Skip to content
SmartScience
All Biology chapters

ICSE Class 10 · Biology · Chapter 11

The Nervous System

8 topics · 15 questions

Smart summary

Everything you need, in order

Introduction to Nervous System

  • Nervous System: Control and coordination system of body. Responds to stimuli, maintains homeostasis.
  • Components: (1) Central Nervous System (CNS) - brain and spinal cord, (2) Peripheral Nervous System (PNS) - nerves outside CNS.
  • Functions: (1) Receives sensory input, (2) Processes information, (3) Generates responses, (4) Controls voluntary and involuntary actions.
  • Neurons: Basic functional units. Specialized cells that transmit electrical impulses.
  • Nerves: Bundles of axons. Carry impulses between CNS and body parts.
  • Diagram Importance: Overview diagram of human nervous system showing CNS and PNS is essential.

Neuron - Structure and Function

  • Neuron: Structural and functional unit of nervous system. Specialized for impulse transmission.
  • Parts: (1) Dendrites - receive impulses, (2) Cell body (cyton) - contains nucleus, (3) Axon - conducts impulses away, (4) Axon terminals - pass impulses to next neuron, (5) Myelin sheath - insulating layer, speeds conduction.
  • Types: (1) Sensory neurons - carry impulses from receptors to CNS, (2) Motor neurons - carry impulses from CNS to effectors, (3) Interneurons - connect neurons within CNS.
  • Synapse: Junction between two neurons. Impulse transmission via neurotransmitters (acetylcholine).
  • Impulse Transmission: Electrical (along neuron) and chemical (across synapse).
  • Diagram Importance: Detailed labeled diagram of neuron showing all parts is crucial for ICSE.

Central Nervous System - Brain

  • Brain: Control center. Located in cranium. Weight: 1.3-1.4 kg.
  • Parts: (1) Cerebrum (largest part) - controls voluntary actions, intelligence, memory, (2) Cerebellum - maintains balance and coordination, (3) Medulla oblongata - controls involuntary actions (breathing, heartbeat).
  • Protection: (1) Cranium (skull), (2) Meninges (membranes), (3) Cerebrospinal fluid (CSF) - shock absorber.
  • Functions: Cerebrum - thinking, learning; Cerebellum - posture, balance; Medulla - vital functions.
  • Diagram Importance: Labeled diagram of human brain showing cerebrum, cerebellum, medulla is frequently asked.

Central Nervous System - Spinal Cord

  • Spinal Cord: Cylindrical structure. Extends from medulla to lumbar region. Length: 45 cm.
  • Structure: (1) Grey matter (inner) - neuron cell bodies, (2) White matter (outer) - myelinated axons, (3) Central canal - contains CSF.
  • Functions: (1) Reflex actions, (2) Conducts impulses between brain and body, (3) Controls simple movements.
  • Protection: Vertebral column, meninges, CSF.
  • Diagram Importance: Cross-section of spinal cord showing grey and white matter is important.

Peripheral Nervous System

  • Peripheral Nervous System: Nerves outside CNS. Connects CNS to body parts.
  • Cranial Nerves: 12 pairs. Originate from brain. Example: Optic nerve (vision), Auditory nerve (hearing).
  • Spinal Nerves: 31 pairs. Originate from spinal cord. Mixed nerves (sensory and motor).
  • Somatic Nervous System: Controls voluntary actions (skeletal muscles).
  • Autonomic Nervous System: Controls involuntary actions (smooth muscles, glands). Divisions: Sympathetic (fight or flight), Parasympathetic (rest and digest).
  • Difference: Somatic - voluntary, conscious; Autonomic - involuntary, subconscious.

Reflex Action

  • Reflex Action: Automatic, rapid response to stimulus. Protects body from harm.
  • Reflex Arc: Pathway of impulse. Receptor → Sensory neuron → CNS → Motor neuron → Effector.
  • Components: (1) Receptor - detects stimulus, (2) Sensory neuron - carries impulse to CNS, (3) Interneuron - processes in CNS, (4) Motor neuron - carries impulse to effector, (5) Effector - muscle or gland that responds.
  • Types: Simple reflex (knee jerk), Conditioned reflex (salivation at bell).
  • Importance: Quick response without conscious thought. Saves time and energy.
  • Diagram Importance: Diagram of reflex arc showing all components and direction of impulse is crucial.

Coordination in Nervous System

  • Coordination: Integration of sensory input and motor output.
  • Nervous Coordination: Fast, short-term. Uses electrical impulses.
  • Chemical Coordination: Slower, long-term. Uses hormones (endocrine system).
  • Integration: Brain integrates information from various senses to produce coordinated response.
  • Feedback Mechanism: Response modifies stimulus. Example: Body temperature regulation.

Diseases and Disorders

  • Meningitis: Inflammation of meninges. Causes: viral or bacterial infection. Symptoms: headache, fever, stiff neck.
  • Polio: Viral infection affecting motor neurons. Causes paralysis. Prevented by vaccination.
  • Alzheimer's Disease: Degeneration of brain cells. Causes memory loss, dementia.
  • Parkinson's Disease: Degeneration of dopamine-producing neurons. Causes tremors, rigidity.
  • Epilepsy: Abnormal electrical activity in brain. Causes seizures.
  • Stroke: Interruption of blood supply to brain. Causes paralysis or death.
  • Prevention: Healthy lifestyle, vaccination, avoid head injuries, regular exercise.

Quiz

Test your knowledge

Multiple choice

  1. Question 1 of 15Knowledge
    The basic functional unit of nervous system is:
  2. Question 2 of 15Knowledge
    The part of neuron that receives impulses is:
  3. Question 3 of 15Knowledge
    The largest part of human brain is:
  4. Question 4 of 15Knowledge
    The reflex action is controlled by:
  5. Question 5 of 15Knowledge
    The insulating layer around axon is:
  6. Question 6 of 15Knowledge
    Synapse is the junction between:
  7. Question 7 of 15Knowledge
    The autonomic nervous system controls:
  8. Question 8 of 15Comprehension
    The cerebellum is responsible for:
  9. Question 9 of 15Assertion-Reasoning
    Assertion (A): Reflex actions are faster than voluntary actions. Reason (R): Reflex actions do not involve brain.
  10. Question 10 of 15Knowledge
    The neurotransmitter at neuromuscular junction is:
  11. Question 11 of 15Knowledge
    The spinal cord is protected by:
  12. Question 12 of 15Knowledge
    The part of brain that controls involuntary actions is:
  13. Question 13 of 15Knowledge
    The gap between two neurons is called:
  14. Question 14 of 15Knowledge
    Which part of neuron contains nucleus?
  15. Question 15 of 15Application
    The disease caused by degeneration of dopamine neurons is:

0 of 15 answered