Vestibular Physiology Flashcards
What are the two thing the vestibular system senses?
Linear and angular acceleration.
i.e. which way is up? and where am I going?
Otolith organs and semicircular canals
What the morphological difference between vestibular receptor cells and auditory receptor cells?
Auditory cells have no kinocillium
When hair cells bend towards the kinocillium to they hyperpolarize or depolarize?
Depolarize
What is a morphological axis?
Direction of kinocillium. Stereocillia are crosslinked in this direction opening channels, increasing neurotransmitter release and increasing AP generation
What is the structure which all hair cell axises point away from?
Striola
What are the two otolith organs?
Utricle and Saccule
What are the three semicircular canals and in what planes are they located?
Lateral or horizontal (yaw at +30deg pitch)
Posterior (pitch)
Anterior (roll)
What are the components of the ampulla?
Crista (haircell bodies)
Cupula (gelatinous)
Cilia (imbedded in gel)
When you turn your head horizontally to the left which canal hyperpolarizes and which depolarizes?
Left depolarizes increasing firing rate pushing eyes right. Right hyper polarizes
What’s the threshold sensitivity of the SSCs?
2-5 deg/sec or 0.1deg/sec^2
How long does it take the cupula to equalize with endolymph movement?
~30 seconds
This will be the amount of time it takes to illicit a suprathreshold “leans” illusion as well as the time it takes optokinetic nystagmus to build up and vestibular nystagmus to die away
In which direction does nystagmus occur?
Direction of perceived movement
In which direction is nystagmus defined?
Fast phase (saccade)
Where are the vestibular nuclei located?
lateral of the sulcus limitans on the posterior medulla
What is BPPV?
Benign Paroxysmal Positional Vertigo
Loose otolith pushes cupula over causing vertigo in a specific SSC. Otolith usually falls in dependent opening. Posterior canal most common. That causes
