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ICSE Class 7 Biology Question 1 of 5

Nervous System in Humans — Question 1

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Question 1

Explain the structure of a nerve cell with the help of a diagram.

Answer

A nerve cell or neuron is the basic structural unit of the nervous system. It has three parts — cell body, axon and dendrites.

  1. The cell body called cyton contains the nucleus.
  2. Many short fibres called dendrons arise from the cell. They further divide to form dendrites. Dendrites receive messages from other neurons.
  3. A single, long fibre called axon extends from the other side of the cell body. It is covered by a sheath called myelin sheath.

Below diagram shows the structure of a neuron:

Explain the structure of a motor nerve cell with the help of a diagram. Nervous System in Humans, Living Science Biology Ratna Sagar Solutions ICSE Class 8.

Chapter 8: Human Body: Nervous System — ICSE Class VII Biology Notes

Comprehensive ICSE Class VII Biology notes on the Human Nervous System covering brain parts (cerebrum, cerebellum, medulla), spinal cord, neuron structure, reflex action, reflex arc, and voluntary vs involuntary actions.

Key Concepts and Topics

Topics covered: Brain, Spinal cord, Neurons, Reflex action, Reflex arc

Weightage: Approximately 8 marks in the exam

Important Points to Remember

  • CNS = brain + spinal cord; PNS = nerves
  • Brain parts: cerebrum (thinking), cerebellum (balance), medulla (involuntary)
  • Neuron: cell body + dendrites (receive) + axon (transmit)
  • Reflex action: automatic response controlled by spinal cord
  • Reflex arc: receptor to sensory nerve to spinal cord to motor nerve to effector
  • Brain protected by skull, meninges, and cerebrospinal fluid
  • Voluntary actions involve brain; reflex actions bypass brain

Frequently Asked Questions

Q: What is a reflex action?

A: A quick, automatic, involuntary response to a stimulus, controlled by the spinal cord without involving the brain.

Q: What are the three main parts of the brain?

A: Cerebrum (thinking), Cerebellum (balance), and Medulla oblongata (involuntary actions).

Q: What is a reflex arc?

A: The pathway of a reflex: Receptor → Sensory nerve → Spinal cord → Motor nerve → Effector.

Exam Preparation Tips

  • Focus on understanding concepts rather than rote memorization
  • Practice drawing and labelling diagrams regularly
  • Use comparison tables for topics that require differentiation
  • Solve previous year questions and practice papers
  • Review the chapter notes provided by Bright Tutorials for comprehensive coverage

For complete chapter notes, practice questions, and test papers, contact Bright Tutorials at 9403781999.