Medical assisting Administrative and clinical procedures (5e) Chapter 35 Special senses
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CHAPTER
35
Special Senses
35-2
Learning Outcomes (cont.)
35.1 Describe the anatomy of the nose and the
function of each part.
35.2 Describe the anatomy of the tongue and the
function of each part.
35.3 Describe the anatomy of the eye and the
function of each part, including the accessory
structures and their functions.
35-3
Learning Outcomes (cont.)
35.4 Explain the visual pathway through the eye
and to the brain for interpretation.
35.5 Describe the causes, signs and symptoms,
and treatments of various disorders of the
eyes.
35.6 Describe the anatomy of the ear and the
function of each part, and the role of the ear
in maintaining equilibrium.
35-4
Learning Outcomes (cont.)
35.7 Explain how sounds travel through the ear
and are interpreted in the brain.
35.8 Describe the causes, signs and symptoms,
and treatments of various disorders of the
ears.
35-5
Introduction
•
Special senses – receptors in the head
–
–
–
–
Nose
Tongue
Eyes
Ears
• Touch is a generalized sense
• Stimulus nervous system brain
response
35-6
The Nose and the Sense of Smell
• Olfactory receptors
– Chemoreceptors – respond to changes in
chemical concentrations
– Chemicals must
be dissolved
in mucus
– Located in the
olfactory organ
35-7
The Nose and the Sense of Smell (cont.)
Activation of smell receptors
information sent to olfactory nerves
The information is sent along
olfactory bulbs and tracts
Cerebrum – interprets information
as a type of smell
Sensory Adaption
35-8
Apply Your Knowledge
You notice an odor coming from a patient when
you enter the exam room. Why would the patient
not be able to smell it?
ANSWER: After a few minutes, smell receptors undergo
sensory adaptation and no longer respond to the chemical,
and the patient can no longer smell the odor.
Very
Good!
35-9
The Tongue and the Sense of Taste
• Gustatory receptors – on the taste buds
• Taste buds
– Papillae of the tongue
– Roof of mouth
– Walls of throat
fewer than on tongue
}
Tongue
35-10
The Tongue and the Sense of Taste (cont.)
• Taste buds
– Taste cells ~ chemoreceptors that react to
chemicals in food and drink must be
dissolved in saliva to activate
– Supporting structures ~ fill in space
Tongue
35-11
The Tongue and the Sense of Taste (cont.)
• Taste sensations
– Sweet – tip
– Sour – sides
– Salty – tip and
sides
– Bitter – back
• Umami
– 5th basic taste
– Glutamate
• Spicy foods
– Activate pain
receptors
– Interpreted by
brain as “spicy”
Tongue
35-13
The Tongue and the Sense of Taste (cont.)
Taste sensation
Activation of
taste cells
Cranial
nerves
Gustatory cortex of cerebrum
interprets information as
a particular taste
35-14
Apply Your Knowledge
What are the four primary taste sensations and
where are their corresponding taste cells
located?
ANSWER: The four primary taste sensations are:
Sweet – concentrated on the tip of the tongue
Sour – concentrated on the sides of the tongue
Salty – concentrated on the tip and sides of the tongue
Bitter – concentrated on the back of the tongue
35-15
The Eye and the Sense of Sight
• Vision system
– Eyes
– Optic nerves
– Vision centers in
the brain
– Accessory
structures
• Eye
– Processes light to
produce images
– Three layers
– Two chambers
– Specialized parts
35-16
The Eye and the Sense of Sight (cont.)
• Outer Layer
– Sclera
– Cornea
• Tough outer layer
• Transparent
• Light cannot pass
through the sclera
• “Window” that
allows light into eye
• Sense receptors
– Limbus ~
corneal-scleral
junction
Eye
35-17
The Eye and the Sense of Sight (cont.)
• Middle layer – choroid
– Contains blood vessels
– Iris
• Muscle tissue relaxes and contracts to alter
the size of the pupil
• Regulates the amount of light entering the
eye
Eye
35-18
The Eye and the Sense of Sight (cont.)
• Middle layer (cont.)
– Ciliary body
~ wedge-shaped muscles
that controls the shape of the lens
– Lens
• Changes shape to focus light on retina
• Accommodation – the ability of the lens to
change shape
Eye
35-19
The Eye and the Sense of Sight (cont.)
• Inner layer – retina
– Optic disc – optic nerve enters retina
– Rods
• Sensitive to light
• Function in dim light – “night” and
peripheral vision
• Do not provide sharp image or detect color
Eye
35-20
The Eye and the Sense of Sight (cont.)
• Inner layer (cont.)
– Cones
• Function in bright light
• Sensitive to color and provide sharp images
• Enable differentiation of tones and hues of
color
35-21
The Eye and the Sense of Sight (cont.)
• Anterior chamber of the eye
– Front of lens
– Filled with aqueous humor – nourishes and
bathes anterior eye
• Posterior chamber
– Behind lens
– Contains vitreous humor – maintains shape of
eyeball and keeps the retina flat
Eye
35-23
Visual Accessory Organs
• Eye orbits – form a protective shell
around the eyes
• Eyebrows protect eyes
35-24
Visual Accessory Organs
• Eyelids
– Skin, muscle, and connective tissue
– Blinking
• Prevents surface from drying out
• Keeps foreign material out of eye
35-25
Visual Accessory Organs (cont.)
• Conjunctivas –
produce mucus to
keep the surface of
the eyeball moist
• Lacrimal
apparatus
– Lacrimal glands ~
produce tears
– Nasolacrimal
ducts ~ drain
tears into nose
35-26
Visual Accessory Organs (cont.)
• Extrinsic eye muscles
– Six per eye
– Move the eye
Levator palpebrae
superioris (cut)
Trochlea
Superior oblique
Optic Nerve
Superior rectus
Lateral rectus
Inferior Rectus
Inferior oblique
35-27
Apply Your Knowledge
Matching: ANSWER:
___
G Middle layer of eye
H Eye sockets
___
F Controls shape of lens
___
D Outer layer of eye
___
B Anterior chamber
___
A Tears
___
I Ability of lens to
___
change shape
E Posterior chamber
___
C Inner layer of eye
___
A.
B.
C.
D.
E.
F.
G.
H.
I.
Lacrimal glands
Aqueous humor
Retina
Sclera
Vitreous humor
Ciliary body
Choroid
Orbits
Accommodation
