Class 10 Science — Chapter 6
Control and Coordination (Complete Ultra-Detailed Revision Notes)
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SECTION 1: INTRODUCTION & ANIMALS - NERVOUS SYSTEM (PAGE 1)
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* Introduction:
- All living organisms respond and react to various changes or stimuli in their environment
(like light, heat, cold, sound, touch, pressure).
- The working together of various organs in a systematic manner to produce a proper
response to a stimulus is called coordination.
- In animals, this control and coordination are performed by two main systems:
1. Nervous System (Nerves and Brain)
2. Endocrine System (Hormones)
* Receptors:
- Specialized tips of some nerve cells that detect information from the environment. They
are located in our sense organs:
- Phonoreceptors: Inner ear (Hearing and balance of the body)
- Photoreceptors: Eye (Visual stimulus / Sight)
- Olfactory Receptors: Nose (Smell detection)
- Gustatory Receptors: Tongue (Taste detection)
- Thigmoreceptors: Skin (Touch, heat, or cold)
* Neuron (Nerve Cell):
- The structural and functional unit of the nervous system.
- Parts of a Neuron:
1. Dendrite: Acquires the chemical information/stimulus from outside.
2. Cell Body (Cyton): Converts the information into an electrical impulse.
3. Axon: Longest part of a neuron; transmits the electrical impulse from the cell body to
the axon terminal.
- Synapse: The microscopic gap between the axon terminal of one neuron and the
dendrites of the next neuron. Here, the electrical impulse is converted into a chemical signal
(neurotransmitter) to cross the gap.
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SECTION 2: REFLEX ACTION & THE HUMAN BRAIN (PAGE 2)
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* Reflex Action:
- A sudden, unconscious, and involuntary response of the body to a dangerous stimulus.
- Example: Pulling back your hand immediately upon touching a hot object.
- Reflex Arc: The pathway taken by nerve impulses in a reflex action.
- Pathway: Stimulus (Hot Object) → Receptor (Skin) → Sensory Neuron → Spinal Cord →
Motor Neuron → Effector Organ (Muscle) → Response (Pulling hand back).
, - Note: Reflex actions are monitored and controlled by the Spinal Cord, not the brain, to
save time and prevent tissue damage.
* The Human Brain:
- The main coordinating center of the body. Protected inside a bony box called the cranium
(skull) and surrounded by cerebrospinal fluid (acts as a shock absorber).
- The brain is divided into three major regions:
1. Fore-brain (Cerebrum): The thinking part. Controls memory, learning, reasoning,
speech, and voluntary actions. It receives sensory impulses from various receptors.
2. Mid-brain: Controls involuntary actions like change in pupil size and reflex movements
of the head, neck, and trunk.
3. Hind-brain: Consists of three main components:
- Cerebellum: Controls posture, body balance, and precision of voluntary actions (e.g.,
walking in a straight line, riding a bicycle).
- Medulla: Controls involuntary actions like blood pressure, salivation, and vomiting.
- Pons: Regulates respiration and breathing cycles.
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SECTION 3: COORDINATION IN PLANTS (PAGE 3)
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* Plant Movements:
- Unlike animals, plants do not have a nervous system or muscles. They move and respond
using chemical means.
- Plant movements are of two main types:
1. Independent of Growth (Nastic Movements): Immediate response to a stimulus.
- Example: Drooping of leaves in a 'Touch-Me-Not' plant (Mimosa pudica) upon
touching. This happens due to sudden changes in the amount of water in leaf cells.
2. Dependent on Growth (Tropic Movements): Directional movements toward or away
from a stimulus.
* Types of Tropic Movements:
- Phototropism: Movement toward light (e.g., shoots bend toward sunlight; positive
phototropism).
- Geotropism: Movement in response to gravity (e.g., roots grow downward into the soil;
positive geotropism).
- Hydrotropism: Movement toward water (e.g., roots growing toward water sources).
- Chemotropism: Movement toward a chemical stimulus (e.g., growth of a pollen tube
toward the ovule during fertilization).
- Thigmotropism: Growth movement in response to touch (e.g., climbing tendrils of pea
plants winding around a support).
