Fitz--hearing

Question 1

Inner ear receptors are divided into two types

Answer 1

Both convert mechanical energy into receptor potentials.

** TYPE I (INNER HAIR CELLS)** are the true sensory receptors that convey information to the brainstem. Afferent innervation

TYPE II (OUTER HAIR CELLS) function as biological amplifiers, essentially acting as motor units. Efferent innervation

Question 2

Depolarization of hair cells is accomplished by what ion?

Answer 2

potassium

Question 3

The __________ detect head rotation (angular acceleration). The ________ detect gravity (linear acceleration). The ___________ is involved in balance and posture, co-ordination of head and body movements and in fixating the visual image on the fovea.

Answer 3

SEMICIRCULAR CANALS

OTOLITH ORGANS (utricle and saccule)

vestibular system

Question 4

Semicircular canals work in pairsSEMICIRCULAR CANALS WORK IN PAIRS (six of them), with depolarization occuring in the SAME direction as the head rotation

(HORIZONTAL CANALS: head left → depolarization left, hyperpolarization right). The natural pairing is of LEFT ANTERIOR with RIGHT POSTERIOR CANAL (and vice versa).

Question 5

nystagmus

normal patient: what do you see?
loss of cortical function: ?
brainstem death: ?

Answer 5

def: rhythmical oscillation of the eyeballs. slow drift of eyes in one direction (pursuit) followed by rapid recovery in opposite direction (succade)

Normal: NYSTAGMUS (PURSUIT [vestibulo-ocular reflex] + SACCADE [higher centers (e.g., cortex)])\

pursuit only

neither pursuit nor saccade

Question 6

Electro-oculogram (EOG)