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The sensory system includes any organ or part involved in
the perceiving and receiving of stimuli.
Sight
Hearing
Five Senses
Taste
Smell
Touch
All sensory organs contain specialized receptor cells that receive
stimuli.
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eyebrow
Sight-the Eye
eyelid
•Contains about 70% of all the
receptors in the body
•Each eye is a sphere consisting of
three layers:
-outer layer (eyelid)
-middle layer (vascular layer)
-interior layer (retinal layer)
eyelashes
Note: Eyebrows and eyelashes keep foreign
particles from entering the eye.
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The Eye (cont’d)
sclera
•The anterior surface of the eye and posterior
surface of the eyelid are lined with a mucous
membrane called the conjunctiva
•The sclera is the white posterior section of
the eye that supports the eyeball
•The cornea is transparent, lacks blood vessels
and bends or refracts light rays as they enter
the eye
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The Middle Layer
•The vascular layer of blood vessels
which consists of a thin posterior
membrane called the choroid
•The Ciliary Body is anterior and contains
the ciliary muscles used for focusing the
eye
•The ciliary body contracts to change the
shape of the lens in a process called
accommodation
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Other Eye Structures
•Pupil black circular center of
the eye
•Lens colorless, transparent
body behind the iris
iris
pupil
•Iris colored part of the eye
•Retina light sensitive membrane that decodes
the light waves and sends information to the
brain
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The Retinal Layer
•Interior layer of the eye
•Contains a light sensitive membrane called the retina
which consists of several layers
Layers of the Retina
Neuroretina
•Thick layer of nervous tissue consisting of specialized nerve
receptor cells called rods and cones
Optic Disk
•Region where the retina connects to the optic nerve
Macula lutea
•Small yellowish area in the center of the retina directly behind
the lens which has a depression in the center called the fovea
centralis
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The Eyeball
• Is divided into three cavities called chambers:
-Anterior chamber (between the cornea and iris)
-Posterior chamber (between the iris and lens)
-Vitreous chamber (posterior to the lens and is the
largest chamber)
Both the anterior and posterior chambers are filled with a thin
watery liquid called the aqueous humor. Vitreous humor is a
gelatinous substance that supports the eye.
Note: lacrimal glands secrete moisture into the tear
ducts
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The Eyeball Part 2
Sclera
Vitreous humor
Iris
Cornea
Pupil
Lens
Aqueous humor
Anterior
Anterior
chamber
cavity Posterior
chamber
Ciliary body
Optic disk
Optic nerve
Fovea centralis
Retina
Choroid
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Related disease
Amblyopia - dropping of vision
without a visible anatomic or
refractive basis.
Signs- Dropping of an acuteness of
the central vision, usually
appreciable, frequent disturbance of
visual bracing. Glasses of vision do
not improve. The specified
disturbances gradually get more and
more proof, in some cases
irreversible character. Objectively
any changes of refracting mediums
and are not present a bottom of an
eye.
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pinna
Hearing and Equilibrium – the Ear
external
auditory
meatus
External Ear
Middle Ear
•Auricle (pinna)
-funnel-like structure
that leads through the
temporal bone of the
skull
•Tympanic cavity where the
tympanic membrane is located
and the ossicles:
-malleus (hammer)
-incus (anvil)
-stapes (stirrup)
•Middle ear connects to the
pharynx through the
eustachian tube which helps
equalize air pressure
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•External auditory
meatus
-contains glands that
secrete
Parts of Parts
the Earof
the Ear
Malleus
Incus
Stapes
Auricle
Cochlea
Oval window
Round window
Tympanic cavity
Tympanic
membrane
(eardrum)
Auditory tube
Pharynx
External auditory
meatus
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Osseus labyrinth
membranous labyrinth
Cochlea
Perilymph
Inner ear
Semicircular canals
Endolymph
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Cochlea
•Snail-shaped structure located in the labyrinth
•Important for hearing
•Divides into:
-scala vestibuli (leads from the oval window to the apex of the
cochlea)
-scala tympani (leads from the apex of the cochlea to the round
window)
•Contains a basilar membrane that has hairlike receptor cells
located in the organ of Corti on the membrane’s surface
NOTE: The hairlike receptor cells move back
and forth in response to sound waves .
