Final answer:
Head movement leads to a shift in the otolithic membrane in the utricle and saccule, stimulating hair cells to generate a nerve signal which is processed by the cochlear nucleus and other brain regions for coordination and balance.
Step-by-step explanation:
Steps in Generating Nerve Signal within Macula Utriculi and Sacculi
When the head moves, a series of steps occur to translate that movement into a nerve signal that the brain can interpret. These steps are as follows:
- Tilting of the head causes the otolithic membrane within the utricle and saccule to slide over the macula due to gravity.
- The otoliths on top of otolithic membrane add weight, enhancing the shift of the otolithic membrane which bends the stereocilia of the hair cells.
- Depending on the direction of bending, hair cells undergo depolarization or hyperpolarization, generating a nerve signal.
- The nerve signal is then carried by bipolar neurons from the hair cells to the cochlear nucleus in the medulla.
- From the cochlear nucleus, projections are sent to different parts of the brain including the spinal cord, pons, thalamus, and cerebellum for higher processing.
- These signals result in coordination of movements, feelings of dizziness, motion sickness, and adjustments in vision in relation to body movements.
- Visual signals are integrated in the vestibular system to coordinate eye and head movements.
Coordination of both eyes and head is achieved through networks that involve structures like the superior colliculus and the vestibular system, ensuring that movements are in sync.