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SECTION 4: PLANT HORMONES (PHYTOHORMONES) (PAGE 4)
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* Plant Hormones:
Control and Coordination (Complete Ultra-Detailed Revision Notes)
==================================================
==================================================
SECTION 1: INTRODUCTION & ANIMALS - NERVOUS SYSTEM (PAGE 1)
==================================================
==================================================
* Introduction:
- All living organisms respond and react to various changes or stimuli in their environment
(like light, heat, cold, sound, touch, pressure).
- The working together of various organs in a systematic manner to produce a proper
response to a stimulus is called coordination.
- In animals, this control and coordination are performed by two main systems:
1. Nervous System (Nerves and Brain)
2. Endocrine System (Hormones)
* Receptors:
- Specialized tips of some nerve cells that detect information from the environment. They
are located in our sense organs:
- Phonoreceptors: Inner ear (Hearing and balance of the body)
- Photoreceptors: Eye (Visual stimulus / Sight)
- Olfactory Receptors: Nose (Smell detection)
- Gustatory Receptors: Tongue (Taste detection)
- Thigmoreceptors: Skin (Touch, heat, or cold)
* Neuron (Nerve Cell):
- The structural and functional unit of the nervous system.
- Parts of a Neuron:
1. Dendrite: Acquires the chemical information/stimulus from outside.
2. Cell Body (Cyton): Converts the information into an electrical impulse.
3. Axon: Longest part of a neuron; transmits the electrical impulse from the cell body to
the axon terminal.
- Synapse: The microscopic gap between the axon terminal of one neuron and the
dendrites of the next neuron. Here, the electrical impulse is converted into a chemical signal
(neurotransmitter) to cross the gap.
==================================================
SECTION 2: REFLEX ACTION & THE HUMAN BRAIN (PAGE 2)
==================================================
* Reflex Action:
- A sudden, unconscious, and involuntary response of the body to a dangerous stimulus.
- Example: Pulling back your hand immediately upon touching a hot object.
- Reflex Arc: The pathway taken by nerve impulses in a reflex action.
- Pathway: Stimulus (Hot Object) → Receptor (Skin) → Sensory Neuron → Spinal Cord →
Motor Neuron → Effector Organ (Muscle) → Response (Pulling hand back).
, - Note: Reflex actions are monitored and controlled by the Spinal Cord, not the brain, to
save time and prevent tissue damage.
* The Human Brain:
- The main coordinating center of the body. Protected inside a bony box called the cranium
(skull) and surrounded by cerebrospinal fluid (acts as a shock absorber).
- The brain is divided into three major regions:
1. Fore-brain (Cerebrum): The thinking part. Controls memory, learning, reasoning,
speech, and voluntary actions. It receives sensory impulses from various receptors.
2. Mid-brain: Controls involuntary actions like change in pupil size and reflex movements
of the head, neck, and trunk.
3. Hind-brain: Consists of three main components:
- Cerebellum: Controls posture, body balance, and precision of voluntary actions (e.g.,
walking in a straight line, riding a bicycle).
- Medulla: Controls involuntary actions like blood pressure, salivation, and vomiting.
- Pons: Regulates respiration and breathing cycles.
==================================================
SECTION 3: COORDINATION IN PLANTS (PAGE 3)
==================================================
* Plant Movements:
- Unlike animals, plants do not have a nervous system or muscles. They move and respond
using chemical means.
- Plant movements are of two main types:
1. Independent of Growth (Nastic Movements): Immediate response to a stimulus.
- Example: Drooping of leaves in a 'Touch-Me-Not' plant (Mimosa pudica) upon
touching. This happens due to sudden changes in the amount of water in leaf cells.
2. Dependent on Growth (Tropic Movements): Directional movements toward or away
from a stimulus.
* Types of Tropic Movements:
- Phototropism: Movement toward light (e.g., shoots bend toward sunlight; positive
phototropism).
- Geotropism: Movement in response to gravity (e.g., roots grow downward into the soil;
positive geotropism).
- Hydrotropism: Movement toward water (e.g., roots growing toward water sources).
- Chemotropism: Movement toward a chemical stimulus (e.g., growth of a pollen tube
toward the ovule during fertilization).
- Thigmotropism: Growth movement in response to touch (e.g., climbing tendrils of pea
plants winding around a support).
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SECTION 4: PLANT HORMONES (PHYTOHORMONES) (PAGE 4)
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* Plant Hormones:
