Transcript Inner ear - YISS-Anatomy2010-11

SPECIAL SENSES
Special Senses
• Vision
• Hearing and balance
Visual System: Accessory
Structures
• Eyebrows: shade; inhibit sweat
• Eyelids (palpebrae) with
conjunctiva.
• Conjunctiva: thin transparent
mucous membrane
• Eyelashes: double/triple row of
hairs.
Lacrimal Apparatus
• Lacrimal gland:
produces tears to
moisten, lubricate,
wash. Tears pass
through ducts and then
over eye.
• Lacrimal canaliculi:
collect excess tears
through openings called
puncta.
• Nasolacrimal duct:
opens into nasal cavity
Extrinsic Eye Muscles
Anatomy of the Eye
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Three coats or tunics:
Fibrous: sclera (whites) and cornea (transparent)
Vascular: choroid (w/in sclera), ciliary body (attaches lens), iris
Nervous: retina
Retina
• Rods – sensory cells used in low
illumination
• Cones – sensory cells that detect color
– 3 types of pigment – blue, red, green
• Most images focused on fovea centralis
(most concentrated area of cones)
• Rods and cones synapse with bipolar cells
– which then synapse with ganglion cells
– which form the optic nerves
Focusing
The Ear
• External ear: hearing. Terminates at eardrum (tympanic
membrane). Includes auricle (pinna) & external auditory meatus
• Middle ear: hearing. Air-filled space containing auditory
ossicles
• Inner ear: hearing and balance. Interconnecting fluid-filled
tunnels and chambers within the temporal bone
Inner
Ear
Auditory Function
• Sound waves funnel down auricle and
external acoustic meatus to vibrate tympanic
membrane (ear drum)
• Tympanic membrane vibrations passed along
auditory ossicles (ear bones) to inner ear
• These vibrations cause lymph to vibrate
which moves the stereocilia of inner hair cells
• Bending of stereocilia causes mechanical
opening of ion channels – depolarization
• Depolarization leads to action potentials in
vestibulocochlear nerve
A
B
C
D
E
F
Practice Questions
The receptors for sound reception and
equilibrium are located in the
A. in the outer, middle and inner cavities.
B. inner ear cavity.
C. middle ear cavity.
D. in the middle and inner ear cavities.
E. outer ear cavity.
When a person cries, he or she tends to keep on wiping
their dripping nose. The nose drips because
A. special secretory glands are located in the nose start to
produce secretions into the nose.
B. lacrimal gland secretions wash the eyeball and drain
into the lacrimal duct which empty into the nasal cavity.
C. the nasal mucosa is sensitized to produce mucous into
the nose.
D. the eyeball produces tears that drain into the
nasolacrimal duct and then into the nose.
E. when a person cries olfactory mucosa are sensitized to
increase secretions into the nose.
When focusing on a distant object the lens
is
A. more concave.
B. more flattened.
C. more convex.
D. not changed.
The auditory tube allows pressure
equalization between the middle ear and
the external environment.
True
False
The semicircular canals respond to
rotational movements.
True
False
The size of the pupil is dependent on the
contraction of the muscles of the iris.
True
False
The rods of the retina operate in bright light
and provide high acuity vision.
True
False
Impulses from the olfactory epithelium are
sent to the brain via cranial II.
True
False
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The cornea is part of the vascular tunic.
True
False