📘Class 10 Science – Chapter: Control and Coordination Notes
🧠 Introduction to Control and Coordination
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All organisms need to respond to stimuli for survival.
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Control and coordination in animals is carried out by the nervous system and endocrine system.
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In plants, it is through chemical coordination using plant hormones.
🧠 Nervous System in Humans
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Made up of brain, spinal cord, and nerves.
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Detects changes in the environment and responds accordingly.
Components:
| Component | Function |
|---|---|
| Receptors | Detect stimuli (e.g., eyes, skin, tongue) |
| Sensory neurons | Carry message from receptors to CNS |
| Motor neurons | Carry message from CNS to muscles/glands |
| Effectors | Muscles or glands that respond to stimuli |
Reflex Action:
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Quick, automatic response to a stimulus.
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Example: Withdrawing hand from a hot object.
Mechanism:
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Stimulus detected by receptor.
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Impulse travels via sensory neuron to spinal cord.
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Interneuron processes and sends message via motor neuron.
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Effector acts immediately.
Human Brain:
| Part | Function |
|---|---|
| Cerebrum | Intelligence, memory, voluntary actions |
| Cerebellum | Balance and coordination |
| Medulla | Controls involuntary activities (heartbeat, breathing) |
| Hypothalamus | Regulates body temperature, hunger, thirst |
Protection:
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Brain is protected by skull and cerebrospinal fluid (CSF).
🌱 Coordination in Plants
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Plants do not have a nervous system but respond using hormones (plant growth regulators).
Plant Movements:
| Type | Description | Example |
|---|---|---|
| Tropic Movement | Directional, in response to stimulus | Roots growing downward |
| Nastic Movement | Non-directional, immediate response | Touch-me-not leaves folding |
Plant Hormones:
| Hormone | Function |
|---|---|
| Auxin | Cell elongation, phototropism |
| Gibberellin | Stem elongation, seed germination |
| Cytokinin | Cell division, delays aging |
| Abscisic Acid | Inhibits growth, causes leaf fall (stress hormone) |
| Ethylene | Ripening of fruits |
🔁 Endocrine System in Humans
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Works through hormones secreted by endocrine glands directly into blood.
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Regulates long-term processes like growth, metabolism, reproduction.
Major Endocrine Glands:
| Gland | Hormone | Function |
|---|---|---|
| Pituitary | Growth hormone | Controls growth, master gland |
| Thyroid | Thyroxine | Regulates metabolism |
| Pancreas | Insulin, Glucagon | Maintains blood sugar levels |
| Adrenal | Adrenaline | Prepares body for emergency (fight or flight) |
| Testes (male) | Testosterone | Controls male secondary sexual characters |
| Ovaries (female) | Estrogen, Progesterone | Regulates female reproductive cycle |
Example:
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Low insulin production causes Diabetes.
⚙️ Coordination Between Nervous and Endocrine System
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Hypothalamus in brain controls pituitary gland.
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Pituitary regulates other endocrine glands.
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Together they maintain homeostasis.