TISSUES

Multi-cellular organisms mein, cells group hokar tissues banate hain, jo specific functions perform karte hain. Plants aur Animals ke tissues mein kaafi differences hote hain, unke lifestyle aur needs ke according.

• Plants:
• Stationary (fixed): Ek jagah par rehte hain, move nahi karte.
• Supportive tissue: Zyada hota hai, usually dead cells se bana hota hai (e.g., wood), taaki plant ko upright support mile.
• Energy consumption: Kam hota hai.
• Growth: Limited regions mein hoti hai (meristematic regions), throughout life divide karte hain.
• Structural organization: Simple hoti hai, organ systems less specialized hote hain.

• Animals:
• Motile (move karte hain): Food, shelter, mates ki search mein move karte hain.
• Living tissue: Zyada hota hai, energy consumption high hoti hai.
• Growth: Zyada uniform hoti hai, dividing aur non-dividing regions ka clear demarcation nahi hota.
• Structural organization: Complex aur highly specialized organ systems hote hain.

Key takeaway: Ye differences unke alag-alag modes of life (plants ka sedentary, animals ka active locomotion) aur feeding methods ko reflect karte hain.

Plants mein growth sirf kuch specific regions mein hoti hai. Ye regions meristematic tissue ke presence ke karan hote hain, jisme cells continuously divide karte hain.

• Characteristics of Meristematic Cells:
• Highly active: Bahut active hote hain.
• Dense cytoplasm: Cytoplasm ghana hota hai.
• Thin cellulose walls: Cell walls patli hoti hain.
• Prominent nuclei: Nuclei bade aur clearly visible hote hain.
• Lack vacuoles: Vacuoles nahi hote ya bahut chhote hote hain. (Kyunki ye cells rapid division aur growth mein involved hote hain, storage ki zaroorat kam hoti hai).

• Types of Meristematic Tissue (Location ke basis par):

1. Apical Meristem:

• Location: Roots aur stems ke growing tips par present hota hai.
• Function: Plant ki length increase karta hai (primary growth).

1. Lateral Meristem (Cambium):

• Location: Stem aur root ke sides mein present hota hai.
• Function: Plant ki girth ya thickness increase karta hai (secondary growth).

1. Intercalary Meristem:

• Location: Kuch plants mein nodes ke paas, leaves ke base par ya internodes mein paya jaata hai.
• Function: Internodes ki length increase karta hai, branches aur leaves ki growth mein help karta hai (e.g., grasses mein).

Differentiation: Meristematic cells jo naye bante hain, initially meristem jaise hi hote hain. Lekin jaise-jaise wo grow aur mature hote hain, unki characteristics change hoti hain aur wo differentiated hokar permanent tissues ke components ban jaate hain. Is process ko differentiation kehte hain, jisme cells ek permanent shape, size aur function acquire kar lete hain aur divide karne ki ability kho dete hain.

Permanent tissues, meristematic tissues se bante hain jab cells differentiate ho jaate hain aur divide karne ki ability kho dete hain. Ye tissues plant ko support, protection aur transport provide karte hain.

Types of Permanent Tissues:

1. Simple Permanent Tissue: Sirf ek type ke cells se bane hote hain.
2. Complex Permanent Tissue: Ek se zyada type ke cells se bane hote hain, jo collectively ek common function perform karte hain.

3.1 Simple Permanent Tissue

Ye tissues ek hi type ke cells se bane hote hain jo structure aur function mein similar hote hain.

• Parenchyma:
• Characteristics: Most common, unspecialized cells, thin cell walls, living cells, loosely arranged, large intercellular spaces.
• Location: Plant ke soft parts (cortex, pith, mesophyll) mein.
• Functions:
• Food storage (starch, proteins, oils).
• Chlorenchyma: Agar chlorophyll ho, toh photosynthesis karta hai.
• Aerenchyma: Aquatic plants mein large air cavities, buoyancy provide karta hai (float karne mein help karta hai).
• Packing tissue: Dusre tissues ko fill karta hai.

• Collenchyma:
• Characteristics: Living cells, elongated, irregularly thickened at corners (pectin deposition), very little intercellular space.
• Location: Leaf stalks (petioles) ke neeche, young stems ke epidermis ke neeche.
• Functions: Plant ko flexibility provide karta hai (bending without breaking), mechanical support deta hai.

• Sclerenchyma:
• Characteristics: Dead cells, long aur narrow, cell walls lignin ke deposition se thick hoti hain, no internal space (lumen) inside cell.
• Location: Stems mein, vascular bundles ke around, leaves ki veins mein, seeds aur nuts ki hard covering mein (e.g., coconut husk).
• Functions: Plant parts ko hard aur stiff banata hai, mechanical strength aur support provide karta hai.

