Special Senses
Intro to health
Description of the Special
•
Senses
Smell
– Smell occurs when specialized cells in the nose
(chemoreceptors) detect chemicals resulting in
nerve impulses which are sent to the brain for
interpretation.
Nose
•
•
•
In the upper part of the nasal cavity are specialized nerve cells
called olfactory receptor cells. The olfactory receptor cells
contain hair called cilia to which the dissolved chemicals
attach.
Nerve impulses are transmitted from the olfactory receptors
cells to the olfactory bulb, to the olfactory nerve to the brain
where the sense of smell is interpreted.
Basic smells:
•
•
•
•
•
putrid (rotting food)
pungent (spicy)
floral (flowers)
ethereal (medicine smell)
mint
Taste

Taste occurs when specialized cells on the
tongue (chemoreceptors) detect chemicals
resulting in nerve impulses which are sent to the
brain for interpretation.
Mouth and Tongue



The sense organs that detect dissolved chemicals for the sense
of taste are the taste buds.
When the taste buds are stimulated by chemicals, they
generate nerve impulses which are sent to the brain for
interpretation.
There are five basic tastes:
◦
◦
◦
◦
◦
sweet (sugars and carbohydrates)
sour (acids)
salt (salt)
bitter (caffeine)
umami (protein and amino acids).
Hearing

Hearing involves the movement of sound vibrations
through the ear until they reach a specialized region in
the inner ear where nerve impulses are generated by
cells that detect movement (mechanoreceptors).
These nerve impulses travel to the brain where they are
interpreted as sound.
Outer Ear
Auricle
– The visible portion of the ear on
the side of the head.
– Composed of cartilage
– Captures the sound waves from
the environment and directs
them toward the auditory canal.
• Auditory Canal
– Tube lined with hair and wax.
– Assists in the passage of sound
waves to the middle ear.
– Provides protection for the ear as
particles, debris and dust are
trapped by the hair and wax.
•
Middle Ear
•
Tympanic Membrane
– Known as the eardrum, it is the first
structure of the middle ear.
– It vibrates with the sound waves and
passes the vibrations to the middle ear
bones.
•
Auditory Ossicles
– Three tiny bones in the middle ear that
continue the passage of sound
vibrations.
– They also amplify the vibrations twenty
times.
•
Eustachian Tube (auditory tube)
– Small tube extending from the middle ear
into the throat.
– Helps to equalize pressure inside the ear.
Inner Ear
•
Cochlea
– Snail shaped structure
composed of a series of
membrane-lined fluid-filled
canals that continue to pass
along the sound vibrations.
– The sound vibrations eventually
reach a specialized structure of
the inner ear called the Organ
of Corti where nerve impulses
are generated. The impulses
are transmitted to the brain
where they are interpreted.
Vision
The sense organs that respond
to light are the eyes.
 The light waves travel through
the eyes until they reach the
back of the eye called the
retina where nerve impulses
are generated by specialized
cells that are sensitive to light
(photoreceptors).
 The impulses travel to the
brain where they are
interpreted as visual images
and provide much
information about the
external world.

Eye
•
Eyelid
– Structures composed of skin, muscles, and lashes
– Protect the eye from foreign objects by the blink reflex.
– Moves tears along the surface of the eyeball to keep
the eyeball moist.
•
Conjunctiva
– Membrane lining the insides of the eyelids
and eyeball.
– Reduces friction during blinking
Eye
•
Sclera
– The white part of the eye.
– Provides protection and
shape to the eye.
•
Cornea
– The clear window of the front
part of the eye.
– Allows light waves to enter
the eye.
– Helps to bend the light
waves on to the back of the
eye (retina)
Eye

Iris
– The colored portion of the eye which contains two sets of
muscles.
– Regulates the size of the pupil to control the amount of
light entering the eye.
•
Pupil
– An opening in the center of the iris.
– Passage for light.
•
Lens
– Transparent disc shaped structure located behind the iris
and pupil.
– Focuses light waves on to the retina.
Eye

Retina
– Most inner layer of the eyeball. Located under the
sclera.
– Contains the photoreceptors that when stimulated
by light generate nerve impulses which are then sent
to the brain for interpretation.
Touch
Touch is the detection of various amounts of
pressure by the skin.
 Nerve impulses are generated by cells that are
sensitive to movement (mechanoreceptors)
and sent to the brain for interpretation.

Skin
The skin contains several different types of nerve
receptors in the skin which are sensitive to deep
pressure like poking or light touch.
 All regions of the skin are sensitive to touch. The
greatest number of touch receptors are found in the
fingers, toes, and face.
 Once the nerve impulses for touch are generated,
they are sent to the brain for interpretation.

