Lecture Notes: Paired Vestibular End Organs
I. Semicircular Canals as Yoked Pairs
- The three pairs of semicircular canals detect yaw, pitch, and roll rotations.
- The horizontal canals (one on each side) are a yoked pair.
- During head rotation in the yaw plane, one canal gets excited and the other gets inhibited (they cannot be stimulated equally).
- The same principle applies to the anterior and posterior canals (another yoked pair) in the plane of nodding.
II. Alcohol Intoxication and Sensory Mismatch
- Alcohol affects the cupula in the canals, making it lighter and more buoyant.
- The floating cupula can stimulate hair cells in abnormal patterns on both sides.
- This abnormal stimulation creates a signal that doesn’t correspond to real physical movement.
III. Sensory Mismatch Hypothesis and Nausea
- The brain interprets the mismatch in signals from the vestibular system as a sign of ingesting something toxic.
- This triggers nausea and vomiting as a way to expel the potential poison.
IV. Next Steps
- The lecture will discuss the paired otolith organs. Otoconial Masses