• Protective Tissues (Epidermis aur Cork):
• Epidermis:
• Characteristics: Plant ki outermost layer, usually single layer of cells, no intercellular spaces, flat cells.
• Functions: Protection against water loss, mechanical injury, aur parasitic fungi.
• Stomata: Epidermis mein chhote pores, guard cells se enclosed. Gas exchange aur transpiration mein help karte hain.
• Cutin: Desert plants mein epidermis par thick waxy coating (cutin) hoti hai, water loss reduce karne ke liye.
• Root epidermal cells: Long hair-like parts hote hain, absorptive surface area badhane ke liye.
• Cork (Phellem):
• Characteristics: Older plants mein banta hai, dead cells, compactly arranged, no intercellular spaces, walls mein suberin hota hai (impervious to gases aur water).
• Functions: Protective layer, water loss aur infection se bachata hai.

3.2 Complex Permanent Tissue

Ye tissues ek se zyada type ke cells se bane hote hain, jo ek common function ke liye coordinate karte hain. Inhe vascular tissues bhi kehte hain, aur ye vascular bundles banate hain.

• Xylem (Jal-vaahak):
• Function: Water aur minerals ko roots se plant ke dusre parts tak transport karta hai.
• Components:

1. Tracheids: Long, tapering cells, thick walls, dead at maturity. Water conduction.
2. Vessels: Tube-like structures, thick walls, dead at maturity. Water conduction.
3. Xylem Parenchyma: Living cells, food storage.
4. Xylem Fibres: Dead cells, supportive function.

• Note: Xylem ke zyadaतर components dead hote hain.

• Phloem (Bhojan-vaahak):
• Function: Food (sugars) ko leaves se plant ke dusre parts tak transport karta hai.
• Components:

1. Sieve Tubes: Tubular cells, perforated walls (sieve plates), living but lack nucleus.
2. Companion Cells: Living, sieve tube cells ke functions ko control karte hain.
3. Phloem Parenchyma: Living, food storage.
4. Phloem Fibres: Dead cells, supportive function.
5. Sieve Cells: Primitive plants mein hote hain.

• Note: Phloem fibres ko chhodkar, phloem ke sabhi components living hote hain.

Animal body mein epithelial tissue covering ya protective tissue hota hai. Ye organs aur cavities ko cover karta hai aur body systems ko separate rakhta hai.

• Characteristics:
• Tightly packed cells: Cells ek doosre se tightly packed hote hain.
• Continuous sheet: Ek continuous layer banate hain.
• Little cementing material: Cells ke beech bahut kam cementing material hota hai.
• Almost no intercellular spaces: Intercellular spaces na ke barabar hote hain.
• Basement membrane: Underlying tissue se ek extracellular fibrous basement membrane se separated hote hain.
• Permeability: Materials ke exchange ko regulate karta hai.

• Types of Epithelial Tissue (Shape aur Function ke basis par):

1. Simple Squamous Epithelium:

• Characteristics: Extremely thin, flat, delicate lining (squama = scale of skin).
• Location: Blood vessels ki lining, lung alveoli, oesophagus, mouth ki lining.
• Function: Diffusion aur filtration (selective permeability).

1. Stratified Squamous Epithelium:

• Characteristics: Squamous cells ki kai layers, wear and tear se bachane ke liye.
• Location: Skin.
• Function: Protection against abrasion.

1. Cuboidal Epithelium:

• Characteristics: Cube-shaped cells.
• Location: Kidney tubules ki lining, salivary glands ke ducts.
• Function: Mechanical support, secretion aur absorption.

1. Columnar Epithelium:

• Characteristics: Pillar-like (tall) cells.
• Location: Inner lining of intestine, respiratory tract.
• Function: Absorption aur secretion, movement across epithelial barrier.

1. Ciliated Columnar Epithelium:

• Characteristics: Columnar cells par cilia (hair-like projections) hote hain.
• Location: Respiratory tract.
• Function: Cilia ki movement mucus ko forward push karti hai, passage ko clear karti hai.

1. Glandular Epithelium:

• Characteristics: Epithelial cells jo additional specialization acquire karte hain as gland cells.
• Formation: Kabhi-kabhi epithelial tissue andar ki taraf fold hokar multicellular gland banata hai.
• Function: Secretion of substances (e.g., sweat, enzymes).

Connective tissue body ke dusre tissues aur organs ko connect aur support karta hai. Iski cells loosely spaced hote hain aur ek intercellular matrix mein embedded hote hain.

• Characteristics:
• Loosely spaced cells: Cells ek doosre se door-door hote hain.
• Intercellular matrix: Cells ek non-living matrix mein embedded hote hain. Matrix jelly-like, fluid, dense ya rigid ho sakti hai. Matrix ki nature tissue ke function par depend karti hai.

• Types of Connective Tissue:

1. Blood:

• Matrix: Fluid matrix jise plasma kehte hain.
• Components: Plasma mein RBCs (Red Blood Corpuscles), WBCs (White Blood Corpuscles), platelets, proteins, salts aur hormones suspended hote hain.
• Function: Transport of gases (O2, CO2), digested food, hormones, aur waste materials throughout the body.

