Control and Coordination class 10 Notes

Control and Coordination is the process by which different activities of an organism are regulated, adjusted, and organized so that the body works efficiently in response to internal and external stimuli.
In humans, control and coordination are carried out by:

Nervous System
Endocrine System (Hormonal system)

1. Nervous System

Definition:

The nervous system is a control and coordination system that regulates body activities by transmitting electrical impulses rapidly from one part of the body to another.

Functions of Nervous System

Receives information from sense organs
Interprets and processes information
Controls voluntary and involuntary actions
Helps in thinking, memory, learning, and emotions
Maintains coordination among body parts

Neuron – Structural and Functional Unit

What is Neuron?

A neuron is a specialized cell that carries nerve impulses throughout the body.

Structure of Neuron

A neuron consists of three main parts:

1. Dendrites

Short, branched structures
Receive impulses from receptors or other neurons

2. Cell Body (Cyton)

Contains nucleus and cytoplasm
Controls metabolic activities

3. Axon

Long, single fibre
Carries impulses away from cell body
Covered by myelin sheath (insulates axon)

Types of Neurons

Sensory Neuron
- Carries impulses from receptors to CNS
Motor Neuron
- Carries impulses from CNS to muscles or glands
Relay Neuron

Connects sensory and motor neurons in CNS

Transmission of Nerve Impulse

Impulses are electrical in nature
At synapse, impulse is transmitted using chemical substances (neurotransmitters)
Direction of impulse:
Dendrite → Cell body → Axon → Synapse → Next neuron

Reflex Action

What is Reflex Action?

A reflex action is a quick, automatic, involuntary response to a stimulus.

Examples

Pulling hand away from hot object
Blinking of eyes
Sneezing

Reflex Arc

What is Reflex Arc?

The pathway followed by nerve impulse during reflex action is called reflex arc.

Pathway of Reflex Arc

Stimulus → Receptor → Sensory neuron → Spinal cord → Motor neuron → Effector → Response

Note:- Reflex actions are controlled by spinal cord to save time.

Human Nervous System

Divisions of Nervous System

The human nervous system is divided into:

1. Central Nervous System (CNS)

Brain
Spinal cord

2. Peripheral Nervous System (PNS)

Cranial nerves
Spinal nerves

1. Central Nervous System (CNS)

What is Central Nervous System?

The Central Nervous System (CNS) is the main control centre of the body. It receives, processes, and interprets information and sends instructions to different parts of the body.

Components of CNS

The CNS consists of:

Brain
Spinal Cord

Functions of Central Nervous System

Controls voluntary and involuntary actions
Receives sensory information
Coordinates activities of different organs
Controls thinking, learning, memory, and emotions
Maintains body balance and posture

Protection of Central Nervous System

Protection of Brain

Skull (cranium) – hard bony protection
Meninges – three protective membranes
Cerebrospinal Fluid (CSF) – absorbs shocks

Protection of Spinal Cord

Vertebral column (backbone)
Meninges
Cerebrospinal fluid

Brain

What is Brain?

The brain is the most complex organ of the human body and acts as the command centre of the nervous system.

Parts of Brain and Their Functions

The brain is divided into three main parts:

1. Forebrain

Cerebrum

Largest part of the brain
Controls voluntary actions
Centre of intelligence, memory, thinking, learning
Receives sensory impulses from sense organs

Examples of functions:
✔ Writing
✔ Reading
✔ Thinking

2. Midbrain

Connects forebrain and hindbrain
Controls reflex movements of head, neck, and eyes
Associated with vision and hearing

3. Hindbrain

The hindbrain consists of:

a) Cerebellum

Maintains balance and posture
Coordinates muscular activities
Controls precision and accuracy of movements

b) Pons

Regulates breathing
Acts as a bridge between different parts of brain

c) Medulla Oblongata

Controls involuntary actions
Regulates heartbeat, breathing, swallowing, coughing

Spinal Cord

What is Spinal Cord?

The spinal cord is a long, cylindrical structure extending from the medulla oblongata and enclosed within the vertebral column.

Functions of Spinal Cord

Controls reflex actions
Transmits nerve impulses between brain and body
Acts as a connecting link between brain and peripheral nerves

Reflex Action and CNS

Role of CNS in Reflex Action

Reflex actions are controlled by spinal cord
Brain receives information after reflex action is completed
Helps in quick response to harmful stimuli

Difference between Brain and Spinal Cord

Brain	Spinal Cord
Located in skull	Located in vertebral column
Controls voluntary actions	Controls reflex actions
Centre of thinking and memory	Centre for impulse transmission

Important Exam Points

✔ CNS consists of brain and spinal cord
✔ Cerebrum controls voluntary actions
✔ Cerebellum maintains balance
✔ Medulla controls involuntary actions
✔ Spinal cord controls reflex actions

Common Board Questions

Q. Why is the spinal cord important?
Answer: It controls reflex actions and transmits impulses between brain and body.

Q. Name the part of brain that controls involuntary actions.
Answer: Medulla oblongata

2. Peripheral Nervous System (PNS)

What is Peripheral Nervous System?

