles, these muscles fibres  are unnucleated and spindle shaped. They are not enclosed by membrane but many  fibres are joined together in the bundles. They  constitute  internal organs. Such muscles  are found  in the walls of stomach, intestine, urinary bladder , bronchi ,iris of eye. Peristaltic movement in the alimentary canal . are brought about by  smooth muscles.

STRIATED MUSCLES :  They are present in limbs, body walls , tongue pharynx and the beginning of oesophagus. They are cylindrical  with  fibres unbranched, multinucleated. They are bounded by  sarocolemma  having light and  dark bands , there is no oblique bridges and intercoalated discs , nerve supply from centrak nervos system and blood supply to it is abundant  , have rapid contraction they soon get fatigue used in voluntary action .

NON STRIATED MUSCLES : they are found in  posterior part of  oesophagus , urino genital tract,  urinary bladder , iris of  eye , dermis of skin etc They are spindle in shape with unbranched fibres, unnucleated ,  bounded with plasmalemma,  they do not have bandstand no oblique bridges and intercalated discs. Nerve supply to it is from autonomic nervous system  having slow contraction , involuntary so do not get fatigue

CARDIC MUSCLES  : They are present in the walls of heart , pulmonary veins and superior vena cava . They are cylindrical in shape , having fibrous branch ,  uni- nucleate  bounded by  sarcolemma , having faint light and dark bands oblique bridges and intercalated discs present  Nerve supply from the brain and autonomic  nervous system , blood supply to it is abundant having  rapid contraction , never get fatigued and involuntary in nature .

NERVOUS TISSUE  :  They are highly specialized  tissues due to which the animals are able to perceive and respond to the stimuli . Their functional unit is called  nerve cell/ neuron. The main part cell body  is cyton  covered with plasma membrane., short hair like extension rising from cyton  are  dendrons which are further which are further subdivide into dendrites . Axon is long, tail like cylindrical  structure with fine branch at the end and is covered  by sheath , which is known as  myelin sheath. Nerve ending  of  one  neuron  is very closely placed to dendron’s of  the other neuron to carry  impulses from  one neuron to another in the form of electro- chemical waves. This closes the  proximity is called synapse

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