1. Bone:

• Matrix: Hard matrix jo calcium aur phosphorus compounds se bani hoti hai.
• Characteristics: Strong aur non-flexible tissue.
• Function: Body ko framework aur support provide karta hai, muscles ko anchor karta hai, main organs ko protect karta hai.

1. Ligament:

• Characteristics: Very elastic, considerable strength, very little matrix.
• Function: Do bones ko connect karta hai (Bone to Bone).

1. Tendon:

• Characteristics: Fibrous tissue, great strength, limited flexibility.
• Function: Muscles ko bones se connect karta hai (Muscle to Bone).

1. Cartilage:

• Matrix: Solid matrix jo proteins aur sugars se bani hoti hai.
• Characteristics: Widely spaced cells, flexible.
• Location: Joints par bone surfaces ko smoothen karta hai, nose, ear, trachea, larynx mein present hota hai.
• Function: Support aur flexibility provide karta hai.

1. Areolar Connective Tissue:

• Location: Skin aur muscles ke beech, blood vessels aur nerves ke around, bone marrow mein.
• Function: Organs ke andar space fill karta hai, internal organs ko support karta hai, tissue repair mein help karta hai.

1. Adipose Tissue:

• Characteristics: Fat-storing tissue, cells fat globules se bhare hote hain.
• Location: Skin ke neeche, internal organs ke beech.
• Function: Fat storage (energy reserve), insulation (heat loss se bachata hai), cushioning (organs ko protect karta hai).

Muscular tissue elongated cells (muscle fibres) se bana hota hai aur body mein movement ke liye responsible hota hai. Ismein special contractile proteins hote hain jo contract aur relax karte hain.

• Types of Muscular Tissue:

1. Striated Muscles (Skeletal Muscles/Voluntary Muscles):

• Control: Voluntary (humari ichha se move karte hain).
• Structure: Long, cylindrical, unbranched, multinucleate (kai nuclei), alternate light aur dark bands (striations) hote hain.
• Location: Limbs mein (bones se attached), body movement mein help karte hain.
• Function: Body movements.

1. Unstriated Muscles (Smooth Muscles/Involuntary Muscles):

• Control: Involuntary (humari ichha se control nahi hote).
• Structure: Long, spindle-shaped (pointed ends), uninucleate (single nucleus), no striations.
• Location: Alimentary canal (food movement), blood vessels, iris of eye, ureters, bronchi of lungs.
• Function: Internal organ movements (e.g., peristalsis).

1. Cardiac Muscles (Heart Muscles):

• Control: Involuntary (humari ichha se control nahi hote).
• Structure: Cylindrical, branched, uninucleate, faint striations.
• Location: Sirf heart mein paye jaate hain.
• Function: Rhythmic contraction aur relaxation throughout life, blood pump karte hain.

Summary Table: | Feature | Striated Muscle | Unstriated Muscle | Cardiac Muscle | |---|---|---|---| | Control | Voluntary | Involuntary | Involuntary | | Shape | Cylindrical | Spindle-shaped | Cylindrical, branched | | Nuclei | Multinucleate | Uninucleate | Uninucleate | | Striations | Present | Absent | Faintly present | | Branching | Unbranched | Unbranched | Branched | | Location | Limbs, attached to bones | Internal organs (gut, blood vessels) | Heart | | Function | Body movement | Involuntary movements of organs | Pumping blood |

Nervous tissue cells (neurons) se bana hota hai jo stimuli receive aur transmit karne mein highly specialized hote hain. Ye body mein information ko rapidly ek jagah se doosri jagah tak le jaate hain.

• Components:
• Brain: Nervous tissue ka main part.
• Spinal Cord: Brain se connect hokar body mein signals transmit karta hai.
• Nerves: Neurons ke bundles jo body ke alag-alag parts tak extend karte hain.

• Neuron (Nerve Cell) Structure:
• Cell Body (Cyton/Soma): Nucleus aur cytoplasm contain karta hai.
• Dendrites: Cell body se nikalne wale short, branched, hair-like processes. Ye stimuli receive karte hain.
• Axon: Usually ek single, long process jo cell body se nikalta hai. Ye nerve impulse ko transmit karta hai cell body se door.
• Nerve Endings: Axon ke end par hote hain, jahan se impulse dusre neuron ya effector organ tak jaata hai.

• Nerve Impulse:
• Signal jo nerve fibre ke along pass hota hai.
• Dendrites stimuli receive karte hain, cell body tak le jaate hain, aur phir axon ke through nerve endings tak transmit karte hain.
• Ek neuron ke nerve endings se impulse dusre neuron ke dendrites tak transmit hota hai.

• Function:
• Stimuli ko respond karna.
• Body ke andar signals ko transmit karna (e.g., muscle movement, sensory perception).
• Nerve aur muscle tissue ka functional combination animals ko stimuli ke response mein rapidly move karne mein enable karta hai.