BPK 105 Midterm: Module 5 - Objectives - Part 6
27 Apr 2018
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Module 5 - Objectives - Part 6
● Describe the sense of balance (dynamic and static equilibrium) and how it is
detected by the structures of the inner ear.
- The sense of balance, or equilibrium, has two components: static equilibrium and
dynamic equilibrium.
- Static equilibrium is associated with the vestibule and is involved in evaluating the
position of the head relative to gravity.
-Dynamic equilibrium is associated with the semicircular canals and is involved in
evaluating changes in the direction and rate of head movements.
-Vestibule of the inner ear can be divided into two chambers: the utricle and the
saccule (figure 9.21a
).
- Each chamber contains specialized patches of epithelium called the maculae, which are
surrounded by endolymph.
- maculae, like the spiral organ, contain hair cells.
- tips of the microvilli of these cells are embedded in a gelatinous mass, often called the
otolithic membrane
, weighted by otoliths, particles composed of protein and calcium
carbonate.
- weighted gelatinous mass moves in response to gravity, bending the hair cell microvilli
(figure 9.21c
) and initiating action potentials in the associated neurons.
- action potentials from these neurons are carried by axons of the vestibular portion of the
vestibulocochlear nerve (VIII) to the brain, where they are interpreted as a change in the
position of the head.
- Ex. when a person bends over, the maculae are displaced by gravity, and the resultant
action potentials provide information to the brain concerning the position of the head
(figure 9.22).
- Three semicircular canals are involved in dynamic equilibrium.
- The canals are placed at nearly right angles to one another, enabling a person to detect
movements in essentially any direction.
- base of each semicircular canal is expanded into an ampulla (figure 9.23a
).
- Within each ampulla, the epithelium is specialized to form a crista ampullaris (figure
9.23b).
- Each crista consists of a ridge of epithelium with a curved, gelatinous mass, the cupula,
suspended over the crest.
Document Summary
Describe the sense of balance (dynamic and static equilibrium) and how it is detected by the structures of the inner ear. The sense of balance, or equilibrium, has two components: static equilibrium and dynamic equilibrium. Static equilibrium is associated with the vestibule and is involved in evaluating the position of the head relative to gravity. Dynamic equilibrium is associated with the semicircular canals and is involved in evaluating changes in the direction and rate of head movements. saccule (figure 9. 21 a ). surrounded by endolymph. Vestibule of the inner ear can be divided into two chambers: the utricle and the. Each chamber contains specialized patches of epithelium called the maculae , which are. Ex. when a person bends over, the maculae are displaced by gravity, and the resultant action potentials provide information to the brain concerning the position of the head (figure 9. 22). Three semicircular canals are involved in dynamic equilibrium.
