Class 10 – Control and Coordination BEST Science Notes

Class 10 – Control and Coordination
[Pandey Sir’s BEST Classes,
Dammaiguda]
🖊 BEST Science Notes

🧠 Nervous System in Humans

Functions of the Nervous System
It coordinates the activities of the body.
It helps organisms to respond to stimuli (changes in the environment).
Maintains homeostasis (balance within the body).
Parts of the Nervous System

1. Central Nervous System (CNS)
   Brain
   Divided into three parts:
   Forebrain (responsible for intelligence, memory, sensory perception)
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   Midbrain (coordinates movement)
   Hindbrain (controls vital functions like breathing and heart rate)
   Spinal Cord
   It conducts sensory information from the peripheral nervous system to the brain.
   Controls reflex actions.
2. Peripheral Nervous System (PNS)
   Made up of nerves that extend from the brain and spinal cord to all parts of the body.
   Includes somatic nervous system (controls voluntary movements) and autonomic
   nervous system (controls involuntary actions).
3. Neurons
   The basic unit of the nervous system.
   Neurons transmit electrical impulses across the body.
   Consists of dendrites, cell body, axon, and nerve endings.
   

🔄 Coordination in Plants

Plants respond to various stimuli such as light, gravity, touch, etc., but they do not have a
nervous system.
Tropism is the movement of plants in response to stimuli:
Phototropism – movement in response to light.
Geotropism – movement in response to gravity.
Hydrotropism – movement in response to water.
Chemotropism – movement in response to chemicals.
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Plant Hormones
Plants use hormones for control and coordination. The major hormones are:
Auxins: Promote cell elongation, responsible for phototropism.
Gibberellins: Promote stem elongation and seed germination.
Cytokinins: Promote cell division.
Abscisic Acid: Inhibits growth, induces dormancy.
Ethylene: Promotes fruit ripening.
🤖 Reflex Action and Reflex Arc
Reflex Action: An automatic and rapid response to a stimulus without conscious thought.
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Examples: Withdrawing hand from a hot object, blinking when an object comes close
to the eyes.
Reflex Arc: The pathway through which reflex actions occur. It involves:
Receptor: Detects the stimulus.
Sensory Neuron: Carries the signal to the CNS.
Relay Neuron: Processes the signal in the spinal cord.
Motor Neuron: Carries the command from the CNS to the effector.
Effector: Muscle or gland that acts in response.
💉 Endocrine System in Humans
The Endocrine System uses hormones to regulate various functions in the body.
Hormones are chemical messengers secreted directly into the blood by endocrine
glands.
Important Endocrine Glands and Their Hormones
Gland Hormone Function
Pituitary Gland Growth Hormone Regulates growth.
Thyroid Gland Thyroxine Regulates metabolism.
Pancreas Insulin Regulates blood sugar levels.
Adrenal Glands Adrenaline Prepares the body for emergencies (“fight or flight”).
Testes (in males) Testosterone
Controls development of male reproductive system
and traits.
Ovaries (in
females)
Estrogen and
Progesterone
Regulates female reproductive system.
🌱 Coordination in Animals: Nervous and Hormonal Systems
The nervous system provides rapid responses, whereas the hormonal system provides
slower, longer-lasting effects.
Example: Reflex action involves the nervous system, while the regulation of blood sugar
involves hormones (insulin).

🔍 Important Questions

1. What is a reflex action? Explain with an example.
   Answer: A reflex action is an automatic and rapid response to a stimulus without conscious
   thought. For example, pulling your hand away after touching a hot object.
2. What are plant hormones? Name two and their functions.
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   Answer: Plant hormones are chemical substances that regulate growth and development in
   plants. Examples include:
   Auxins: Promote cell elongation and are involved in phototropism.
   Gibberellins: Promote stem elongation and seed germination.
3. How is the brain protected in humans?
   Answer: The brain is protected by the skull, cerebrospinal fluid, and meninges (membranes
   covering the brain).
4. What is the role of the pancreas in the endocrine system?
   Answer: The pancreas secretes insulin, which helps regulate blood sugar levels by allowing
   cells to absorb glucose.
5. Explain the difference between voluntary and involuntary actions.
   Answer:
   Voluntary actions are controlled consciously by the brain, like walking or talking.
   Involuntary actions are automatic and controlled by the autonomic nervous system, like
   heart rate or digestion.
   🌟 Previous Year Questions (PYQs)
6. What is the role of the brain in reflex action?
   Answer: Reflex actions do not involve the brain in initiating a response. Instead, the
   spinal cord handles it. The brain may receive the message after the action has been
   performed.
7. Define ‘tropism’ and explain phototropism.
   Answer: Tropism is the directional movement of plants in response to stimuli.
   Phototropism is the movement of plants toward light.
8. Name the plant hormone that promotes cell division.
   Answer: Cytokinins promote cell division in plants.