Class 10 Science

Chapter 6: Control and Coordination

Learn how the nervous system, brain, plant hormones, and endocrine glands work together to keep living organisms responsive and balanced.

🌐 Language / भाषा:

Remember from before:

In Class 9, we learned that nervous tissue coordinates body movements and responds to stimuli. Class 9 में, हमने सीखा था की nervous tissue body movements को coordinate करता है और stimuli के according respond करता है.
We saw that specialized cells called neurons are structural and functional units of nervous tissue. हमने देखा की specialized cells जिन्हें neurons kehte हैं, वह nervous tissue की structural और functional units होती हैं.
Visible movements (like a cat running, swings going up and down) are often responses to changes in the environment to keep the organism safe. Visible movements (जैसे cat का run करना, swings का up-down होना) hamare surroundings के changes का response होती हैं जो हमें safe रखता है.

1. Animals - Nervous System 1. जंतु (Animals) - Nervous System (जंतु-nervous तंत्र)

Section Goal: Explain how nervous tissue detects environmental stimuli and transmits electrical impulses from neurons to muscle cells. Section Goal: nervous ऊतक (Nervous tissue) कैसे environmental stimuli को detect करता है और neurons से muscle cells तक electrical impulses को transmit करता है, ise समझें.

🔌 The Telegraph Network Analogy

Imagine a school building with wires running from every classroom to a central speaker. The sensory receptors are like microphones, the neurons are the copper wires carrying electrical signals, and the muscles are speakers that play the sound. The nervous system is a fast-speed biological wire network. एक school building की कल्पना करें जहाँ हर classroom से wires एक central speaker तक ja रही हैं. Sensory receptors (ग्राही) microphones की tarah हैं, neurons copper wires की तरह हैं जो electrical signals ले जाती हैं, और muscles speakers की तरह हैं जो sound play करते हैं. हमारा nervous system एक fast-speed biological wire network की तरह है.

All information from our environment is detected by the specialized tips of some nerve cells, which are called receptors [NCERT पेज 99]. These receptors are located in our sense organs: हमारे environment की सारी information nerve cells की specialized tips द्वारा detect की जाती है, जिन्हें receptors (ग्राही) कहते हैं [NCERT पेज 99]। ये receptors हमारे sense organs में होते हैं:

Gustatory receptors (रससंवेदी ग्राही) detect taste [NCERT पेज 99]. Gustatory receptors (रससंवेदी ग्राही) taste detect करते हैं [NCERT पेज 99]।
Olfactory receptors (घ्राणग्राही) detect smell [NCERT पेज 99]. Olfactory receptors (घ्राणग्राही) smell detect करते हैं [NCERT पेज 99]।
Photoreceptors in eyes detect light, and Phonoreceptors in ears detect sound. Eyes में present photoreceptors light detect करते हैं, और ears में present phonoreceptors sound detect करते हैं.

A neuron (तंत्रिका कोशिका) is the functional unit of the nervous system. Information acquired at the dendritic tip of a neuron sets off a chemical reaction that creates an electrical impulse [NCERT पेज 100]. एक neuron (nervous cell) nervous system की basic functional unit है. Neuron के dendritic tip पर mili information एक chemical reaction को start करती है जिससे एक electrical impulse create होता है [NCERT पेज 100]।

3D Neuromuscular Junction Synapse Render — Source: Adapted from NCERT Class 10 Science, Fig 6.1 (b) Neuromuscular Junction, p. 100.

The electrical impulse travels from the dendrite to the cell body (Cyton) and then along the axon to its end [NCERT पेज 100]. At the end of the axon, the electrical impulse sets off the release of some chemical neurotransmitters. These chemicals cross the gap, called a synapse, and start a similar electrical impulse in the next neuron's dendrite [NCERT पेज 100]. ये electrical impulse dendrite से cell body (Cyton) तक travel करता है और फिर axon से होते हुए उसके end तक पहुंचता है [NCERT पेज 100]। Axon के end पर, electrical impulse chemical neurotransmitters को release करता है. ये chemicals दोनों nerve cells के बीच के gap, जिसे synapse (अंतर्ग्रथन) कहते हैं, को cross करते हैं और next neuron के dendrite में एक similar electrical impulse start करते हैं [NCERT पेज 100]।

Finally, when the nerve impulse reaches a muscle, the muscle must move. A neuromuscular junction is the junction where the nerve ending meets a muscle fiber [NCERT पेज 100]. Muscle cells change their shape to cause movement. They have special proteins that change their shape and arrangement in the cell in response to electrical impulses, causing contraction [NCERT पेज 102]. Finally, जब nerve impulse muscle तक पहुंचता है, तो muscle move करती है. Neuromuscular junction (nervous-muscle संधि) वह point है जहाँ nerve ending एक muscle fiber से मिलती है [NCERT पेज 100]। Movement के लिए muscle cells अपना shape बदलती हैं. उनके पास special proteins होते हैं जो electrical impulses के response में अपना shape और cell में अपना arrangement बदलते हैं, jisse contraction होता है [NCERT पेज 102]।

🔬 Lab 1: Virtual Neuron Synaptic Cleft 🔬 Lab 1: Virtual Neuron Synaptic Cleft (सिनैप्स लैब)

Drag the slider below to propagate an electrical signal along a nerve fiber and watch it cross the chemical synapse cleft to stimulate the next neuron. Nerve fiber के along electrical signal send करने के लिए slider को drag करें और देखें कैसे ये chemical synapse cleft को cross करके next neuron को stimulate करता है.

Signal Progress: 0%

⚡ Checkpoint 1 ⚡ Checkpoint 1

Which receptors are specialized to detect taste and smell respectively? Taste और smell को detect करने के लिए कौनसे specialized receptors उसे होते हैं?

