Neuron Structure and Function

Importance of Neurons

• Neurons likely rank among the top five most interesting cells in the human body.
• Essential for brain and nervous system functions.
• Responsible for thoughts, feelings, and potentially sentience.

Basic Neuron Structure

• Soma (Body):
  • Contains the nucleus.
  • Central part of the neuron.
• Dendrites:
  • Branches off from the soma.
  • Receive signals from other neurons.
• Axon:
  • Long tail extending from the soma, can be very long.
  • Ends at the axon terminal.
• Axon Terminal:
  • Connects to other dendrites or tissues (e.g., muscles).

Additional Components

• Axon Hillock:
  • Junction where the soma connects to the axon.
• Myelin Sheath and Schwann Cells:
  • Insulating cells around the axon.
  • Myelin sheath increases signal transmission efficiency.
• Nodes of Ranvier:
  • Gaps in the myelin sheath.
  • Named after the scientist Ranvier.

Signal Transmission

• Dendrites receive signals, which are summed up and travel to the axon hillock.
• If signals are strong enough, they trigger an action potential along the axon.
• Action potential travels down the axon to the axon terminal.
• Axon terminals connect to dendrites of other neurons or other tissues via synapses.
  • Interaction at synapses can trigger responses in connected neurons or muscles.

Types of Neurons and Triggers

• Signals may originate from various sources:
  • Other neurons' axon terminals (e.g., in the brain).
  • Sensory neurons (e.g., taste buds detecting salt or sugar).
  • Different types of sensors detecting various stimuli.

Key Points

• Neurons are critical for communication within the nervous system.
• Dendrites receive signals, which are processed in the soma and may trigger action potentials along the axon.
• Myelin sheath and nodes of Ranvier enhance signal transmission efficiency.
• Neurons interact via synapses to propagate signals.