Neurons anatomy test 3 lecture

Oct 13, 2024

Nervous Tissue Cells

Overview

  • Two main types of cells in nervous tissue:
    • Neurons
    • Glial Cells
  • Neurons account for ~20% of nervous tissue.
  • Glial cells make up ~80% and support/nourish neurons.

Neurons

  • Main Parts:
    • Dendrites: Extensions that receive signals.
    • Cell Body (Soma): Contains nucleus and organelles.
    • Axon: Sends electrical signals.
  • Central Nervous System (CNS):
    • Bundles of axons = Tracts (myelinated, white matter).
    • Bundles of cell bodies = Nuclei.
  • Peripheral Nervous System (PNS):
    • Bundles of axons = Nerves (may be myelinated or non-myelinated).
    • Bundles of cell bodies = Ganglia.

Neuron Structure

  • Dendrites: Cytoplasmic extensions for receiving information.
  • Cell Body (Soma): Contains organelles (nucleus, mitochondria, etc.).
    • Neurofibrils: Aid in movement and structure.
    • Nissl Bodies: Rough ER that produces proteins, potentially neurotransmitters.
  • Axon Hillock: Cone-shaped area; contains trigger zone for action potentials.
  • Axon: Transmits electrical signals.
    • Can vary in length.
    • Ends in Axon Terminals with synaptic end bulbs for neurotransmitter release.

Myelination

  • Schwann Cells: Produce myelin sheath, insulate axon, aid in impulse transmission.
    • Nodes of Ranvier: Gaps in myelination, facilitate impulse jumping.

Neuron Classifications

  • Functional Classifications:
    • Sensory Neurons: Carry information to CNS.
    • Interneurons: Analytical/processing neurons in CNS.
    • Motor Neurons: Carry information from CNS.
  • Structural Classifications:
    • Multipolar: Many projections; mostly motor neurons.
    • Bipolar: Two projections; found in special senses (e.g., retina).
    • Unipolar: One projection; mainly sensory neurons, fast signal transmission.

Glial Cells

Central Nervous System

  • Total of 4 types (not detailed in this section)

Peripheral Nervous System

  • Total of 2 types (not detailed in this section)

  • Function to support and nourish neurons.

This study guide provides a comprehensive overview of the nervous tissue cells, focusing on their types, structures, functions, and classifications within the CNS and PNS.