Final answer:
The utricles are oriented horizontally with vertically oriented hair cells, while the saccules are oriented vertically with horizontally oriented hair cells. The correct answer is option 2: Horizontally, vertically, vertically, horizontally.
Step-by-step explanation:
The correct answer to the student's question is: Utricles are oriented horizontally, and hair cells are oriented vertically. Saccules are oriented vertically, and hair cells are oriented horizontally. So, the number 2) Horizontally, vertically, vertically, horizontally is the correct option.
The utricle and saccule are vestibular structures in the inner ear that, along with the three semicircular canals, help the human body maintain balance and spatial orientation. They achieve this by detecting linear accelerations and head movements.
The utricle is sensitive to horizontal movements and changes in head position with respect to gravity, while the saccule responds to vertical movements. The hair cells within these structures have stereocilia that project into a viscous gel which, when moved, stimulates the hair cells, allowing the brain to interpret head position and movement.