Chapter 7: Control and Coordination, Class 10, Science
Dear learners , You’ve come so far in your learning journey, and now you’re about to explore one of the most amazing parts of biology – how your body and even plants think, react, and stay in sync. Ever wondered how your hand pulls back the moment you touch something hot, or how sunflowers follow the sun? This chapter will open your eyes to the brilliant coordination happening inside you and in the nature around you – even without you noticing it! So let’s dive in and discover how this hidden system works like magic.
Chapter 7: Control and Coordination – Brief Summary
Imagine your body as a big team. For this team to work smoothly, all the members need to coordinate properly. Like your eyes see a ball coming, your brain understands it, and your hands catch it – all of this happens in just seconds! That’s because your body has a control and coordination system that helps all parts work together.
1. Control and Coordination in Animals
The body has a special type of cell. This is called a sensory nerve cell. Such receptors are found in the sense organs of our body such as the inner ear, nose, tongue, etc. Therefore, the taste buds can taste food and the olfactory buds can smell it.
Nerve cells are made up of cell bodies and nerve processes. There are two types of nerve amplification – axon and dendrite. Dendrites collect nerve messages or stimuli from nearby cells or impulse creates and then through the action to another nerve cell at its end. Some chemicals are released from electrical stimulation in the peripheral branches of the axon. These chemicals are transmitted to another nerve cell through the connecting pathway or synapse between the action of one nerve cell and the dendrites of neighboring cells. This is how nerve impulses are transmitted to our body. Such synapses can also be transmitted to muscle cells or gland cells
Animals have two main systems to control and coordinate their body:
1. Nervous system
2. Hormonal system (endocrine system)
Nervous System – Your Body's Fast Messenger
The nervous system works like a messaging network. It picks up signals from the environment and sends messages to the brain or spinal cord, and then gives instructions to muscles.
Meet the Neuron – The Messenger Cell
A neuron is a special cell that carries messages.
It has 3 parts:
a) Dendrites – Receive messages
b) Cell body – Processes them
c) Axon – Sends messages out to other neurons or body parts
These neurons connect like a chain and pass messages very quickly using electrical signals.
What happens in Reflex Action?
Reflex action is a quick and automatic response of our body to something harmful or sudden, without thinking about it. It helps protect us from danger.
What Happens in Reflex Action:
1. Sense Organs Detect – When you touch something hot or sharp, your skin (sense organ) feels it.
2. Message to Spinal Cord – This message quickly goes to the spinal cord (not the brain).
3. Quick Response – The spinal cord immediately sends a message to the muscles to move.
4. Action Happens – Your hand pulls back quickly even before you feel the pain.
Example: If you accidentally touch a hot pan, your hand moves away very fast. This is a reflex action.
Why It's Important:
Reflex actions protect our body from harm by acting quickly without waiting for the brain to think.
The Human Brain – The Command Center
The human brain is the control center of our body. It helps us think, feel, move, learn, and remember things. It is protected by the skull and is made up of many nerves.
Main Parts of the Brain and Their Actions:
1. Cerebrum:
a) It is the largest part of the brain.
b) Helps in thinking, learning, memory, and decision-making.
c) Controls voluntary actions like walking, writing, or speaking.
2. Cerebellum:
a) Located under the cerebrum.
b) Helps in balancing the body and coordinating movements.
c) Makes movements smooth and steady.
3. Medulla (Brainstem):
a) Connects the brain to the spinal cord.
b) Controls involuntary actions like breathing, heartbeat, and digestion.
c) Works automatically, even when we are sleeping.
Functions of the Brain:
∆ Thinks and solves problems.
∆ Remembers things and stores knowledge.
∆ Controls body movements.
∆ Feels emotions like happiness or anger.
∆ Controls vital body functions like heartbeat and breathing.
Coordination in Plants – Silent But Smart
You might think plants don’t move or react like animals, but they do – just more slowly and differently. They don’t have brains or nerves, but they still respond to touch, light, water, gravity, and chemicals.
Types of Plant Movements:
1. Tropic Movements (Directional, slow):
Phototropism – Movement towards light (e.g., sunflower)
Geotropism – Movement towards gravity (roots growing downward)
Hydrotropism – Movement towards water
Thigmotropism – Response to touch (tendrils wrap around sticks)
2. Nastic Movements (Non-directional, quick):
Example: Touch-me-not plant folds its leaves when touched.
Plant Hormones – The Silent Directors
Plants use chemicals called hormones to control their movements and growth.
Auxins – Help in bending towards light
Gibberellins – Help in stem growth
Cytokinins – Help in cell division
Abscisic acid – Slows down growth; helps during dry seasons
Hormones in Animals – Chemical Messages in the Blood
Apart from the nervous system, animals (including humans) also use hormones to control body functions.
Hormones are chemical messengers made by endocrine glands. They travel in the blood to target organs and control things like growth, sugar level, mood, etc.