📝 Section Summary

Receptors like gustatory (taste) and olfactory (smell) detect information from our surroundings. Gustatory (taste) और olfactory (smell) जैसे receptors हमारे surrounding से information detect करते हैं.
Impulses travel electrically down the dendrite, cyton, and axon, then cross the synapse gap chemically via neurotransmitters. Impulses electrically travel करते हैं down थे dendrite, cyton, और axon, और synapse gap को chemical neurotransmitters के through cross करते हैं.
Muscles contract when receiving nerve impulses by changing the shape and layout of their specialized proteins. Nerve impulses मिलने पर muscles specialized proteins का shape और arrangement बदलकर contract करती हैं.

2. Reflex Actions 2. Reflex Actions (प्रतिवर्ती action)

Section Goal: Trace the pathway of a reflex arc and explain why automatic reflex actions bypass conscious brain processing for survival. Section Goal: Reflex arc के pathway को trace करें और समझें की survival के लिए automatic reflex actions brain के conscious process bypass क्यों करते हैं.

🚨 The Smoke Detector & Automatic Sprinkler

If a room catches fire, the automatic water sprinkler goes off immediately on its own. It does not wait for a fire truck to arrive or for a committee to vote. A reflex action is your body's automatic local sprinkler—acting instantly to prevent damage before the brain finishes thinking. अगर किसी room में आग लग जाए, तो automatic पानी (water) sprinkler तुरंत खुद-b-खुद चल जाता है. वह fire truck के आने या किसी committee की permission का wait नहीं करता. एक reflex action भी आपकी body का automatic sprinkler है—जो brain के sochne से पहले ही damage rokne के लिए instantly act करता है.

A reflex action is a sudden, involuntary response to an environmental stimulus, such as pulling your hand back instantly when touching a hot flame [NCERT पेज 100]. एक reflex action (प्रतिवर्ती action) environmental stimulus के लिए एक sudden और involuntary response है, जैसे hot flame को touch करते ही hand को instantly peeche kheench lena [NCERT पेज 100]।

Thinking is a complex process involving dense networks of thousands of neurons in the brain. If we touched a hot object and waited for our brain to think "it is hot, I should move my hand," the tissue would burn. To prevent this, the connection between input (sensory) nerves and output (motor) nerves is made directly in the spinal cord [NCERT पेज 101]. Thinking एक complex process है जिसमें brain के thousands of neurons का network काम करता है. अगर हम किसी hot object को touch करें और brain के sochne का wait करें की "ये garm है, mujhe hand hatana chahiye", तो tissue burn हो jayega. इस damage को rokne के लिए, input (sensory) nerves और output (motor) nerves का connection direct spinal cord (मेरुरज्जु) में कर किया जाता है [NCERT पेज 101]।

The pathway that detects a stimulus, routes it through the spinal cord, and activates an effector muscle is called a reflex arc [NCERT पेज 101]. Stimulus को detect करने, उसे spinal cord के through route करने, और effector muscle को activate करने वाले pathway को reflex arc (प्रतिवर्ती चाप) कहते हैं [NCERT पेज 101]।

The Reflex Arc Sequence:
Stimulus (Heat) → Receptor (Skin) → Sensory Neuron → Spinal Cord (Relay Neuron) → Motor Neuron → Effector (Muscle) → Response (Pull hand away) [NCERT पेज 101]. थे Reflex Arc Sequence:
Stimulus (Garm) → Receptor (Skin) → Sensory Neuron → Spinal Cord (Relay Neuron) → Motor Neuron → Effector (Muscle) → Response (Hand hatana) [NCERT पेज 101]।

🔬 Lab 2: Interactive Reflex Arc Timeline 🔬 Lab 2: Interactive Reflex Arc Timeline (रिफ्लेक्स आर्क लैब)

Click the "Stimulate" button to send an emergency electrical impulse through the reflex arc and see how the spinal cord triggers muscle contraction before the brain is notified. "Stimulate" button पर click करके reflex arc के through impulse send करें और देखें कैसे spinal cord brain को पाता चलने से पहले ही muscle contraction trigger कर देता है.

⚡ Checkpoint 2 ⚡ Checkpoint 2

What is the correct pathway sequence of an electrical impulse in a reflex arc? Reflex arc में electrical impulse का correct pathway sequence kya है?

📝 Section Summary

Reflex actions bypass the conscious brain networks to allow rapid, life-saving responses to danger. Reflex actions conscious brain networks को bypass करते हैं ताकि danger के time rapid और life-saving response mil सके.
Reflex arcs are formed in the spinal cord, and sensory signals are simultaneously sent up to the brain. Reflex arcs spinal cord में बनते हैं, और sensory signals simultaneously brain तक भी bheje जाते हैं.
The sequence is: Receptor → Sensory Neuron → Spinal Cord → Motor Neuron → Effector Muscle. Correct sequence है: Receptor → Sensory Neuron → Spinal Cord → Motor Neuron → Effector Muscle.

3. Human Brain 3. मानव brain (Human Brain) (मानव brain)

Section Goal: Identify the three major divisions of the brain and describe how each anatomical region regulates voluntary and involuntary bodily functions. Section Goal: Brain के teen major divisions की pehchan करें और समझें की हर region voluntary और involuntary functions को कैसे control करता है.

