How do the hair cells of the crista ampullaris detect rotation of the head?

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1. The crista ampullaris is located in the ampulla of each semicircular canal in the inner ear and is responsible for detecting rotational movements of the head.
2. Each crista ampullaris contains hair cells, which are sensory receptors with hair-like extensions called stereocilia and a single kinocilium.
3. When the head rotates, the endolymph fluid within the semicircular canals lags behind due to inertia, causing it to flow in the opposite direction of the head movement.
4. This fluid movement bends the stereocilia and kinocilium of the hair cells in the crista ampullaris.
5. The bending of these hair cells leads to either depolarization or hyperpolarization, depending on the direction of the bend, which then sends signals to the brain to interpret the direction and speed of the head's rotation.

Key Concepts

Crista Ampullaris

The crista ampullaris is a sensory structure located within the semicircular canals of the inner ear. It contains hair cells that are crucial for detecting angular motion or rotation of the head. When the head rotates, the endolymph fluid within the canals moves, causing the hair cells to bend and generate nerve impulses that inform the brain about the direction and speed of the rotation.

Hair Cells

Hair cells are specialized sensory cells found in the inner ear that play a vital role in the auditory and vestibular systems. They have hair-like projections called stereocilia that respond to mechanical stimuli. In the context of the crista ampullaris, the bending of these stereocilia due to fluid movement leads to the depolarization of the hair cells, resulting in the transmission of signals to the brain regarding head movement.

Vestibular System

The vestibular system is a complex structure in the inner ear responsible for maintaining balance and spatial orientation. It includes the semicircular canals, which detect rotational movements, and the otolith organs, which sense linear accelerations. The information processed by the vestibular system is essential for coordinating balance and eye movements, allowing the body to respond appropriately to changes in position.