Class 10 Science – Chapter 7: Control and Coordination Full NCERT Notes 

Human life is a complex symphony of movements, thoughts, and reactions — yet every action, from blinking our eyes to running fast, is beautifully organized by a system called control and coordination. This system ensures that all parts of our body work together in harmony, responding properly to the environment around us.

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🌱 Introduction to Control and Coordination

Every organism — from a tiny amoeba to a human being — must respond to its surroundings.

• Plants respond by bending towards light or roots growing toward water.

• Animals respond through nerves and hormones.

Control and Coordination is the process that ensures all organs of the body work together efficiently.

It is mainly controlled by:

1. The Nervous System (using electrical impulses)

2. The Endocrine System (using hormones)

Both systems work hand in hand to maintain balance or homeostasis in our body.

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⚡ The Nervous System

The nervous system is a network of special cells called neurons that carry messages throughout the body. It helps detect changes in the environment and makes the body react accordingly.

🧩 Structure of a Neuron

A neuron is the structural and functional unit of the nervous system.
It has three main parts:

• Cell body (cyton): Contains the nucleus and cytoplasm.

• Dendrites: Short, branched extensions that receive signals.

• Axon: A long fiber that carries the message away from the cell body to other neurons or muscles.

Messages travel as electrical impulses through the neuron and are transmitted between neurons by neurotransmitters.

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⚙️ Types of Neurons

1. Sensory Neurons – Carry messages from sense organs to the brain/spinal cord.

2. Motor Neurons – Carry commands from brain/spinal cord to muscles or glands.

3. Relay (Inter) Neurons – Connect sensory and motor neurons inside the central nervous system.

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🧬 Transmission of Nerve Impulse

1. The dendrite of a neuron receives information from the environment or another neuron.

2. This information is converted into an electrical impulse.

3. The impulse passes through the axon to the axon terminal.

4. Here, it triggers the release of neurotransmitters.

5. These chemicals cross the small gap between two neurons — called a synapse — to continue the message.

This rapid transmission allows us to respond within milliseconds to any stimulus.

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🧠 Human Nervous System

The human nervous system is divided into three parts:

1. Central Nervous System (CNS) – Brain and Spinal Cord.

2. Peripheral Nervous System (PNS) – Nerves from the brain and spinal cord to the rest of the body.

3. Autonomic Nervous System (ANS) – Controls involuntary actions like heartbeat and digestion.

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🧠 The Brain

The brain is the control center of the body — it receives information, interprets it, and sends commands.

It is protected by:

• The skull (cranium),

• Cerebrospinal fluid, which acts as a shock absorber, and

• Three layers of membranes called meninges.

The brain is divided into three main parts:

1. Forebrain

• Cerebrum: Largest part; controls intelligence, memory, emotions, speech, and voluntary actions.

• Thalamus: Relays sensory information.

• Hypothalamus: Regulates hunger, thirst, temperature, and connects to the endocrine system.

2. Midbrain

Controls reflex movements of eyes and head.

3. Hindbrain

• Cerebellum: Maintains balance and posture.

• Pons: Helps in breathing control.

• Medulla oblongata: Controls involuntary activities like heartbeat and breathing.

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⚙️ Reflex Action

Sometimes the body reacts instantly without the brain’s direct involvement — for example, pulling your hand back from a hot object.
This automatic and rapid response is called a reflex action.

Reflex actions are controlled by the spinal cord, not the brain.

Reflex Arc Pathway:

Stimulus → Receptor → Sensory Neuron → Spinal Cord → Motor Neuron → Effector → Response

Example: Touching a hot object → Skin receptors → Spinal cord → Muscles contract → Hand withdraws.

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🌿 Coordination in Plants

Unlike animals, plants do not have a nervous system.
Yet, they respond to stimuli like light, gravity, water, and touch using hormones.

🌻 Types of Plant Movements

1. Tropic Movements – Directional movements towards or away from a stimulus.

   • Phototropism: Movement towards light (e.g., shoot bends toward light).

   • Geotropism: Movement in response to gravity (roots downward).

   • Hydrotropism: Response to water (roots grow toward moisture).

   • Thigmotropism: Response to touch (e.g., pea tendrils winding).

   • Chemotropism: Growth due to chemicals (e.g., pollen tube towards ovule).

2. Nastic Movements – Non-directional, caused by changes in internal water pressure.

   • Example: Touch-me-not (Mimosa pudica) folds its leaves when touched.

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🌾 Plant Hormones

Plants coordinate growth and responses using chemical messengers called phytohormones.

Hormone	Function
Auxins	Promote cell elongation; responsible for phototropism and root growth.
Gibberellins	Stimulate stem growth, seed germination, and fruit development.
Cytokinins	Promote cell division and delay leaf aging.
Abscisic Acid (ABA)	Inhibits growth; causes dormancy and leaf fall (stress hormone).

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🧍‍♂️ Coordination in Humans (Hormonal System)

When nerve impulses cannot control long-term processes like growth or metabolism, the endocrine system takes over.
It uses hormones — chemical messengers secreted by glands — transported through blood.

🧩 Endocrine Glands and Their Functions

Gland	Hormone	Function
Pituitary	Growth hormone, TSH, FSH	Controls other glands, body growth.
Thyroid	Thyroxine	Controls metabolism and energy.
Parathyroid	Parathormone	Regulates calcium and phosphorus levels.
Adrenal	Adrenaline	Prepares body for emergency (fight or flight).
Pancreas	Insulin, Glucagon	Controls blood sugar level.
Testes	Testosterone	Male secondary sexual characteristics.
Ovaries	Estrogen, Progesterone	Female secondary sexual characteristics.
Pineal	Melatonin	Controls sleep cycle.

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⚖️ Feedback Mechanism

The endocrine system maintains balance using feedback loops.
For example:

• If blood sugar rises → pancreas releases insulin → cells absorb sugar → sugar levels drop → insulin secretion stops.

• This keeps the body’s internal environment stable (homeostasis).

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🧩 Coordination Between Nervous and Hormonal Systems

Both systems complement each other:

• The hypothalamus (in the brain) controls the pituitary gland (master gland).

• The pituitary then regulates other glands like the thyroid, adrenals, and gonads.
  Thus, the body maintains smooth coordination between thoughts, actions, and internal processes.

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⚡ Disorders Related to Control and Coordination

• Goitre: Caused by iodine deficiency → enlarged thyroid gland.

• Diabetes: Caused by insulin deficiency → high blood sugar.

• Dwarfism/Gigantism: Due to abnormal secretion of growth hormone.

• Epilepsy: Sudden, uncontrolled brain activity causing seizures.

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🧭 Summary

• Control and Coordination is essential for maintaining harmony in the body.

• Nervous system handles fast actions; endocrine system manages slow, long-term changes.

• Brain controls voluntary activities, while reflexes are handled by the spinal cord.

• Plants coordinate through hormones and show tropic and nastic movements.

• Feedback mechanisms ensure stability within the body.

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💡 Interesting Facts

• The brain uses 20% of the body’s total energy.

• The length of all nerves in the human body combined is over 45 miles!

• There are more connections in one brain than stars in the Milky Way galaxy.

• Plants can “communicate” chemically — warning nearby plants of danger like insect attacks.