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Understanding Neuron Structure and Function

May 2, 2025

Biology Lecture Notes: Reception, Response, and Coordination in Animals

Overview

  • Topic: Structure and function of nerve cells (neurons)
  • Previous Lesson Recap:
    • Irritability in animals
    • Nervous system
    • Endocrine system

Nerve Cells (Neurons)

  • Definition: Basic unit of the nervous system, specialized for transmission of nerve impulses (electrical in nature).
  • Function: Transmit electrical messages (impulses) within the nervous system.

Structure of a Neuron

  • Cell Body:

    • Contains the nucleus, which holds genetic material.
    • Equivalent to a typical cell structure.
  • Dendrites:

    • Extensions from the cell body that receive and transmit nerve impulses to adjacent nerve cells.
  • Axon:

    • Main projection from the cell body, essential for conducting impulses.
    • Contains axoplasm, equivalent to cytoplasm in cells.
  • Myelin Sheath:

    • Fatty layer surrounding the axon.
    • Insulates the axon and aids in the propagation of nerve impulses.
  • Schwann Cell:

    • Secretes the myelin sheath.
    • Contains a membrane called the neurilemma.
  • Terminal Dendrites:

    • Located at the end of the neuron, involved in transmitting signals.

Special Features

  • Node of Ranvier:
    • Gaps in the myelin sheath that speed up nerve impulse transmission.

Assignment Questions

  1. Name the basic unit of a nervous system.
  2. Draw a well-labeled diagram of a neuron.
  3. Explain the roles of the following:
    • Myelin Sheath
    • Nodes of Ranvier

Conclusion

  • The nerve cell is essential for transmitting electrical impulses, similar to how current flows through a wire.
  • Understanding the structure and function of neurons is fundamental for studying the nervous system.