🏢 The Corporate Headquarters Analogy

Think of the brain as a massive headquarters office:
• Forebrain (Cerebrum) is the CEO's office, where voluntary, conscious plans, memory, and thoughts are decided.
• Midbrain & Hindbrain (Pons, Medulla) are the maintenance basements controlling automatic utilities (AC, power grid, breathing, heartbeat) in the background.
• Cerebellum is the fitness trainer ensuring employees walk in straight lines and maintain perfect balance. Brain को एक massive corporate headquarters office की तरह समझें:
• Forebrain (Cerebrum) CEO का office है, जहाँ voluntary और conscious plans, memory, और thoughts decide होते हैं.
• Midbrain & Hindbrain (Pons, Medulla) maintenance basements हैं जो background में automatic utilities (breathing, heartbeat) को control करते हैं.
• Cerebellum fitness trainer है जो ensure करता है की आप straight line में चलें और body balance maintain rakhein.

The brain and spinal cord constitute the Central Nervous System (CNS) [NCERT पेज 101]. The peripheral nerves arise from the CNS: Cranial nerves originate from the brain, and Spinal nerves originate from the spinal cord [NCERT पेज 101]. Brain और spinal cord मिलकर Central Nervous System (CNS) (central nervous तंत्र) बनाते हैं [NCERT पेज 101]। Isse peripheral nerves निकलती हैं: Cranial nerves brain से originate होती हैं, और Spinal nerves spinal cord से originate होती हैं [NCERT पेज 101]।

3D Human Brain Anatomical sagittal view — Source: Adapted from NCERT Class 10 Science, Fig 6.3 Human Brain, p. 102.

The brain is divided into three major anatomical regions: Brain को teen major anatomical regions में divide किया गया है:

A. Forebrain (अग्रमस्तिष्क) A. Forebrain (अग्रbrain)

The forebrain consists mainly of the Cerebrum (प्रमस्तिष्क). It is the main thinking part of the brain and controls all voluntary actions [NCERT पेज 101]. It contains sensory areas for hearing, smell, sight, and separate areas for learning and memory [NCERT पेज 101]. It also houses the hunger center that senses when we are full [NCERT पेज 102]. Forebrain main part Cerebrum (प्रbrain) से बना होता है. यह brain का main thinking area है जो सारी voluntary actions को control करता है [NCERT पेज 101]। Isme hearing, smell, sight के लिए sensory areas होते हैं, और learning और memory के लिए separate areas होते हैं [NCERT पेज 101]। Isme hunger center भी होता है जो feed complete hone पर fullness feel कराता है [NCERT पेज 102]।

B. Midbrain (मध्यमस्तिष्क) & Hindbrain (पश्चमस्तिष्क) B. Midbrain (मध्यbrain) & Hindbrain (पश्चbrain)

These regions control involuntary actions (like pupil size changes, salivation, heartbeat) [NCERT पेज 102]. The hindbrain is split into three specific parts: ये regions involuntary actions (जैसे pupil size change होना, salivation, heartbeat) control करते हैं [NCERT पेज 102]। Hindbrain teen parts में split होता है:

Pons (पोंस) regulates respiration [NCERT पेज 102]. Pons (पोंस) respiration (respiration) को regulate करता है [NCERT पेज 102]।
Medulla (मध्यांश) controls blood pressure, salivation, and vomiting reflexes [NCERT पेज 102]. Medulla (मध्यांश) blood pressure, salivation, और vomiting reflexes को control करता है [NCERT पेज 102]।
Cerebellum (अनुमस्तिष्क) is responsible for precision of voluntary actions and maintaining posture and body balance (like walking in a straight line, riding a bicycle, or picking up a pencil) [NCERT पेज 102]. Cerebellum (अनुbrain) voluntary actions की precision और body posture और balance maintain करने के लिए responsible है (जैसे straight line में चलना, bicycle चलाना, ya pencil उठाना) [NCERT पेज 102]।

C. Protection of the CNS C. Protection of थे CNS (सुरक्षा)

Because the brain is extremely delicate, it sits inside a bony box called the cranium (कपाल) [NCERT पेज 102]. Within the skull, the brain is suspended in a fluid-filled balloon containing Cerebrospinal Fluid (CSF), which acts as a shock absorber [NCERT पेज 102]. The spinal cord is protected by the vertebral column or backbone [NCERT पेज 102]. क्योंकि brain बहुत delicate है, ये एक bony box के अंदर safe रहता है जिसे cranium (कपाल) कहते हैं [NCERT पेज 102]। Skull के अंदर, brain fluid-filled balloon के अंदर suspended होता है jisme Cerebrospinal Fluid (CSF) होता है, जो shock absorber का kaam करता है [NCERT पेज 102]। Spinal cord को vertebral column या backbone (कशेरुका दंड) protect करती है [NCERT पेज 102]।

🔬 Lab 3: Brain Function Mapping Atlas 🔬 Lab 3: Brain Function Mapping Atlas (brain मानचित्र)

Click on the buttons below to highlight different regions of the brain and discover what voluntary and involuntary actions they regulate. Brain के different regions को highlight करने के लिए buttons पर click करें और जानें की वह voluntary और involuntary actions को कैसे regulate करते हैं.

Select a Brain Region Brain का Region चुनें (ब्रेन का हिस्सा चुनें)

Click on one of the colored buttons above to see how that specific section of the central nervous system controls thoughts, movements, or automatic survival reflexes. ऊपर दिए गए colored buttons पर click करके देखें की central nervous system का वह part thoughts, movements या automatic survival reflexes को कैसे control करता है.

⚡ Checkpoint 3 ⚡ Checkpoint 3

Which part of the hindbrain controls posture and balance during voluntary movements like riding a bicycle? Voluntary movements (जैसे bicycle चलाना) के time posture और body balance hindbrain का कौनसा part control करता है?

