Class 10 Ch 6 Control & Coordination

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Control and Coordination – 5-Page Study Notes
Ch-6: Control & Coordination 🧠
1. Introduction (परिचय)
  • Living organisms respond to environmental changes.
  • Animals: Controlled by Nervous & Muscular tissues.
  • Plants: Controlled by chemical signals (Hormones).
  • Receptors: Specialised tips of nerve cells that detect information (e.g., Gustatory $\to$ Taste, Olfactory $\to$ Smell).
2. The Neuron (तंत्रिका कोशिका)

Fundamental unit of the nervous system.

Structure of a Neuron

Dendrite Axon
  • Dendrite: Receives chemical information.
  • Axon: Transmits electrical impulse.
  • Synapse: Gap between two neurons where electrical signal is converted to chemical.
3. Reflex Action (प्रतिवर्ती क्रिया)
  • Sudden response to a stimulus (e.g., pulling hand from hot plate).
  • Reflex Arc: Pathway taken by nerve impulses in a reflex action.
  • IMP: Reflex arcs are formed in the Spinal Cord first for speed, though info goes to the brain!
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4. The Human Brain (मानव मस्तिष्क)

Main coordinating centre of the body.

Fig: Human Brain Sections

Forebrain Midbrain Hindbrain (Pons, Medulla, Cerebellum)
  • Forebrain (अग्र-मस्तिष्क): Main thinking part. Responsible for intelligence, memory, hearing, smell, and sight.
  • Midbrain: Controls reflex movements of head, neck, and trunk in response to visual/auditory stimuli.
  • Hindbrain (पश्च-मस्तिष्क):
    • Cerebellum: Precision & Body balance (e.g., walking in straight line).
    • Medulla: Involuntary actions (Blood pressure, Salivation, Vomiting).
5. Protection of CNS
  • Brain: Sits inside a bony box called Cranium. Floating in fluid-filled balloon (CSF – Cerebrospinal Fluid) for shock absorption.
  • Spinal Cord: Protected by the Vertebral Column (backbone).
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Thinking…
6. Coordination in Plants

Plants have neither a nervous system nor muscles.

  • Immediate Response: Movement not dependent on growth.
    उदाहरण: छुई-मुई (Mimosa pudica) की पत्तियों का मुड़ना।
  • Mechanism: Cells change shape by changing the amount of water in them (Turgor pressure).
7. Movement due to Growth (Tropic Movements)
  • Phototropism: Response to light. Shoot $\to$ (+), Root $\to$ (-).
  • Geotropism: Response to gravity. Root $\to$ (+), Shoot $\to$ (-).
  • Hydrotropism: Response to water.
  • Chemotropism: Response to chemicals (e.g., growth of pollen tube towards ovule).

Fig: Phototropism in Shoot

Light Shoot bending
Nastic vs Tropic: Nastic movements are non-directional (Touch-me-not), while Tropic movements are directional (Light, Gravity).
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8. Plant Hormones (Phytohormones)

पादप हार्मोन पौधों की वृद्धि और विकास को नियंत्रित करते हैं।

Hormone Major Function
Auxin (ऑक्सिन) Helps cells grow longer. Responsible for phototropism (accumulates on shaded side).
Gibberellins Help in the growth of the stem.
Cytokinins Promote Cell Division. Found in high concentration in fruits/seeds.
Abscisic Acid Growth Inhibitor. Causes wilting of leaves.
9. Mechanism of Auxin Action
  • When light comes from one side, auxin diffuses towards the shaded side of the shoot.
  • This concentration of auxin stimulates the cells to grow longer on that side.
  • Result: The plant appears to bend towards light.
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10. Hormones in Animals (Endocrine System)
  • Chemical messengers secreted by Endocrine Glands directly into blood.
Key Animal Hormones:
1. Adrenaline: (Adrenal Gland) “Fight or Flight”. Increases heart rate/blood flow to muscles.
2. Thyroxin: (Thyroid) Regulates carb, protein, fat metabolism. Needs Iodine.
(Deficiency $\to$ Goitre/घेंघा रोग)
3. Growth Hormone: (Pituitary) Controls growth/development.
(Deficiency $\to$ Dwarfism | Excess $\to$ Gigantism)
4. Insulin: (Pancreas) Regulates Blood Sugar level.
(Deficiency $\to$ Diabetes)
5. Testosterone/Oestrogen: Changes at puberty.
11. Feedback Mechanism (पुनर्भरण क्रियाविधि)
  • The timing and amount of hormone released is regulated by feedback mechanisms.
  • Example: Sugar levels rise in blood $\implies$ Detected by Pancreas $\implies$ Secretes more Insulin $\implies$ Sugar levels fall $\implies$ Insulin secretion reduced.
12. Chapter Summary
Nervous System (Fast but localized)
+
Hormonal System (Slow but persistent)
= COORDINATION
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