Here are some important glands and their hormones:
Endocrine Gland: Hormones are special chemical messengers made by certain glands in our body. These glands are called endocrine glands, and they release hormones directly into the blood. The hormones then travel through the bloodstream to different parts of the body to control and coordinate various functions like growth, metabolism (how our body uses energy), mood, and changes during puberty.
Pituitary Gland: The pituitary gland, also known as the "master gland," produces growth hormone, which helps us grow taller and supports overall body development. The thyroid gland releases a hormone called thyroxine, which controls how fast our body uses energy. If this hormone is too low or too high, it can make us feel tired or overactive.
Adrenal Gland: The adrenal glands produce adrenaline, a hormone that helps us during emergency situations. It increases our heartbeat and breathing rate to prepare us for action – this is called the "fight or flight" response. The pancreas produces a hormone called insulin, which controls the amount of sugar in our blood. If insulin doesn't work properly, it can lead to a disease called diabetes.
Testes and Overies: In boys, the testes produce testosterone, which is responsible for changes during puberty like a deeper voice and facial hair. In girls, the ovaries produce estrogen, which controls the development of female body features during puberty.
Feedback Mechanism – Body’s Self-Control System
Your body is smart. It knows when to start and stop hormone production.
For example:
If sugar level in blood goes up, pancreas releases insulin to bring it down.
Once it’s normal, insulin release stops. This is called a feedback mechanism.
Our body is controlled and coordinated by the nervous system and hormones.
What we learn::
√ The actions of the nervous system can be divided into three categories: reactive actions, voluntary actions and involuntary actions.
√ The nervous system sends electrical impulses to transmit stimuli.
√ The nervous system receives stimuli from our senses and acts through muscles.
√ Chemical combinations are found in both plants and animals.
√ Hormone
s secreted in one part of the body travel to other parts of the body to perform specific functions.
√ Feed-back mechanisms regulate the action of hormones.
Chapter 7: Control and Coordination
Important Questions & Answers (Class 10 – Science)
1. What is coordination in living organisms?
Answer: Coordination is the process by which different parts of the body work together to perform body functions smoothly and respond to changes in the environment.
2. Name the two systems responsible for control and coordination in humans.
Answer: The two systems are the nervous system and the endocrine system (hormonal system).
3. What is a neuron?
Answer: A neuron is a nerve cell that carries messages in the form of electrical impulses. It is the basic unit of the nervous system.
4. Name the three parts of a neuron.
Answer: Dendrites, cell body (cyton), and axon.
5. What is a reflex action? Give one example.
Answer: Reflex action is an automatic and quick response to a stimulus without thinking.
Example: Pulling your hand away from a hot object.
6. Which part of the nervous system controls reflex actions?
Answer: Spinal cord controls reflex actions.
7. What is the function of the brain?
Answer: The brain controls voluntary actions, processes information, stores memory, and coordinates sensory inputs and motor responses.
8. Name the three major parts of the human brain.
Answer: Forebrain, midbrain, and hindbrain.
9. What is the role of the cerebellum (part of the hindbrain)?
Answer: The cerebellum helps in maintaining balance and posture and coordinates body movements.
10. What is phototropism?
Answer: Phototropism is the movement or growth of a plant part in response to light. For example, stems bend towards light.
11. How do plant hormones help in plant growth?
Answer: Plant hormones regulate growth and responses. For example, auxins help in cell elongation, gibberellins in stem growth, and cytokinins in cell division.
12. Name any two plant hormones and their functions.
Answer:
Auxins – Help in bending of stem towards light.
Abscisic acid – Inhibits growth and helps during stress conditions.
13. What is hydrotropism? Give an example.
Answer: Hydrotropism is movement of plant parts towards water.
Example: Roots grow towards a water source.
14. How does the nervous system differ from the hormonal system?
Answer: The nervous system works through electrical impulses and gives a quick response. The hormonal system works through chemical signals and gives a slower but long-lasting effect.
15. What is adrenaline? What is its function?
Answer: Adrenaline is a hormone secreted by the adrenal glands. It prepares the body for emergency situations by increasing heartbeat, breathing, and energy supply.
16. What is the function of insulin?
Answer: Insulin is a hormone produced by the pancreas. It controls blood sugar levels by helping glucose enter cells.
17. What is geotropism? Give an example.
Answer: Geotropism is the movement of plant parts in response to gravity.
Example: Roots growing downward.
18. What is a synapse?
Answer: A synapse is the gap between two neurons where signals pass from one neuron to another using chemicals.
19. What is the feedback mechanism in hormone control?
Answer: Feedback mechanism controls the production of hormones based on the body’s needs. For example, insulin is released when sugar levels are high and stops when levels become normal.
20. Why is the brain called the command center of the body?
Answer: The brain is called the command center because it receives signals from sense organs, processes them, takes decisions, and sends instructions to muscles and glands.
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