Lecture on the Vestibular and Auditory System

Introduction to Senses

• Commonly recognized senses: sight, sound, taste
• Lesser-known sense: vestibular system
  • Important for balance and spatial orientation
  • Involves receptors in inner ear, crucial for sense of balance

The Inner Ear and Vestibular System

• Focus on the auditory system, specifically the inner ear
• Key structures:
  • Cochlea: Processes sound, transfers information to the brain
  • Semicircular Canals:
    • Anterior, posterior, and lateral (horizontal) canals
    • Orthogonal (right-angle) arrangement
    • Lined with a fluid called endolymph, detecting head rotation

Understanding the Semicircular Canals

• Spatial orientation using axes:
  • X-axis: nose to back of the head
  • Y-axis: left ear to right ear
  • Z-axis: straight up and down
• Function:
  • Rotations cause endolymph to shift
  • Detects head rotation plane and strength of rotation

Otolithic Organs

• Components: utricle and saccule
• Detect linear acceleration and head positioning
• Contains calcium carbonate crystals attached to hair cells within a gel
  • Movement (e.g., standing to lying) shifts crystals
  • Pulls on hair cells, triggering action potentials to the brain

Fascinating Facts

• Crystals in ear react to gravity and acceleration
• Allow detection of head positioning
• Malfunctions cause dizziness and vertigo

Dizziness and the Vestibular System

• Continued movement of endolymph after spinning causes dizziness
• Can combat dizziness by spinning in the opposite direction

Gravity and Disorientation

• Absence of gravity (e.g., astronauts) affects otolithic organs
• Scuba diving disorientation due to buoyancy affecting gravity perception
• Lack of visual cues can exacerbate disorientation

Conclusion

• Vestibular system crucial for balance, affected by various factors
• Understanding helps in managing dizziness and disorientation