Scenario 27

Question 1

What does balance receive inputs from?

Answer 1

Vestibular system, proprioception and vision

Question 2

Where is the vestibular apparatus located?

Answer 2

Petrous part of the temporal bone

Question 3

What does the bony labyrinth consist of?

Answer 3

Ant, lat and post semicircular canal, ampulla, fenestra cochleae (round window) or vestibuli (oval window), canal for facial nerve and cochlea

Question 4

What does the membranous laryrinth consist of?

Answer 4

Utricle containing endolymph (high K low Na), surrounded by perilymph (high Na low K)

Question 5

How do hair cells work?

Answer 5

Tallest hair is kinocilium with shorter following in a staircase creating the axis of polarity connected by tip links joining the hair to the upper layer. When the links are stretched the ion channels open and K travel into the cell from endolymph down concentration gradient. Depolarises the cell and Ca flows in causing NT release

Question 6

What happens if hairs are bent the other way?

Answer 6

Hyperpolarisation and decreased firing (bend towards shortest hair)