📝 Section Summary

The Forebrain (Cerebrum) is the center for thinking, decision making, voluntary actions, and memory. Forebrain (Cerebrum) thinking, decision making, voluntary actions, और memory का main center है.
The Hindbrain consists of the Pons (breathing), Medulla (vomiting, salivation, BP), and Cerebellum (balance, coordination). Hindbrain में Pons (breathing), Medulla (vomiting, saliva, BP), और Cerebellum (balance, coordination) होते हैं.
The brain is protected by a bony cranium skull and floating cerebrospinal fluid (CSF) shock absorbers. Brain cranium skull और floating cerebrospinal fluid (CSF) shock absorbers द्वारा protected रहता है.

4. Coordination in Plants 4. Coordination in पौधे (पादपों में समन्वय)

Section Goal: Contrast plant immediate responses (turgor changes) with slow directional growth (tropisms) driven by chemical phytohormones. Section Goal: पौधे के immediate responses (turgor changes) और slow directional growth (tropisms) के बीच difference समझें, जो chemical phytohormones द्वारा controlled होते हैं.

🌱 The Solar Tracker and Touch Sensor

Animals run away from danger using muscles. Plants cannot walk, so they move by growing. Bending towards a window is like an automatic solar panel slowly turning towards the sun. Folding leaves on a touch-sensitive plant (chhui-mui) is like deflating water balloons inside leaf joints, causing them to drop instantly. जंतु (Animals) muscles का उसे करके danger से भाग सकते हैं. पौधे चल नहीं सकते, इसलिए वह grow करके move करते हैं. Window की तरफ bend होना solar panel के sun की तरफ turn होने जैसा है. Touch-sensitive पौधा (chhui-mui) की पत्तियां का fold होना पत्ती joints के अंदर के पानी (water) balloons के deflate होने जैसा है, जिससे पत्तियां instantly drop हो जाती हैं.

Plants have neither a nervous system nor muscles [NCERT पेज 102]. They coordinate their actions through two distinct types of movements: पौधे के पास na तो nervous system होता है और na ही muscles [NCERT पेज 102]। वे दो distinct types के movements के द्वारा coordinate करते हैं:

A. Immediate Response to Stimulus (वृद्धि से मुक्त गति) A. Immediate Response to Stimulus (growth से मुक्त movement)

This movement is independent of growth [NCERT पेज 102]. When you touch the leaves of the sensitive plant (Mimosa pudica / छुई-मुई), they fold up immediately [NCERT पेज 102]. The plant uses electrochemical means to convey information from cell to cell. Instead of muscle proteins, plant cells change their shape by changing the amount of water in them—swelling (when water enters) or shrinking (when water leaves), causing the leaves to fold [NCERT पेज 103]. ये movement growth पर depend नहीं करती [NCERT पेज 102]। जब आप sensitive पौधा (Mimosa pudica / छुई-मुई) की पत्तियां को touch करते हैं, तो वे तुरंत fold हो जाती हैं [NCERT पेज 102]। पौधा cell-to-cell information convey करने के लिए electrochemical means उसे करते हैं. Muscle proteins के बिना, पौधा cells पानी (water) volume change karke अपना shape बदलती हैं—पानी (water) enter करने पर swell हो जाती हैं और exit करने पर shrink हो जाती हैं, जिससे पत्तियां fold होती हैं [NCERT पेज 103]।

3D Plant Tropisms Growth Diagrams — Source: Adapted from NCERT Class 10 Science, Fig 6.5 & 6.6 Phototropism and Geotropism, p. 104.

B. Directional Growth Movements — Tropisms (तटस्थ गतियां) B. Directional Growth Movements — Tropisms (तटस्थ movementयां)

These are growth movements in response to directional environmental stimuli [NCERT पेज 104]: ये growth movements directional environmental stimuli के response में होती हैं [NCERT पेज 104]:

Phototropism (प्रकाशानुवर्तन): Growth response to light. Shoots bend towards light (+), while roots bend away (-) [NCERT पेज 104]. Phototropism (प्रकाशानुवर्तन): Light के direction में response. तने (Stems) light की तरफ bend होते हैं (+), जबकि जड़ें light से दूर bend होती हैं (-) [NCERT पेज 104]।
Geotropism (गुरुत्वानुवर्तन): Response to gravity. Roots grow downwards (+), and shoots grow upwards (-) [NCERT पेज 104]. Geotropism (गुरुत्वानुवर्तन): Gravity के direction में response. जड़ें (Roots) नीचे grow करती हैं (+), और प्ररोह (shoots) ऊपर grow करते हैं (-) [NCERT पेज 104]।
Hydrotropism (जलाकर्षण): Roots grow towards water sources. Hydrotropism (जलाकर्षण): जड़ें (Roots) का moisture और पानी (water) sources की तरफ grow करना.
Chemotropism (रसायनअनुवर्तन): Response to chemicals, such as the growth of pollen tubes towards ovules during fertilization [NCERT पेज 104]. Chemotropism (रसायनअनुवर्तन): Chemicals के direction में growth response, जैसे fertilization के dauran pollen tubes का ovules की तरफ grow करना [NCERT पेज 104]।

C. Plant Hormones (Phytohormones / पादप हार्मोन) C. पौधा Hormones (Phytohormones / पादप हार्मोन)

Plants synthesize chemical compounds to coordinate growth and development [NCERT पेज 105]: पौधे growth और development coordinate करने के लिए chemical compounds synthesize करते हैं [NCERT पेज 105]:

