Special Sense- Equilibrium

Vestibular apparatus

Receptors for equilibrium constitute this

Consists of 3 semicircular ducts

2 chambers (anterior saccule and posterior utricles)

Equilibrium

Divided to

Static equilibrium, dynamic equilibrium

Static equilibrium

Perception of orientation of head in space (tilt in directions)

Detected by saccule and utricle

Dynamic equilibrium

Perception of motion or acceleration

1) linear acceleration, change in velocity in straight line

2) angular acceleration change in rate of rotation

Detected by semicircular ducts

Saccule and Utricle

Each hair cell has 40-70 stereocilia and one true cilium (kinocilium)

Tips of stereocilia and kinocilium are embedded in otolithic membrane

Otolithic membrane is weighted with protein (CaCO3 granules aka otoliths add to inertia of membrane and enhance sense of gravity and motion

Hear erect , otolithic membrane bears directly down on hair cells