Parts of a Neuron

Introduction

• Neurons are individual nerve cells that make up the nervous system.
• Essential for muscle movement, sensing environment, speaking, decision making, and understanding speech.

Dendrites

• Branch-like structures on the neuron.
• Function: Receive messages from other neurons.
• Communication through neurotransmitters (e.g., dopamine, acetylcholine, endorphins).
• Neurotransmitters bind to receptors on dendrites (lock and key mechanism).

Soma (Cell Body)

• Integrates and interprets messages from dendrites.
• Contains the nucleus, which holds the genetic material of the neuron.
• Sustains the life of the neuron.

Axon Hillock

• Located where the soma connects to the axon.
• Generates an electrical charge called an action potential if the incoming signal is strong enough.

Axon

• A long tube-like structure that carries the action potential away from the soma.
• Can range in length from a few millimeters to a few feet.

Myelin Sheath

• Covers the axon, produced by Schwann cells (a type of glial cell).
• Acts as an insulator to protect and speed up the electrical impulse.
• Damage to the myelin sheath (e.g., multiple sclerosis) disrupts communication in the body.
• Types of Axons
  • Myelinated: Usually fast transmission, appears white (white matter in the brain).
  • Unmyelinated: Slower transmission, appears gray (gray matter in the brain).

Nodes of Ranvier

• Small gaps between the myelin sheath on the axon.
• Enable the action potential to 'jump' from node to node, speeding up transmission.

Axon Terminal (Synaptic Buds)

• End of the axon, contains neurotransmitters stored in synaptic vesicles.
• Releases neurotransmitters into the synapse (gap between neurons) to bind to receptors on the next neuron.

Types of Neurons

1. Motor Neuron (Multipolar Neuron)
   • Typical neuron structure.
   • Controls muscle movements (efferent neurons).
2. Sensory Neuron (Unipolar Neuron)
   • Detects environmental information (hot, cold, smell, sight).
3. Interneuron (Bipolar Neuron)
   • Connects motor and sensory neurons.
   • Found in the retina, near ganglion cells.

Summary

• Neurons have roughly the same parts but can look different.
• Essential for fast and efficient communication within the nervous system.