Hormone Hormone (पादप हार्मोन)	Primary Biological Action Primary Biological Action (जैविक action)	NCERT Citation NCERT Citation
Auxin (ऑक्सिन) Auxin (ऑक्सिन)	Synthesized at shoot tip. Promotes cell elongation. Diffuses to the shaded side when light shines from one direction, causing cells on the dark side to grow longer, bending the stem towards light. Shoot tip पर synthesize होता है. Cell elongation को promote करता है. जब light एक side से आती है, तो ये shaded side में diffuse हो जाता है, जिससे dark side की cells लंबी grow करती हैं और stem light की तरफ bend हो जाता है.	[NCERT पेज 105]
Gibberellins (जिबरेलिन) Gibberellins (जिबरेलिन)	Help in the growth of the stem. तने (Stems) की length और growth में help करते हैं.	[NCERT पेज 105]
Cytokinins (साइटोकाइनिन) Cytokinins (साइटोकाइनिन)	Promote rapid cell division. Found in high concentrations in areas of rapid growth (fruits and seeds). Rapid cell division को promote करते हैं. Fruits और seeds जैसे zones में high concentration में मिलते हैं.	[NCERT पेज 105]
Abscisic Acid (एब्सिसिक अम्ल) Abscisic Acid (एब्सिसिक acid)	Inhibits growth. Causes wilting of leaves and closing of stomata during water stress. Growth को inhibit करता है. Leaves के murjhane (wilting) और dry times में stomata close करने के लिए responsible है.	[NCERT पेज 105]

🔬 Lab 4: Plant Tropism growth Sandbox 🔬 Lab 4: पौधा Tropism growth Sandbox (पादप ट्रॉपिज्म)

Adjust the direction of the light bulb using the slider to see how auxin accumulation on the shaded side causes cell elongation and bends the shoot towards the light. Light bulb की direction slider से change करें और देखें कैसे shaded side में auxin accumulation से cell growth बढ़ती है और stem bend हो जाता है.

Light Position (Left ↔ Right): Center

⚡ Checkpoint 4 ⚡ Checkpoint 4

Which plant hormone inhibits growth and is responsible for the wilting of leaves? कौनसा पौधा hormone growth को inhibit करता है और पत्तियां के wilting के लिए responsible है?

📝 Section Summary

Plant leaves fold immediately upon touch via local changes in turgor water pressure. Touch करने पर पानी (water) pressure (turgor pressure) के change होने से sensitive पत्तियां instantly fold हो जाती हैं.
Tropic growth responses curve stems towards light (phototropism) and roots downwards with gravity (geotropism). Directional tropic growth तने को light की तरफ curve करती है (phototropism) और जड़ें को gravity की तरफ (geotropism).
Hormones (Auxin, Gibberellins, Cytokinins) promote growth, while Abscisic Acid inhibits growth. Auxins, Gibberellins, और Cytokinins growth को promote करते हैं, जबकि Abscisic Acid growth inhibit करता है.

5. Animal Hormones 5. जंतु Hormones (जंतुओं में हार्मोन)

Section Goal: Explain how endocrine glands secrete hormones into the bloodstream and describe the feedback mechanisms that control hormone concentrations. Section Goal: Endocrine glands कैसे hormones को direct blood में secrete करती हैं और उनके level को feedback mechanisms से कैसे control किया जाता है, ise समझें.

✉️ The Wireless Radio Broadcast Analogy

Nerves are like copper telephone wires. The endocrine system is like a radio broadcast tower. Endocrine glands release chemical hormones directly into the blood river (the broadcast). Only cells with the correct matching protein antenna (receptors) receive the message and respond. Nerves copper telephone wires की तरह हैं. Endocrine system wireless radio broadcast tower की तरह है. Endocrine glands chemical hormones को direct blood river (circulation) में release करती हैं. सिर्फ वही cells response देती हैं जिनके पास correct matching protein receptor antenna होता है.

Hormones are chemical messengers secreted directly into the bloodstream by ductless endocrine glands to regulate metabolic and physiological activities [NCERT पेज 106]. Hormones chemical messengers होते हैं जो ductless endocrine glands (अंतःस्रावी ग्रंथियाँ) द्वारा direct blood stream में release किए jaate हैं, ताकि metabolic और physiological functions को regulate किया ja sake [NCERT पेज 106]।

3D Human Endocrine Glands anatomy map — Source: Adapted from NCERT Class 10 Science, Fig 6.7 Endocrine Glands in humans, p. 106.

Key Endocrine Glands and Their Hormones: प्रमुख Endocrine Glands और उनके Hormones (main अंतःस्रावी ग्रंथियां):

1. Adrenaline (एड्रीनालिन) - Adrenal Glands 1. Adrenaline (एड्रीनालिन) - Adrenal Glands

Secreted by adrenal glands during stress or emergency (the "fight-or-flight" response) [NCERT पेज 105].
Effects: Heart beats faster to supply more oxygen to muscles, breathing rate increases, and blood flow is diverted from the digestive system and skin to skeletal muscles [NCERT पेज 105]. Adrenal glands से emergency या stress के time secrete होता है (fight-or-flight response) [NCERT पेज 105]।
Effects: Heart beat तेज हो जाती है ताकि muscles को oxygen supply मिल सके, breathing rate बढ़ जाती है, और blood flow digestive tract और skin से divert होकर skeletal muscles तक पहुंचता है [NCERT पेज 105]।

2. Thyroxine (थाइरॉक्सिन) - Thyroid Gland 2. Thyroxine (थाइरॉक्सिन) - Thyroid Gland

Regulates carbohydrate, protein, and fat metabolism to provide the optimal balance for growth [NCERT पेज 105].
Iodine Requirement: Iodine is essential for the synthesis of thyroxine [NCERT पेज 105]. A deficiency of iodine in our diet leads to Goitre (घेंघा रोग), characterized by a swollen neck [NCERT पेज 106]. Growth को regulate करने के लिए carbohydrate, protein, और fat के metabolism को control करता है [NCERT पेज 105]।
Iodine Requirement: Thyroxine के synthesis के लिए iodine ज़रूरी है [NCERT पेज 105]। Diet में iodine की कमी से Goitre (घेंघा रोग) हो जाता है, जिसमें neck swell हो जाती है [NCERT पेज 106]।

