Anatomy And Physiology Of Vestibular Sensation Flashcards
What are the three sources that the sense of equilibrium depends on?
The sense of equilibrium depends on input from the visual system, proprioceptors in muscles and joints, and the vestibular system.
What does the vestibular system include and what information does it provide?
The vestibular system includes the vestibule and semicircular canals within the inner ear. It provides information about head position and movement.
What are the two types of equilibrium detected by the organs in the inner ear?
The inner ear detects two types of equilibrium: static equilibrium, which is maintaining balance when the head is tilted but the head and body are not moving, and dynamic equilibrium, which is maintaining balance when the head or body is undergoing rotational or angular motions or linear acceleration.
What are the utricle and saccule and what do they contain?
The utricle and saccule are segments of the membranous labyrinth in the vestibule. Both contain a macula, which contains receptor cells for head position and movement.
What happens when the stereocilia bend toward and away from the kinocilium?
When the stereocilia bend toward the kinocilium, hair cells depolarize and release more glutamate, which increases the number of action potentials produced in the axons of the vestibular nerve. When the stereocilia bend away from the kinocilium, hair cells hyperpolarize and release less glutamate, which reduces the number of action potentials formed in the axons of the vestibular nerve.
How do the maculae in the utricle and saccule help the brain determine the direction of head tilt?
The maculae are paired so that tilting your head in one direction polarizes hair cells in one ear and hyperpolarizes hair cells in the other ear. This allows the brain to determine which direction the head is tilting.
What is the role of the utricle and saccule in detecting linear acceleration?
The utricle and saccule are involved in detecting linear acceleration, a form of dynamic equilibrium. However, the maculae are sensitive only to changes in the rate of movement, not the movement itself.
How does inertia affect the movement of the otolithic membrane and endolymph in the vestibule?
Inertia causes the endolymph and otolithic membrane in the vestibule to lag behind the movement of the hair cells in the wall of the utricle and saccule. This bending of the stereocilia either increases or decreases neuron activity, which the brain interprets as body acceleration or deceleration.
What are the semicircular ducts and what do they detect?
The semicircular ducts are part of the membranous labyrinth and contain endolymph. They are oriented to detect rotation in all three body planes. Hair cells in the anterior, posterior, and lateral semicircular ducts detect changes in dynamic equilibrium, including angular and rotational movements of the head.
What is the role of the utricle and saccule in detecting linear acceleration?
The utricle and saccule are involved in detecting linear acceleration, a form of dynamic equilibrium. However, the maculae are sensitive only to changes in the rate of movement, not the movement itself.
How does inertia affect the movement of the otolithic membrane and endolymph in the vestibule?
Inertia causes the endolymph and otolithic membrane in the vestibule to lag behind the movement of the hair cells in the wall of the utricle and saccule. This bending of the stereocilia either increases or decreases neuron activity, which the brain interprets as body acceleration or deceleration.
What are the semicircular ducts and what do they detect?
The semicircular ducts are part of the membranous labyrinth and contain endolymph. They are oriented to detect rotation in all three body planes. Hair cells in the anterior, posterior, and lateral semicircular ducts detect changes in dynamic equilibrium, including angular and rotational movements of the head.
How does the brain interpret changes in nerve activity in the semicircular ducts?
When the head starts moving, the brain interprets the change in nerve activity as the beginning of head rotation. When the head stops moving, the opposing movement has the opposite effect on glutamate release and activity of the vestibular nerve, signaling that the head has stopped moving.
What is motion sickness and what causes it?
Motion sickness is a condition characterized by symptoms such as nausea, dizziness, and sometimes vomiting. It occurs during movement, such as riding in a car, boat, or roller coaster, when the brain receives mismatched sensory information from the eyes and the vestibular system.
How can motion sickness be alleviated?
Certain antihistamines or a scopolamine patch can help by relieving nausea. It may also help to sit in the front seat of a car or look at the horizon while on a boat, as this reduces the conflicting information about movement reported by the visual system.
