Control and Coordination Class 10 Notes | Key Concepts Explained

Master the chapter Control and Coordination with our simplified Class 10 Science notes. This chapter explains how the human body and plants respond to stimuli through the nervous system and hormones. From reflex actions to endocrine glands, every concept is clearly explained. Perfect for CBSE exam preparation and quick revisions. Let’s dive into the world of coordination in living organisms!

The changes in the environment to which the organisms respond and react are called stimuli such as light, heat, cold, smell, touch, etc.

Control and Coordination in Animals

It is done trough two main systems:

ü Nervous System

ü Endocrine System

Nervous System

Nervous System consists of nervous tissue which is made up of an organised network of nerve cells or neurons, and is specialised for conducting information via electrical impulses from one part of the body to another.

Some Key terms associated with Nervous System

Receptors: These are the specialised tips of some nerve cells that detect the information from the environment. These receptors are located in our sense organs.

Neuron: It is the structural and functional unit of nervous system.

A typical neuron consists of following parts:

Parts of a Neuron and Their Functions:

• ✅ Dendrite: These are thin, hair-like branches that come out of the cell body. They receive messages (nerve impulses) from other neurons.
• ✅ Cell body (Cyton): This part looks star-shaped and contains the nucleus and cytoplasm. It processes the signals received and sends them as electrical impulses.
• ✅ Axon: This is the long fiber coming out of the cell body. It carries the electrical impulse away from the cell body and ends in many small branches called axon terminals.
• ✅ Myelin sheath: A protective covering around the axon. It acts like an insulator and helps the signals travel faster.
• ✅ Synapse: This is the gap or junction between the axon terminal of one neuron and the dendrite of the next neuron. Here, the electrical signal changes into a chemical signal to pass to the next neuron.

👉 A special type of synapse between a motor neuron and a muscle fiber is called a neuromuscular junction. (This is often asked in MCQs.)

Dendrites → Cell body → Axon → Nerve endings → Synapse → Dendrite of next neuron
📌 This is an important flow to remember!

Key Words

Voluntary Action: These are actions that we do on purpose and with thinking. They are controlled by our brain.
Examples: Talking to a friend, writing something.

Involuntary Action: These actions happen automatically without us thinking about them. They are not in our control and happen as a quick response to something.
Example: Blinking of eyes, Heartbeat.

Reflex action: It is quick, sudden and immediate response of the body to a stimulus. e.g., Knee jerk, withdrawal of hand on touching hot object.

ü It originates in the spinal cord.

ü In these sensory neurons, spinal cord, relay neuron, motor neuron and effector muscles are involved.

Reflex arc: The pathway through which nerve impulse passes during reflex action is called reflex arc. i.e., it is a pathway through which the reflex action occurs.

✅ A stimulus is first received by sensory neurons.

✅ These sensory neurons carry the message (impulse) to the spinal cord (part of the central nervous system).

✅ The spinal cord understands and processes the message.
✅ Then, motor neurons carry the response (motor impulse) from the spinal cord to the effector organs like muscles to take action.

Human Nervous System

The nervous system of vertebrates (including humans) is divided into the central nervous system (CNS) and the peripheral nervous system (PNS).

Brain

Human brain is the main coordinating centre of the body. It has three major parts: Forebrain, midbrain and hind brain. 

(a) Fore-brain: It is the most complex or specialized part of the brain. It consists of cerebrum. The main functions of forebrain are as follows:

ü Main thinking part of the brain.

ü Controls the voluntary actions.

ü Stores information (memory).

ü Receives sensory impulses from various parts of the body and integrate it.

ü It is the centre associated with hunger. The brain is protected by the skull called the cranium and is surrounded by three membranes called the meninges. [IMPORTANT]

(b) Mid-brain: Controls involuntary actions.

(c) Hind-brain: It has three parts:

ü Cerebellum: Controls posture and balance, precision of voluntary actions. e.g., picking pen.

ü Medulla: Controls involuntary actions. e.g., blood pressure, salivation, vomiting.

ü Pons: Controls voluntary actions and helps in regulation of respiration

Protection of Brain and Spinal Cord

ü Brain is protected by a fluid filled balloon which acts as shock absorber and is enclosed in a bony box.

ü Brain is also protectectd by skull.

ü Spinal Cord is enclosed in vertebral column.

Hormones[Important]

Endocrine System: The endocrine system is made up of special glands called endocrine glands. These glands make chemical messengers called hormones.

Endocrine glands with the hormones names and their secretions in humans are:

Endocrine Gland	Hormone	Function
Hypothalamus	(i) Releasing hormones (RH)	Regulates secretion of pituitary hormones.
Pituitary Gland	(i)Growth Hormone	Controls growth-dwarfism and gigantism.
Thyroid Gland	Thyroxin	Regulate metabolism
Adrenal Gland	Adrenaline	Maintains the blood pressure during stress, happiness, hunger and anxiety
Pancreas	Insulin	Regulate the sugar level in the body
Ovaries	Estrogen	Helps in the development of secondary sexual characters of a female
Testis	Testosterone	Helps in the development of secondary sexual characters of a male
Pineal Gland	Melatonin	Sleep hormone

 

Key Words

(a) Dwarfism: If the body doesn't make enough growth hormone, a person may have dwarfism (very short height).
(b) Gigantism: If too much growth hormone is made, it can lead to gigantism (very tall height).
(c) Goitre: A lack of iodine in the diet can cause goitre (swelling in the neck).
Why iodine is important: The thyroid gland needs iodine to make thyroxin. This hormone helps control how the body uses carbohydrates, fats, and proteins.
(d) Diabetes: When the body doesn't make enough insulin, it can cause diabetes (high blood sugar).

 

Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.

Answer:

Nervous	Hormone
Does not affects the growth	Affects the growth
Electrical impulses travel from one site to other	Chemical hormones reaches the target site
Fast process	Slow process
Nervous tissues are connected to the brain	Endocrine glands secrete these hormones

 

Control and Coordination in Plants

Types of movement in plants

Tropic Movement(Depends on direction): These movement occur due to external stimulus and the direction of movement depends on the stimulus. It affects the growth of plants. It is of four types

(i) Phototropism: Growth movements of plants towards light e.g., shoots bend toward light (positively phototropic) and roots move away from light (negatively phototropic).

(ii) Geotropism: Movement towards gravity. e.g., Roots of a plant are positively geotropic while shoots of a plant are negatively geotropic.

(iii) Chemotropism: Movement towards chemicals. e.g., Growth of pollen tube towards ovule

(iv) Hydrotropism: Movement towards water.

Nastic Movement(Independent of direction): These movement occur due to external stimulus but it's direction of movement does not depend on the direction of stimulus. This is caused due to change in turgor pressure.

E.g. Thigmonasty - Mimosa(touch me not plant)

Photonasty - Sunflower

Plant Hormones

ü These chemical substances control the growth, development and response to stimuli of a plant. These are also known as phytohormones.

Following are the list of plant hormones:

Plant Hormone	Function
Auxin	ü Promotes cell elongation ü Involved in phototropism ü Produced at the shoot tip
Gibberellin	ü Helps to break the seed dormancy ü Elongation of stem and leaf expansion ü Stimulate flowering ü Increase the flower size
Cytokinin	ü Helps in cell division ü Delay leaf aging ü Promotes the growth of chloroplasts ü Opens stomata
Abscisic Acid	ü Closes stomata to reduce lose of water ü Promotes wilting of leaves ü Induces dormancy in seeds and buds
Ethylene	ü Gaseous hormone ü Responds to plant wounding and pathogen attack