3. Growth Hormone (वृद्धि हार्मोन) - Pituitary Gland 3. Growth Hormone (growth हार्मोन) - Pituitary Gland

Secreted by the pituitary gland (located at the base of the brain) to regulate growth and development [NCERT पेज 106].
Deficiency in childhood causes dwarfism (बौनापन), while excess causes gigantism (अतिदीर्घकाय) [NCERT पेज 106]. Brain के base पर located pituitary gland (पीयूष ग्रंथि) से secrete होता है और growth को regulate करता है [NCERT पेज 106]।
Childhood में इसकी deficiency से dwarfism (बौनापन) और excess से gigantism (अतिदीर्घकाय) हो जाता है [NCERT पेज 106]।

4. Insulin (इंसुलिन) - Pancreas 4. Insulin (इंसुलिन) - Pancreas

Produced by the pancreas to regulate blood glucose levels [NCERT पेज 107]. A deficiency in insulin production leads to Diabetes, where blood sugar levels rise to harmful levels [NCERT पेज 107]. Pancreas (अग्न्याशय) से produce होता है जो blood glucose levels को control करता है [NCERT पेज 107]। Insulin की कमी से Diabetes (मधुमेह) हो जाता है, जिसमें blood sugar level तेजी से बढ़ता है [NCERT पेज 107]।

Feedback Mechanism (पुनर्भरण क्रियाविधि) Feedback Mechanism (पुनर्भरण actionविधि)

It is crucial that hormones are secreted in precise quantities. The timing and amount of hormone release are regulated by chemical feedback mechanisms [NCERT पेज 107]. Hormones का body में right quantity में release होना ज़रूरी है. इसके timing और amount को feedback mechanisms (पुनर्भरण actionविधि) chemical control के through maintain करती हैं [NCERT पेज 107]।

When blood sugar levels rise, they are detected by cells of the pancreas, which respond by secreting more insulin [NCERT पेज 107]. As the blood sugar level falls to normal, insulin secretion is shut off [NCERT पेज 107]. E.g., जब blood sugar level बढ़ता है, तो pancreas की cells उसे detect करती हैं और insulin secretion बढ़ा देती हैं [NCERT पेज 107]। जैसे ही blood sugar level normal होता है, insulin secretion वापस shut off हो जाता है [NCERT पेज 107]।

🔬 Lab 5: Homeostasis Glucose Feedback Loop 🔬 Lab 5: Homeostasis Glucose Feedback Loop (होमियोस्टैसिस लैब)

Trigger actions below to see how insulin coordinates blood sugar regulation through a biological feedback loop. नीचे दिए buttons पर click करें और देखें कैसे body insulin और feedback loop से blood sugar regulate करती है.

⚡ Checkpoint 5 ⚡ Checkpoint 5

Which mineral is essential for the synthesis of the hormone thyroxine by the thyroid gland? Thyroid gland द्वारा thyroxine hormone के synthesis के लिए कौनसा mineral ज़रूरी है?

📝 Section Summary

Hormones are chemical coordinates released directly into the blood by endocrine glands. Hormones chemical coordinates हैं जो endocrine glands द्वारा direct blood stream में release होते हैं.
Thyroxine regulates metabolic speed and requires iodine; insulin regulates glucose and is secreted by the pancreas. Thyroxine body metabolic rate maintain करता है और उसे iodine चाहिए; insulin sugar regulate करता है और pancreas से secrete होता है.
Hormone concentration is tightly regulated by negative feedback loops that detect change and restore balance. Hormone concentration feedback loops द्वारा control होती है जो balance restore करने के लिए checks apply करती हैं.

NCERT Solutions NCERT Solutions (पाठ्यपुस्तक के हल)

Q1. What is the difference between a reflex action and walking? Q1. Reflex action और walking के बीच kya difference है?

Answer:

Reflex Action: It is a rapid, automatic, and involuntary response to sensory stimuli (e.g. pulling hand away from heat). It is controlled by the spinal cord and does not require conscious thinking. Reflex Action: यह एक rapid, automatic, और involuntary response है stimuli के response में (जैसे hot plate से hand hatana)। यह spinal cord द्वारा control होता है और isme conscious thinking की zaroorat नहीं होती.
Walking: It is a voluntary action coordinated by the brain (specifically the cerebellum in the hindbrain). It is a learned behavior that is controlled by conscious intent and complex muscular coordinates. Walking: ये एक voluntary action है जिसे brain (specifically hindbrain का cerebellum) coordinate करता है. Isme conscious intent और muscle coordination ज़रूरी है.

Q2. What happens at the synapse between two neurons? Q2. Do neurons के बीच synapse पर kya होता है?

Answer: At the end of the axon of the first neuron, the electrical impulse triggers the release of chemical messengers called neurotransmitters. These chemicals diffuse across the tiny physical gap (synapse) and bind to specific receptor sites on the dendrite of the next neuron. This binding sets off a new electrical impulse in the second neuron, allowing the signal to travel forward. Answer: First neuron के axon end पर, electrical impulse chemical messengers (neurotransmitters) को release करता है. ये chemicals tiny synaptic gap (synapse) के cross diffuse hokar next neuron के dendrite receptors पर bind होते हैं. इस binding से next neuron में एक naya electrical impulse start होता है, जिससे signal forward travel करता है.

Q3. Which part of the brain maintains posture and equilibrium of the body? Q3. Body का posture और balance (equilibrium) maintain करने के लिए brain का कौनसा part responsible है?