The Peripheral Nervous System (PNS) consists of all nerves that arise from the brain and spinal cord. It connects the Central Nervous System (CNS) to different parts of the body.
PNS acts as a communication link between CNS and organs.

Components of Peripheral Nervous System

The PNS is made up of:

Cranial Nerves
Spinal Nerves

Functions of Peripheral Nervous System

Transmits sensory impulses from receptors to CNS
Carries motor impulses from CNS to muscles and glands
Helps in voluntary and involuntary activities
Coordinates movement and responses

1. Cranial Nerves

What are Cranial Nerves?

Cranial nerves arise directly from the brain.

Number

12 pairs of cranial nerves

Functions

Supply head, neck, and some internal organs
Control senses like smell, vision, hearing
Control facial movements

Examples

Optic nerve – vision
Olfactory nerve – smell
Auditory nerve – hearing

2. Spinal Nerves

What are Spinal Nerves?

Spinal nerves arise from the spinal cord.

Number

31 pairs of spinal nerves

Functions

Carry impulses to and from spinal cord
Control muscles of trunk and limbs
Involved in reflex actions

Types of Peripheral Nervous System

Based on functions, PNS is divided into:

1. Somatic Nervous System

Controls voluntary actions
Connects CNS to skeletal muscles
Example: Walking, writing

2. Autonomic Nervous System (ANS)

Controls involuntary actions
Regulates internal organs like heart, lungs, stomach

Autonomic Nervous System (ANS)

The ANS is further divided into:

A. Sympathetic Nervous System

Prepares body for emergency situations
Increases heartbeat
Dilates pupils
Reduces digestion

Note: Known as “fight or flight” system

B. Parasympathetic Nervous System

Brings body back to normal state
Decreases heartbeat
Stimulates digestion
Constricts pupils

Note: Known as “rest and digest” system

Difference between Somatic and Autonomic Nervous System

Somatic Nervous System	Autonomic Nervous System
Controls voluntary actions	Controls involuntary actions
Acts on skeletal muscles	Acts on internal organs
Conscious control	Unconscious control

Difference between Sympathetic and Parasympathetic Nervous System

Sympathetic	Parasympathetic
Active in stress	Active in rest
Increases heartbeat	Decreases heartbeat
Dilates pupils	Constricts pupils

Role of PNS in Reflex Action

Sensory nerves carry stimulus to spinal cord
Motor nerves carry response to muscles
Enables quick response without involving brain initially

Important Exam Points

✔ PNS connects CNS with body
✔ Cranial nerves = 12 pairs
✔ Spinal nerves = 31 pairs
✔ ANS controls involuntary actions
✔ Sympathetic = fight or flight

Common Board Questions

Q. What is the function of Peripheral Nervous System?
Answer: It connects CNS to body parts and transmits nerve impulses.

Q. Name the two divisions of Autonomic Nervous System.
Answer: Sympathetic and Parasympathetic nervous system.

2. Endocrine System (Hormonal System)

Definition:

The endocrine system is a system of ductless glands that secrete chemical messengers called hormones directly into the bloodstream to control and coordinate various activities of the body.
Hormonal control is slow but long-lasting.

Functions of Endocrine System

Controls growth and development
Regulates metabolism
Maintains internal balance (homeostasis)
Controls puberty and reproduction
Coordinates activities of different organs

What are Hormones?

Hormones are chemical substances produced in small quantities by endocrine glands and transported through blood to target organs.

Characteristics of Hormones

Secreted in very small amounts
Act on specific target organs
Effects are slow but long-lasting
Regulate body functions

Major Endocrine Glands and Their Hormones

1. Pituitary Gland (Master Gland)

Location

At the base of the brain

Hormone

Growth Hormone (GH)

Functions

Controls growth of bones and muscles
Regulates activities of other endocrine glands

Disorders

Gigantism – excess GH
Dwarfism – deficiency of GH

2. Thyroid Gland

Location

In the neck, in front of trachea

Hormone

Thyroxine

Functions

Regulates metabolism
Controls growth and development
Requires iodine for hormone production

Disorder

Goitre – iodine deficiency

3. Parathyroid Gland

Location

Attached to thyroid gland

Hormone

Parathormone (PTH)

