Lecture on Parts of a Neuron

Introduction

• Neurons are individual nerve cells comprising the nervous system.
• They enable information travel throughout the body.
• Essential for functions like muscle movement, sensory detection, speech, decision-making, and comprehension.

Key Structures of a Neuron

Dendrites

• Small branches similar to fingers.
• Function: Receive messages from other neurons.
• Communication: Done through neurotransmitters (chemical messages).
• Examples of Neurotransmitters:
  • Dopamine: Related to reward and pleasure.
  • Acetylcholine: Controls muscles.
  • Endorphins: Act as pain relievers.

Soma (Cell Body)

• Contains the nucleus (genetic material).
• Integrates and interprets chemical messages received by dendrites.

Axon Hillock

• Connects the soma to the axon.
• Importance: Initiates the electrical charge (action potential) if the signal is strong enough.

Axon

• Long tube extending from the neuron.
• Carries the electrical signal (action potential).
• Can vary in length from millimeters to several feet.
• Myelin Sheath:
  • Insulates and speeds up the impulse.
  • Made by glial cells or Schwann cells.
  • Disease: Multiple sclerosis disrupts myelin, affecting signal transmission.

Types of Axons

• Myelinated: Faster signal transmission.
• Unmyelinated: Slower signal transmission.
• Color and Brain Matter:
  • White matter: Made of myelinated axons, appears white.
  • Gray matter: Made of unmyelinated neurons, appears gray.

Nodes of Ranvier

• Small gaps in the myelin sheath.
• Facilitate action potential to "bounce" from node to node, increasing speed.

Axon Terminal

• Terminal branches at the end of the axon.
• Synaptic Vesicles: Store neurotransmitters.
• Releases neurotransmitters into the synapse to bind with the next neuron's receptors.

Types of Neurons

• Motor Neuron (Multipolar Neuron)
  • Typical neuron structure.
  • Assist in muscle movement.
• Sensory Neuron (Unipolar Neuron)
  • Detect environmental information like temperature and smell.
• Interneuron (Bipolar Neuron)
  • Connect motor and sensory neurons.
  • Found in the retina, near ganglion cells.

Conclusion

• Neurons have essential parts with various functions.
• Though parts are similar, neuron structures can vary significantly.
• Understanding these components helps clarify neuron function and communication.