Answer: The Cerebellum, which is a part of the Hindbrain, is responsible for maintaining posture, body balance, and equilibrium during voluntary actions. Answer: Hindbrain का Cerebellum part body posture, physical balance, और equilibrium को coordinate करता है voluntary actions के dauran.

Q4. How do we detect the smell of an agarbatti (incense stick)? Q4. अगरबत्ती (incense stick) की smell hume कैसे detect होती है?

Answer: Agarbatti smoke carries chemical vapors which are detected by the olfactory receptors located inside our nasal chamber. These receptors trigger electrical impulses that travel along sensory neurons to the olfactory center in the forebrain (cerebrum). The cerebrum interprets this input and recognizes the smell based on previous memory. Answer: अगरबत्ती smoke के chemical vapors nasal chamber में present olfactory receptors (घ्राणग्राही) द्वारा detect किए jaate हैं. यह receptors electrical impulses coordinate करते हैं जो sensory neurons के raste forebrain के cerebrum section तक पहुंचते हैं, जहाँ previous memories के according smell की identity decode होती है.

Q5. What is the role of the brain in reflex action? Q5. Reflex actions में brain का kya role होता है?

Answer: The reflex action itself bypasses conscious brain processing and is executed directly via a reflex arc in the spinal cord for speed. However, the sensory pathway continues upwards to the brain. The brain registers the stimulus event, processes the sensation (e.g. pain), and stores the event in memory to prevent future encounters. Answer: Reflex action fast action के लिए conscious brain processing को bypass करके direct spinal cord के through coordinate होता है. लेकिन sensory information parallel में brain तक भी जाती है, ताकि brain pain register कर सके और इस incident की memory को future protection के लिए save rakh सके.

Q6. What are plant hormones? Q6. पौधा hormones (पादप हार्मोन) kya होते हैं?

Answer: Plant hormones (or phytohormones) are organic chemical substances synthesized in minute quantities in one part of a plant and translocated to other parts, where they coordinate growth, development, cell division, and responses to environmental stimuli. Examples: Auxin, Gibberellin, Cytokinin, and Abscisic Acid. Answer: पौधा hormones (या phytohormones) organic chemical substances होते हैं जो पौधे के parts में tiny quantities में synthesize होते हैं और different locations तक travel करके growth, cell division, development, और stimuli response coordinate करते हैं. E.g., Auxin, Gibberellin, Cytokinin, और Abscisic Acid.

Q7. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light? Q7. Sensitive पौधा (chhui-mui) की पत्तियां की movement shoot की phototropic movement से कैसे different है?

Answer:

Sensitive Plant (Chhui-mui) movement Sensitive पौधा (Chhui-mui) movement	Phototropic movement of shoot Phototropic movement of shoot
Growth-independent (Nastic movement). Growth-independent (Nastic movement - growth से मुक्त movement)।	Growth-dependent (Tropic movement). Growth-dependent (Tropic movement - growth पर निर्भर movement)।
Immediate response driven by turgor water pressure changes inside pulvini cells. Immediate response जो pulvini cells में पानी (water) volume (turgor pressure) के बदलने से होता है.	Slow growth curvature response driven by unequal distribution of the hormone auxin. Slow growth curvature response जो hormone auxin के unequal distribution के karan होता है.
Non-directional response to mechanical touch. Non-directional response जो किसी touch stimulus के response में होता है.	Directional response towards light source. Directional response जो light source की तरफ curve growth दिखाता है.

Q8. How does phototropism occur in plants? Q8. पौधे में phototropism (प्रकाशानुवर्तन) कैसे होता है?

Answer: Phototropism is driven by the hormone auxin. Auxin is synthesized at the shoot tips. When light falls on the plant from one side, auxin diffuses away from the light towards the shaded side of the stem. The higher concentration of auxin on the shaded side causes cells on that side to grow longer than those on the illuminated side, causing the stem tip to curve and bend towards the light. Answer: Phototropism hormone auxin द्वारा controlled होता है. Auxin shoot tips पर synthesize होता है. जब light एक side से आती है, तो auxin diffuse hokar shaded (dark) side में shift हो जाता है. Shaded side में auxin concentration high होने से wahan की cells normal cell से ज़्यादा elongation करती हैं, जिससे shoot tip light direction में curve हो जाता है.

Q9. How are the brain and spinal cord protected? Q9. Brain और spinal cord की protection कैसे होती है?

Answer:

The brain is housed within a rigid, bony structure called the cranium (skull) and suspended inside a fluid-filled balloon containing cerebrospinal fluid (CSF) which acts as a hydraulic shock absorber. Brain skull bony structure cranium (कपाल) के andar fluid-filled shock-absorbing Cerebrospinal Fluid (CSF) balloon में safe रहता है.
The spinal cord is enclosed and protected within the hard, articulated bony channel of the vertebral column (backbone). Spinal cord backbone channel vertebral column (कशेरुका दंड) के protective bony tunnel के andar safety paati है.

Q10. How does chemical coordination take place in animals? Q10. जंतु (Animals) में chemical coordination कैसे होता है?

Answer: Chemical coordination is mediated by hormones secreted by endocrine glands. These ductless glands release hormones directly into the blood circulation. Blood carries the hormones to target organs, where they bind to specific cell receptors, triggering metabolic changes that coordinate growth, blood pressure, sugar levels, and homeostasis. Answer: Chemical coordination endocrine glands से release होने वाले hormones के through होता है. ये ductless glands directly blood circulation में hormones release करती हैं. Blood इन hormones को target organs तक ले जाता है, जहाँ receptors से bind hokar ये growth, BP, blood sugar level, और homeostasis को coordinate करते हैं.

