3.3 Accelerated Motion and Life
39
Fig. 3.2 Tolerance to high
g’s. Not shown is brain
trauma and tissue tearing for
accelerations above 50 g
Fig. 3.3 Right inner ear
Semicircular
Canals
Cochlea
(Utricle)
(Saccule)
Oval Window
Round Window
When the body undergoes acceleration, particularly when the acceleration is
rapidly changing in magnitude and or direction, the brain can quickly get confusing
signals from the inner ear, from muscle and joint proprioceptors, and from the eyes.
Often, dizziness, disorientation, nausea and vertigo result. Experience, training, and
mental attitude can be effective in reducing or even eliminating these effects.
To help us keep balance and orientation, and to help keep our eyes focused at one
place even while your head moves, each inner ear has a vestibular system of three
semicircular canals nearly at right angles (Fig. 3.3), holding a fluid (the endolymph),
and two other organs, called otoliths, the utricle and the vestibule. The semicircular
canals have nerve hairs cells which sense when endolymph fluid shifts when your
head rotates. The otoliths sense the direction of gravity and linear acceleration. They
contain tiny calcium stones (otoconia) which can move within a gel, and nerve hair
cells to detect this movement. The action of the gel on the otoconia is analogous to
the action of the springs on the mass shown in the Fig. 3.4. Within the linear elastic
range of the springs, the greater the acceleration, the greater the displacement of
the mass. Measuring this displacement is a measure of the acceleration, which can
be calibrated in g’s. Displacement of nerve hair cells in the gel in the utricle and
saccule of our inner ear sends linear acceleration information to the brain.
39
Fig. 3.2 Tolerance to high
g’s. Not shown is brain
trauma and tissue tearing for
accelerations above 50 g
Fig. 3.3 Right inner ear
Semicircular
Canals
Cochlea
(Utricle)
(Saccule)
Oval Window
Round Window
When the body undergoes acceleration, particularly when the acceleration is
rapidly changing in magnitude and or direction, the brain can quickly get confusing
signals from the inner ear, from muscle and joint proprioceptors, and from the eyes.
Often, dizziness, disorientation, nausea and vertigo result. Experience, training, and
mental attitude can be effective in reducing or even eliminating these effects.
To help us keep balance and orientation, and to help keep our eyes focused at one
place even while your head moves, each inner ear has a vestibular system of three
semicircular canals nearly at right angles (Fig. 3.3), holding a fluid (the endolymph),
and two other organs, called otoliths, the utricle and the vestibule. The semicircular
canals have nerve hairs cells which sense when endolymph fluid shifts when your
head rotates. The otoliths sense the direction of gravity and linear acceleration. They
contain tiny calcium stones (otoconia) which can move within a gel, and nerve hair
cells to detect this movement. The action of the gel on the otoconia is analogous to
the action of the springs on the mass shown in the Fig. 3.4. Within the linear elastic
range of the springs, the greater the acceleration, the greater the displacement of
the mass. Measuring this displacement is a measure of the acceleration, which can
be calibrated in g’s. Displacement of nerve hair cells in the gel in the utricle and
saccule of our inner ear sends linear acceleration information to the brain.