Vestibular Function Flashcards
What is the main function of the vestibular system?
To control posture and balance
What is the name for the fluid filled membranous tubes that make up the vestibular system?
Labyrinths
Aside from fluid, what do the labyrinths contain?
Areas of sensory cells responsible for detecting tilt of the head with respect to the body as well as angular acceleration
What are the functions of the areas of sensory cells within the labyrinths?
Detecting head tilt
Detecting angular acceleration
What type of cells are the sensory cells within the labyrinths?
Hair cells, whose cell bodies are embedded in the bone of the skull
What is the name of the fluid found in the labyrinths?
Endolymph
What is the feature of the hair cells and how does the feature differ from normal?
The hair cells have cilia which protrude into the endolymph. Unusually, the cilia have one large kinocilium and sets of progressively smaller stereocilia
What are stereocilia?
The smaller projects of the vestibular cilia that stem from the kinocilium
What is the kinocilium?
The large origin of the cilia on the hair cells from which stems the stereocilia
What is the effect of distortion of the stereocilia in the direction of the kinocilium?
Depolarisation and increased discharge of APs
What is the effect of distorsion of the stereocilia away from the kinocilium?
Hyperpolaristaion and decreased discharge of APs
Which organs within the vestibule detect head tilt?
Macula
Describe the cilia of the macula
They are embedded in a blob of jelly which contains crystals of CaCO3
What is the name for the crystals in which the macular cilia are embedded?
Otoliths
Describe the features of otoliths and concequences of the features
They have a greater density than the endolymph and are therefore affected by gravity. When the head tilts the blob is distorted and shearing forces are exerted on the macular cilia
What is the term form side to side tilting of the head?
Utriculus