Q11. Why is the use of iodised salt recommended? Q11. Iodised salt (आयोडीन युक्त नमक) use करने की recommendation kyun di jaati है?

Answer: The thyroid gland requires iodine to synthesize the hormone thyroxine. Thyroxine is crucial for regulating carbohydrate, fat, and protein metabolism to promote balanced bodily growth. A lack of iodine in diet prevents thyroxine synthesis, causing Goitre, characterized by an enlarged, swollen thyroid gland. Answer: Thyroid gland को thyroxine hormone बनाने के लिए iodine ज़रूरी है. Thyroxine body growth के लिए fat, carbohydrate, और protein metabolism को balance करता है. Diet में iodine की कमी से Goitre हो जाता है, जिसमें neck region (thyroid) तेजी से swell हो जाती है.

Q12. How does our body respond when adrenaline is secreted into the blood? Q12. Adrenaline blood में release होने पर body कैसे respond करती है?

Answer: Adrenaline prepares the body for action under threat (fight-or-flight):

Heart rate and stroke volume increase, boosting blood oxygenation to skeletal muscles. Heart rate and pumping load बढ़ जाते हैं, ताकि skeletal muscles को continuous oxygen flow mil सके.
Respiration rate increases due to contraction of diaphragm and rib muscles. Diaphragm and rib muscles के heavy contraction से respiration rate बढ़ जाता है.
Blood supply to the skin and digestive system is constricted, diverting flow to active skeletal muscles. Digestive system और skin तो blood supply narrow (constrict) हो जाती है, ताकि blood major working muscles तक shift हो सके.
Starch conversion to glucose increases in the liver to supply immediate metabolic energy. Immediate metabolic energy output के लिए liver stored glycogen reserves को glucose में release करता है.

Solved PYQs Solved PYQs (विगत वर्षों के प्रश्न)

[1 Mark] Name the plant hormone that inhibits growth and causes wilting of leaves. [1 Mark] Growth inhibit करने वाले और पत्तियां की wilting के लिए responsible पौधा hormone का name बताएं.

Answer: Abscisic Acid (ABA) is the phytohormone responsible for growth inhibition and leaf wilting. Answer: Abscisic Acid (ABA) ही growth inhibition और पत्तियां wilting के लिए responsible पौधा hormone है.

[2 Marks] Mention two functions of the hormone insulin. Name the gland that secretes it. [2 Marks] Hormone insulin के do functions बताएं. उसे secrete करने वाली gland का name भी लिखें.

Answer:

It regulates blood glucose levels by promoting cellular glucose uptake. ये cells में glucose intake को regulate करके blood glucose level normal करता है.
It stimulates the liver to convert excess glucose into glycogen for storage. ये liver cells को excess sugar glycogen में store करने के लिए instructions देता है.

It is secreted by the pancreas.

[3 Marks] Trace the pathway of a nerve impulse through a reflex arc when you touch a hot plate. [3 Marks] Hot plate touch होने पर reflex arc के pathway को trace करें.

Answer:

Receptor (Skin of hand): Detects heat stimulus. Receptor (Skin): Heat stimulus detect करता है.
Sensory Neuron: Carries electrical impulse to spinal cord. Sensory Neuron: Impulse को spinal cord तक ले जाता है.
Relay Neuron (Spinal Cord): Receives sensory signal and immediately transfers it to motor neuron. Relay Neuron (Spinal Cord): Signal integrate करके motor neuron तक transfer करता है.
Motor Neuron: Carries response impulse back to effector muscle. Motor Neuron: Response command signal wapas muscle तक ले जाता है.
Effector (Bicep muscle): Muscle contracts, lifting the hand away from the hot plate. Effector (Bicep Muscle): Muscle contract hokar hand को hot plate से दूर pull करती है.

[5 Marks] List 5 endocrine glands, identify the hormone secreted by each, and state one key function for each. [5 Marks] 5 endocrine glands के name, उनके secreted hormones, और एक function की table बनाएं.

Answer:

Gland Gland (ग्रंथि)	Hormone Hormone (पादप हार्मोन)	Key Biological Function Key Biological Function (जैविक function)
Pituitary Pituitary (पीयूष ग्रंथि)	Growth Hormone Growth Hormone (growth हार्मोन)	Regulates overall body growth and skeletal development. Body height, growth, और bones development coordinate करता है.
Thyroid Thyroid (अवटु ग्रंथि)	Thyroxine Thyroxine (थाइरॉक्सिन)	Controls metabolic rates of carbohydrate, protein, and fat. Fat, carbohydrates, और proteins के metabolism को control करता है.
Adrenal Adrenal (अधिवृक्क ग्रंथि)	Adrenaline Adrenaline (एड्रीनालिन)	Prepares muscles and organs for emergency fight-or-flight reactions. Emergency conditions में blood pressure, breathing, और alert system activate करता है.
Pancreas Pancreas (अग्न्याशय)	Insulin Insulin (इंसुलिन)	Lowers blood sugar levels by aiding cellular glucose transport. Blood stream से glucose extraction regulate करके sugar lower करता है.
Testes / Ovaries Testes / Ovaries (वृषण / अंडाशय)	Testosterone / Estrogen Testosterone / Estrogen (टेस्टोस्टेरोन / एस्ट्रोजन)	Coordinates development of secondary sexual characters during puberty. Puberty transition के dauran secondary sexual characteristics control करते हैं.

Sources:

NCERT Class 10 Science, Chapter 6: Control and Coordination, pp. 99–112. NCERT Class 10 Science, Chapter 6: Control and Coordination, pp. 99–112.
CBSE Board Secondary Curriculum Class 10 Science Guidelines. CBSE Board Secondary Curriculum Class 10 Science Guidelines.