Class 10 Science Notes Chapter 6 ‘Control and Coordination’: Important Concepts and Guide

How do you react instantly after touching a hot object, and why do plants naturally grow towards sunlight? Both are examples of control and coordination, which enable living organisms to sense changes in their surroundings and produce suitable responses. 

Class 10 science notes Chapter 6 control and coordination, explores how animals use the nervous and endocrine (hormonal) systems to detect and respond to stimuli, and how plants, which lack nerves and muscles, achieve the same goal using hormones and changes in cell water content.

This class 10 science notes chapter 6 control and coordination builds on the idea that all living organisms must recognise events in their environment and respond appropriately. Understanding human physiology and plant biology in higher studies and competitive exams like NEET.

Topics Covered in Class 10 Science Notes Chapter 6 Control and Coordination 

Control and Coordination	Coordination in Plants
Control and Coordination in Animals: The Nervous System	Movement Due to Growth (Tropisms)
How Information Is Detected Through Senses	Plant Hormones
Structure and Function of a Neuron	Hormones in Animals: The Endocrine System
Reflex Actions and the Reflex Arc	Adrenaline
The Human Brain	Major Endocrine Glands and Hormones
Protection of the Nervous System	Feedback Mechanism

Class 10 Science Notes Chapter 6 Control and Coordination Notes

Movement in living things is not always a sign of life through growth alone. Some movements, such as a cat running or a swing being pushed, have nothing to do with growth. 

Since multicellular organisms have specialised tissues for every major function, they also have specialised tissues for control and coordination, namely the nervous and hormonal systems. 

Control and Coordination in Animals: The Nervous System

The nervous system is the primary control system in animals, enabling them to detect changes in their surroundings and respond quickly. It works through a network of specialised nerve cells called neurons, which transmit electrical impulses between different parts of the body. 

How Information Is Detected Through Senses

Before the body can respond to any change in its surroundings, it must first detect the stimulus. This is made possible by specialised receptor cells present in different sense organs. 

Some common receptors include:

• Eyes: Detect light and help us see.
• Ears: Detect sound and help maintain balance.
• Nose: Contain olfactory receptors that detect smell.
• Tongue: Contains gustatory receptors that detect taste.
• Skin: Detects touch, pressure, temperature, and pain.

Structure and Function of a Neuron 

Once a stimulus has been detected by the receptors, the information must be transmitted to the brain, spinal cord, or other parts of the body. The transmission of a nerve impulse takes place in the following steps:

• A stimulus detected at the dendritic tip of a neuron triggers a chemical change that generates an electrical impulse.
• The impulse travels from the dendrites to the cell body and then along the axon.
• At the end of the axon, the impulse causes the release of chemical messengers.
• These chemicals cross a tiny gap called the synapse and stimulate the next neuron, muscle, or gland to generate a new electrical impulse.
• This continuous transmission of impulses enables information to travel quickly throughout the nervous system, allowing the body to produce an appropriate response

Reflex Actions and the Reflex Arc 

In situations where an immediate reaction is needed to prevent injury, the body responds automatically through a mechanism known as a reflex action. 

A reflex action works as follows:

• It is a rapid and automatic response to a stimulus, such as pulling your hand away after touching a hot object.
• Instead of waiting for the brain to process the information, the body uses a reflex arc, a direct pathway that produces a quick response.

A reflex arc connects a sensory (input) neuron to a motor (output) neuron, usually through the spinal cord.

• The motor neuron immediately carries the signal to the muscles, causing them to respond without conscious thought.
• At the same time, the information is also sent to the brain, allowing you to become aware of the stimulus after the reflex action has already taken place.

The Human Brain 

The brain and spinal cord together form the central nervous system (CNS), while the peripheral nervous system (cranial and spinal nerves) connects the CNS to the rest of the body. 

