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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
TasteTaste occurs when specialized cells on the
tongue (chemoreceptors) detect chemicals resulting in nerve impulses which are sent to the brain for interpretation.
Mouth and TongueThe 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).
HearingHearing 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.
VisionThe 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)
EyeIris–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.
EyeRetina–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.
TouchTouch 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.
SkinThe 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.
www.kidshealth.org
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.
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.
TasteTaste 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 TongueThe 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)
HearingHearing 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 CanalTube 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 BonesContains 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 EarSemicircular 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.
TouchTouch is the detection of various amounts of
pressure by the skin. Nerve impulses are generated and sent to the brain for interpretation.
SkinThe 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.
VisionThe 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.
CorneaThe 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)
IrisThe colored portion of the eye which contains
two sets of muscles.Regulates the size of the pupil.
RetinaMost 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.
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, cognitive-communication, voice, swallowing, fluency, and other related disorders.
– Education – Masters Degree – Salary – National Average
65,000/yr
Audiologist
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.
• Education – Doctoral degree. Usually takes 4 years of graduate school to earn an Au.D.
• Salary - National average 63,000
Optometrists
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.
• Education – four year program at accredited optometry school.
• Salary - 96,000