Disorders of the Special
Senses
• Conjunctivitis
– Conjunctivitis is the
inflammation of the
conjunctiva.
– Can be caused by
viruses, bacteria, fungi,
and allergies. The most
common cause is viral.
– ”Pinkeye” is the
common term for
conjunctivitis.
Middle Ear Infection (Otitis
Media)

Causes of otitis media include
anything that causes the
Eustachian (auditory) tubes to
become blocked, inflamed or
irritated.
– Examples include colds, sinus
infections, allergies, tobacco smoke
or other irritants, babies who spend
a lot of time drinking on his or her
back.
Most common symptom is
earache
 Treatment includes antibiotics for
bactierial infections, use of warm
cloths and analgesics to relieve
pain and possible surgery if ear
infections recur frequently.

Deafness
Deafness is the complete or partial loss
of hearing in one or both ears.
• May be caused by a blockage of the
sound waves through the middle ear
by wax build up, foreign objects,
tumors or other matter.
•
– This type of deafness generally improves
once the blockage is removed.
•
Deafness may also result from damage
to the nerves or to the Organ of Corti.
– This type of deafness is usually irreversible
and may progressively get worse.
•
Treatment may include removal of the
blockage, hearing aids, or cochlear
implants.
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Myopia




Nearsightedness; when
a person sees near
objects clearly and
distant objects are
blurred.
Occurs when the
physical length of the
eye is greater than the
optical length.
Symptoms include
blurred vision of distant
objects, squinting,
eyestrain, and
sometimes headaches.
Treated with concave
lenses or LASIK surgery
Hyperopia
Farsightedness; when a
person sees far objects
clearly and near objects are
blurred.
 Occurs when the physical
length of the eyeball is too
small or the focusing power
of the lens is too weak.
 Symptoms include blurred
vision of close objects, eye
strain, aching eyes, and
headaches while reading.
 Treated with convex lenses.
Surgical options also
available.

Presbyopia
The normal loss of accommodation
power of the eye which occurs as a
consequence of aging. It occurs
because the lens becomes less flexible
and less able to bulge or
accommodate for near vision.
• Symptoms are similar to those of
farsightedness and include:
•
– blurring of close objects
– eye strain
– holding objects further from the face to
focus
– headaches or fatigue from focusing on
close objects.
•
Treatments may include the use of
reading glasses or bifocals.
Introduction
to
Health
Science
Special Senses
Vocabulary / Medical Terminology
•
•
•
•
•
•
•
•
Hearing – the sense by which sound is perceived.
Vision – the act or power of sensing with the eyes.
Taste – to distinguish flavor of using the mouth.
Touch - to bring a bodily part into contact with,
especially so as to perceive through the tactile
sense
Opthalmo – eye
- Blepharo – eyelid
Audio – hearing
- oto – ear
Glosso – tounge
- ectasis – dilation
-rraphy - suturing
Description of the Special Senses
•
Smell
– Smell occurs when chemicals are detected by
specialized cells in the nose resulting in nerve
impulses which are sent to the brain for
interpretation.
Nose
•
In the upper part of the nasal cavity, are
specialized nerve cells called olfactory receptor
cells. The olfactory receptor cells contain hair
called cilia to which the dissolved chemicals
attach.
•
Nerve impulses are transmitted from the olfactory receptors
cells to the olfactory bulb, to the olfactory nerve to the brain
where the sense of smell is interpreted.
Nose
•
Basic smells include
– putrid (rotting food)
– pungent (spicy)
– floral (flowers)
– ethereal (medicine smell)
– and mint.
Taste

Taste occurs when chemicals are detected by
specialized cells on the tongue resulting in
nerve impulses which are sent to the brain for
interpretation.
Mouth and Tongue

The sense organs that detect dissolved
chemicals for the sense of taste are the taste
buds. Taste buds are located in the tongue
and throughout the mouth.

When the taste buds are stimulated by
chemicals, they generate nerve impulses which
are sent to the brain for interpretation.
Mouth and Tongue
•
•
•
•
•
•
There are five basic tastes, although they are
not limited to specific parts of the tongue:
sweet (sugars and carbohydrates)
sour (acids)
salt (salt)
bitter (caffeine)
umami (protein and amino acids)
Hearing

Hearing involves the movement of sound
vibrations through the ear until they reach a
specialized region in the inner ear where nerve
impulses are generated. These nerve impulses
travel to the brain where they are interpreted
as sound.
Ear and Hearing
•
•
•
Outer Ear
The outer ear is composed of cartilage covered
with skin and hair.
Captures the sound waves from the
environment.
Auditory Canal
Tube lined with hair and wax.
 Assists in the passage of sound waves to the
middle ear.
 Provides protection for the ear as particles,
debris, and dust are trapped by the hair and
the wax.
 Part of the outer ear

Tympanic Membrane
•
•
Known as the eardrum, it is the structure that
divides the outer ear with the middle ear.
It vibrates with the sound waves and passes the
vibrations to the middle ear bones.
Middle Ear and Bones
Contains the middle ear bones (3)
Malleus (hammer), Incus (anvil), Stapes (stirrup)
 The middle ear bones continue the passage of
sound vibrations. They also amplify the
vibrations twenty times.
 Eustachian Tube: is a tube that links the
nasopharynx to the middle ear