The brain has three main parts:

Part of Brain	Main Functions
Fore-brain	Main thinking region; processes sensory information (sight, hearing, smell); controls voluntary actions and houses centres for hunger, etc.
Mid-brain and Hind-brain (Medulla)	Control involuntary actions like blood pressure, salivation, and vomiting
Hind-brain (Cerebellum)	Maintains posture and balance; ensures precision of voluntary movements

Protection of the Nervous System 

The brain and spinal cord are the main control centres of the body and are responsible for coordinating almost every activity. The nervous system is protected in the following ways:

• The brain is enclosed within the skull, a strong bony structure that protects it from external damage.
• It is also surrounded by a fluid-filled membrane that acts as a cushion and absorbs shocks during sudden movements or impacts.
• The spinal cord is protected by the vertebral column (backbone), which shields it while allowing flexibility and movement.

How Nervous Tissue Produces Movement 

Detecting a stimulus and sending a nerve impulse is only part of the response. To complete the action, the signal must reach the muscles, where it is converted into movement. 

The process of producing movement occurs as follows:

• An electrical impulse travels through a motor neuron and reaches the muscle.
• The impulse causes special proteins inside the muscle cells to change their shape and arrangement.
• As these proteins slide past one another, the muscle fibres contract and shorten.
• This contraction produces movement in the required part of the body.
• In this way, nervous signals are converted into physical movement, allowing the body to respond effectively to different stimuli.

Coordination in Plants

Plants have no nervous system or muscles, yet they respond to stimuli using electro-chemical signals and changes in cell water content rather than specialised conducting tissue or contractile proteins.

The "touch-me-not" (Mimosa/chhui-mui) plant folds its leaves rapidly when touched. This movement does not involve growth; instead, cells change shape by gaining or losing water, causing swelling or shrinking.

Movement Due to Growth (Tropisms) 

Some plant movements occur through directional growth and are therefore slower:

• Phototropism grows in response to light; shoots bend towards light, roots bend away from it.
• Geotropism grows in response to gravity; roots grow downward, shoots grow upward.
• Hydrotropism grows in response to water.
• Chemotropism grows in response to chemicals, such as the growth of pollen tubes towards ovules.

In pea plant tendrils, the side in contact with a support grows more slowly than the side away from it, causing the tendril to coil around the support.

Plant Hormones 

Plant hormones are chemical substances synthesised at one location in the plant and transported to another location where they act.

Hormone	Main Function
Auxin	Promotes cell elongation; causes bending of shoots towards light
Gibberellins	Promote stem growth
Cytokinins	Promote cell division; concentrated in fruits and seeds
Abscisic acid	Inhibits growth; causes wilting of leaves

Hormones in Animals: The Endocrine System

Chemical coordination in animals occurs through hormones secreted by endocrine glands directly into the blood, allowing signals to reach all cells of the body rather than only nerve-connected ones.

Adrenaline 

Secreted by the adrenal glands during stressful or scary situations, adrenaline increases heart rate (more oxygen to muscles), redirects blood away from digestion and skin towards skeletal muscles, and increases breathing rate preparing the body for a "fight or flight" response.

Major Endocrine Glands and Hormones

Hormone	Gland	Function
Growth hormone	Pituitary gland	Stimulates growth in all body organs; deficiency in childhood causes dwarfism
Thyroxin	Thyroid gland	Regulates carbohydrate, protein, and fat metabolism; requires iodine; deficiency causes goitre
Insulin	Pancreas	Regulates blood sugar levels; deficiency leads to diabetes
Testosterone	Testes	Brings about changes during puberty in males
Oestrogen	Ovaries	Development of female sex organs; regulates the menstrual cycle
Releasing hormones	Hypothalamus	Stimulate the pituitary gland to release its hormones

Feedback Mechanism 

Hormone secretion is regulated by feedback loops. For example, when blood sugar rises, the pancreas releases more insulin; as blood sugar falls, insulin secretion decreases, keeping hormone levels balanced according to the body's needs.