🧬 Chapter 6: Tissues (Tissue – ऊत्तक)
🔸 Tissue kya hota hai?
Jab ek jaise cells (कोशिकाएँ) मिलकर कोई एक जैसा काम करते हैं, तो उन्हें Tissue कहा जाता है।
👉 Jaise – muscles cells मिलकर movement करते हैं, blood cells मिलकर चीज़ों को body में पहुँचाते हैं।
✅ Tissue banne se body ka kaam आसान और efficient ho जाता hai.
🌿 Plant Tissues (Paudhon ke Tissues)
🔹 1. Meristematic Tissue (विकसनशील ऊतक)
Yeh tissues divide (बंटने) karte hain aur naye cells banate hain. Ye plant ke grow karne mein madad karte hain.
🧪 Teen types ke hote hain:
- Apical Meristem – roots & stem ke tips par, plant ki length badhata hai.
- Intercalary Meristem – nodes par, leaves aur branches ko badhata hai.
- Lateral Meristem (Cambium) – stem ki चौड़ाई (girth) badhata hai.
🟡 Inke cells chhote, dense cytoplasm wale hote hain aur inme vacuole nahi hota.
🔹 2. Permanent Tissue (स्थायी ऊतक)
Jab meristematic cells divide karna बंद कर देते हैं, to wo permanent tissue ban jaate hain.
➤ (i) Simple Permanent Tissue
| Type | Features | Kya kaam karta hai |
|---|---|---|
| Parenchyma | Living cells, soft, intercellular space | Food store karta hai |
| Collenchyma | Living cells, corner thick | Flexibility deta hai (leaf stalks) |
| Sclerenchyma | Dead cells, hard & thick | Plant ko मजबूती (strength) deta hai |
➤ (ii) Complex Permanent Tissue
Ek se zyada type ke cells milkar banta hai, transport ka kaam karta hai.
- Xylem – water aur minerals ko roots se upar transport karta hai
➤ Tracheids, Vessels, Fibres, Parenchyma - Phloem – food ko leaves se sab jagah le jaata hai
➤ Sieve tubes, Companion cells, Fibres, Parenchyma
🔹 Epidermis (बाहरी सुरक्षा परत)
- Plant ke bahar ka protective cover hota hai.
- Isme hote hain:
- Stomata – छोटे pores jahan se plant gases exchange karta hai.
- Guard Cells – stomata ko खोलते और बंद करते हैं।
- Cuticle layer – paani loss se बचाव करती है (specially desert plants mein).
🔹 Cork (Bark – बाहरी परत)
- Purane plant part mein epidermis ki jagah cork ban jaata hai.
- Cork ke cells dead hote hain aur pani aur hawa se impermeable hote hain.
🧍♂️ Animal Tissues (Manav Tissues)
🔹 1. Epithelial Tissue (रक्षक ऊतक)
Ye covering tissue hai, jo body ke parts aur organs ko cover karta hai.
| Type | Kahan milta hai | Kaam |
|---|---|---|
| Squamous | Blood vessels, lungs | Thin layer for exchange |
| Stratified Squamous | Skin | Protection from damage |
| Cuboidal | Kidney, glands | Support, secretion |
| Columnar | Intestine | Absorption |
| Ciliated Columnar | Respiratory tract | Mucus ko हटाना |
| Glandular | Glands | Secretions banana |
🔹 2. Connective Tissue (जोड़ने वाला ऊतक)
Body ke parts ko connect karta hai.
| Tissue | Kaam |
|---|---|
| Blood | Oxygen, food, waste ko body mein le jaana |
| Bone | Body ka structure aur support |
| Cartilage | Nose, ear, joints mein smooth movement |
| Ligament | Bone to bone जोड़ता है |
| Tendon | Muscle to bone जोड़ता है |
| Areolar | Organs ko support karta hai |
| Adipose | Fat store karta hai, insulate karta hai |
🔹 3. Muscular Tissue (मांसपेशीय ऊतक)
Movement ke liye responsible hai. Contractile proteins isme hote hain jo muscles ko सिकोड़ते और फैलाते हैं।
| Type | Control | Shape | Kahan hota hai |
|---|---|---|---|
| Striated (Voluntary) | Apni marzi se | Cylindrical, many nuclei | Arms, legs |
| Smooth (Involuntary) | Automatically | Spindle-shaped, one nucleus | Stomach, intestine |
| Cardiac | Involuntary | Branched, 1 nucleus | Heart |
🔹 4. Nervous Tissue (तंत्रिका ऊतक)
Nervous tissue body ke अलग-अलग parts ko signal bhejne ka kaam karta hai.
- Neuron: Ek special cell hoti hai jisme:
- Cell body (nucleus hota hai)
- Dendrites (signals receive karte hain)
- Axon (signals bhejta hai)
🧠 Brain, spinal cord, aur nerves inhi neurons se milkar bante hain.
✍️ याद रखने लायक बातें:
- Tissue = Similar cells + same function
- Plant Tissue = Meristematic + Permanent
- Animal Tissue = Epithelial + Connective + Muscular + Nervous
- Xylem = पानी ले जाता है, Phloem = खाना
- Neuron = Signal bhejne wala cell
- Striated muscle = Voluntary movement, Cardiac muscle = heart mein