Functions

Regulates calcium and phosphorus levels
Maintains healthy bones and teeth

4. Pancreas

Nature

Both endocrine and exocrine gland

Hormone

Insulin

Functions

Controls blood sugar level
Converts glucose into glycogen

Disorder

Diabetes Mellitus – insulin deficiency

5. Adrenal Gland

Location

Above kidneys

Hormone

Adrenaline

Functions

Prepares body for emergency situations
Increases heartbeat and blood pressure
Known as “fight or flight hormone”

6. Testes (Male)

Hormone

Testosterone

Functions

Development of male secondary sexual characters
Formation of sperms

7. Ovaries (Female)

Hormones

Oestrogen
Progesterone

Functions

Development of female secondary sexual characters
Regulation of menstrual cycle
Maintains pregnancy

Feedback Mechanism

What is Feedback Mechanism?

The feedback mechanism regulates hormone secretion by controlling the amount of hormone released.

Example:
Low thyroxine → pituitary releases more TSH → thyroid releases thyroxine

Difference between Nervous System and Endocrine System

Nervous System	Endocrine System
Electrical impulses	Chemical hormones
Fast response	Slow response
Short-lasting effect	Long-lasting effect
Specific effect	Widespread effect

Importance of Endocrine System

Maintains body balance
Controls growth and puberty
Helps body adapt to stress
Regulates metabolism

Important Exam Points

✔ Hormones are chemical messengers
✔ Endocrine glands are ductless
✔ Pituitary is master gland
✔ Insulin controls blood sugar
✔ Adrenaline is emergency hormone

Common Board Questions

Q. Why is iodine necessary for thyroid gland?
Answer: Iodine is required to produce thyroxine hormone.

Q. Name the hormone responsible for growth.
Answer: Growth hormone (GH)

Coordination in Plants

What is Coordination in Plants?

Coordination in plants refers to the way plants control and regulate their growth, movements, and responses to environmental stimuli using chemical substances called plant hormones (phytohormones).
Plants do not have a nervous system, so coordination is chemical and slow.

Stimuli in Plants

Plants respond to the following stimuli:

Light
Gravity
Water
Touch
Chemicals

These responses help plants survive in changing environments.

Plant Hormones (Phytohormones)

What are Plant Hormones?

Plant hormones are chemical messengers produced in small quantities in plants that control growth, development, and movement.

Types of Plant Hormones and Their Functions

1. Auxins

Promote cell elongation
Help in phototropism
Produced at shoot tips
Cause bending of shoot towards light

Example: Shoot growing towards sunlight

2. Gibberellins

Promote stem elongation
Help in seed germination
Increase fruit size
Break seed dormancy

3. Cytokinins

Promote cell division
Delay ageing of leaves
Help in growth of lateral buds

4. Ethylene

Only gaseous plant hormone
Causes fruit ripening
Promotes falling of leaves and flowers

5. Abscisic Acid (ABA)

Acts as a growth inhibitor
Causes wilting
Induces dormancy
Closes stomata during water stress

Movements in Plants

Plant movements are classified into:

Tropic Movements
Nastic Movements

1. Tropic Movements

What are Tropic Movements?

Tropic movements are directional growth movements of plant parts in response to a stimulus.

Types of Tropism

a) Phototropism (Light)

Shoot grows towards light (positive phototropism)
Root grows away from light (negative phototropism)

b) Geotropism (Gravity)

Root shows positive geotropism
Shoot shows negative geotropism

c) Hydrotropism (Water)

Roots grow towards water source

d) Thigmotropism (Touch)

Tendrils coil around support

2. Nastic Movements

What are Nastic Movements?

Nastic movements are non-directional movements of plant parts in response to stimuli.
They occur due to changes in turgor pressure, not growth.

Examples of Nastic Movements

Folding of leaves in Mimosa pudica (touch-me-not)
Opening and closing of flowers

Difference between Tropic and Nastic Movements

Tropic Movement	Nastic Movement
Directional	Non-directional
Growth-based	Turgor-based
Permanent	Temporary
Slow	Fast

Coordination in Plants vs Animals

Plants	Animals
Chemical coordination	Nervous + hormonal
Slow response	Fast response
No nervous system	Nervous system present

Importance of Coordination in Plants

Helps plants grow towards light and water
Enables plants to respond to environment
Controls flowering, fruiting, and germination

Important Exam Points

✔ Plants use hormones for coordination
✔ Auxin causes phototropism
✔ Ethylene helps in fruit ripening
✔ ABA is growth inhibitor
✔ Tropic movements are directional

Frequently Asked Board Questions

Q. Why do plants show slow responses?
Answer: Because plants use hormones instead of nervous system.

Q. Name the hormone responsible for fruit ripening.
Answer: Ethylene

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