Inner Ear
Semicircular Canals:
• A series of membrane-lined fluid-filled canals that
continue to pass along the sound vibrations.
 Cochlea:
• is filled with a watery liquid, which moves in response
to the vibrations coming from the middle ear
 Organ of Corti :

• The sound vibrations eventually reach a specialized structure
of the inner ear called the where nerve impulses are
generated. The impulses are transmitted to the brain where
they are interpreted.
Touch

Touch is the detection of various amounts of
pressure by the skin. Nerve impulses are
generated and sent to the brain for
interpretation.
Skin
The skin contains several different types of nerve
receptors in the skin which are sensitive to deep
pressure like poking or light touch.
 All regions of the skin are sensitive to touch. The
greatest number of touch receptors are found in the
fingers, toes, and face.
 Once the nerve impulses for touch are generated,
they are sent to the brain for interpretation.

Vision
The sense organs that respond to light are the
eyes.
 The light waves travel through the eyes until the
reach the back of the eye called the retina
where nerve impulses are transferred to the
optic nerve.
 The impulses travel to the brain where they are
interpreted as visual images and provide much
information about the external world.

Eye
•
Eyelid
– Structures composed of skin, muscles, and lashes
– Protect the eye from foreign objects by the blink
reflex.
– Moves tears along the surface of the eyeball.
Conjunctiva
Membrane lining the insides of the eyelids and
eyeball.
 Reduces friction during blinking

Sclera
The white part of the eye.
 Provides protection and shape to the eye.

Cornea
The clear window of the front part of the eye.
 Allows light waves to enter the eye.
 Helps to bend the light waves on the back of
the eye (retina)

Iris
The colored portion of the eye which contains
two sets of muscles.
 Regulates the size of the pupil.

Pupil
An opening in the center of the iris.
 Passage for light.

Lens
Transparent structure located behind the iris
and pupil.
 Focuses light waves on to the retina.

Retina
Most inner layer of the eyeball. Located under
the sclera.
 Contains the nerves that when stimulated by
light generate nerve impulses which are then
sent to the brain for interpretation.

Diseases and Disorders
Conjunctivitis
– Conjunctivitis is the
inflammation of the
conjunctiva.
– Can be caused by
viruses, bacteria, fungi,
and allergies. The most
common cause is viral.
– ”Pinkeye” is the
common term for
conjunctivitis.
Otitis Media



Otitis media is a middle
ear infection.
Causes of otitis media
include anything that
causes the Eustachian
(auditory) tubes to
become blocked,
inflamed or irritated.
Examples include colds,
sinus infections, allergies,
tobacco smoke or other
irritants, babies who
spend a lot of time
drinking on his or her
back.
Tinnitus
Tinnitus is the term used for any ear noise when there is
not outside source for the sounds.
• Is common. Most people have experienced it – and it
only lasts for a few minutes.
• Causes are unknown but may be associated with an
ear infection, ear injury, and as a reaction to various
drugs including alcohol, caffeine, antibiotics and
aspirin.
• Also known as ringing in the ears.
•
Vertigo






Also known as dizziness,
light headedness, or a
feeling that the room is
spinning or moving.
Occurs when:
there is not enough
blood to the brain
changing the position
of the head
a viral infection of the
inner ear
or Meniere’s disease
(an inner ear disease).
Myopia



Nearsightedness;
when a person sees
near objects clearly
and distant objects
are blurred.
Occurs when the
physical length of the
eye is greater than
the optical length.
Symptoms include
blurred vision of
distant objects,
squinting, eyestrain,
and sometimes
headaches.
Hyperopia



Farsightedness; when a
person sees far objects
clearly and near objects
are blurred.
Occurs when the physical
length of the eyeball is
too small or the
focusing power of the
lens is too weak.
Symptoms include blurred
vision of close objects,
eye strain, aching eyes,
and headaches while
reading.
Careers Associated With the Special
Senses
•
Speech-Language Pathologist
– Speech-language pathologists,
sometimes called speech
therapists, assess, diagnose, treat,
and help to prevent speech,
language, cognitivecommunication, voice, swallowing,
fluency, and other related
disorders.
– Education – Masters Degree
– Salary – National Average 65,000/yr
Audiologist


• Education – Doctoral
degree. Usually takes
4 years of graduate
school to earn an
Au.D.
• Salary - National
average 63,000

Audiologists work with
people who have
hearing, balance, and
related ear problems.
They examine individuals
of all ages and identify
those with the symptoms
of hearing loss and other
auditory, balance, and
related sensory and
neural problems.
They then assess the
nature and extent of the
problems and help the
individuals manage them.
Optometrists


• Education – four
year program at
accredited
optometry school.
• Salary - 96,000
Optometrists provide most
primary vision care. They
examine people’s eyes to
diagnose vision problems
and eye diseases, and
they test patients’ visual
acuity, depth and color
perception, and ability to
focus and coordinate the
eyes.
Optometrists prescribe
eyeglasses and contact
lenses and provide vision
therapy and low-vision
rehabilitation.
Eye Doctor Clip