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Hearing
•The hair like receptors located in the organ of Corti
move back and forth in response to sound waves, then
send messages via neurotransmitters to the brain for
interpretation
•Sound intensity (decibels) heard by the normal ear
ranges from 40 dB to 140 dB
Equilibrium
•The ability to maintain a steady balance
when still or moving
•Otoliths are small calcifications that
move to maintain gravitational balance
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Related disease
Labyrinthitis
Symptoms and indications: Severe dizziness and nystagmus
(involuntary, quick movements of the eyes from side to side, up
and down or circular). Also, loss of hearing, nausea, vomiting,
falling and complete loss of balance. This is a serious condition and
the person requires immediate medical attention.
Treatment: Depends on cause, but may involve surgery for
drainage of fluid from the labyrinth or removal of infected bone
cells from the mastoid process (a part of the temporal bone),
which is called mastoidectomy. Intensive therapy with antibiotics
or antiviral drugs may be required, possibly given intravenously.
With prompt treatment, recovery of hearing and from symptoms is
usually good but complications can arise. The person should rest in
bed until all symptoms have disappeared.
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The skin
Skin is the largest organ in your body and weighs about 12% of your
total body weight! It is always active, making sure your main barrier to
invaders is secure, and replaces itself about once every two weeks. Skin
has very important jobs, the most important of all is to make sure it
holds all your inside bits, inside! Your skin is very tough and acts as
protection against microbes and other things that could damage your
internal organs. It is also waterproof, which is why you don’t swell up
and slosh around when it rains or if you go swimming! One of the
greatest things your skin does is to sense the world you can touch. Your
skin tells you about the temperature, shape and weight of the world
around you, as well as telling you if things are painful, sharp, hard, soft
or cuddly!
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Your skin is made up of three thick layers
•
•
•
The outside layer is called the epidermis and this is the layer you see
every day. This layer is touch and acts as protection for your body.
The middle layer of your skin is called the dermis. Your dermis is made
up of a protein called collagen that makes it stretchy. It has nerve
endings that send signals to your brain to help it to decide if the things
you touch are hot or cold, hard or soft, flat or pointy.
The final layer of your skin is called the subcutaneous layer and it is
where fat is stored. Some fat is very useful as it protects your body
when you bump into things or fall over.
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Touch, Pain, and Temperature – the Skin
Skin receptors can
sense the
Touch
following:
Pressure
Pain
Temperature
Injury
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Skin cancer:
Related disease
Skin cancer is the most common form of human cancer. It is estimated that
over 1 million new cases occur annually. The annual rates of all forms of skin
cancer are increasing each year, representing a growing public concern. It has
also been estimated that nearly half of all Americans who live to age 65 will
develop skin cancer at least once.
Common sense preventive techniques include
•limiting recreational sun exposure
•avoiding unprotected exposure to the sun during peak radiation times (the
hours surrounding noon)
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Your nose and smell
Your nose is the main olfactory organ – that is,
the organ that allows you to smell. To do this
it needs help from other parts of the olfactory
system.
• In the roof of the nasal cavity (the space is behind your nose,
right in the middle of your face), the olfactory epithelium (that
is, the area of skin that allows you smell) has tiny receptors that
can recognize different smells that are in the air around us.
There are at least 10 million receptors in your nose!! Between
them, these receptors can recognize about 10,000 different
types of smells
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Did you know..?
Believe it or not, your sense of smell helps you to recognize
tastes! It works with the tongue to allow us to get the full flavor
and taste of food and drinks. Your sense of smell is over 10,000
times more sensitive than your sense of taste!
• Smells help train your brain – when you smell something for the
first time, your brain remembers it when you smell it again. This
memory is linked to the part of your brain that controls emotions.
So, if you are happy or sad when you eat or drink something, you
may feel happy or sad when you eat or drink it again!
•
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Related disease:
Chronic atrophic rhinitis is a chronic inflammation of nose
characterized by atrophy of nasal mucosa, including the
glands, turbinate bones and the nerve elements supplying the
nose. Chronic atrophic rhinitis may be primary and secondary.
Special forms of chronic atrophic rhinitis are rhinitis sicca
anterior and ozaena.
• Treatment options Treatment of atrophic rhinitis can be
either medical or surgical.
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Your mouth and taste
Your tongue is a very hard working muscle!
Actually, it is lots of little groups of muscles
that go in different directions to do lots of
different jobs. You use your tongue to talk, to
chew, to swallow, to sing and to taste.
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The papillae on your tongue are where you find your
taste buds. When you were born, you had about
10,000 taste buds, but as you get older, this number
will become less and less. When you are old enough
to retire, you may only have 5,000 taste buds, which
is why some foods taste stronger to you than they
would to your parents or grandparents!
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Taste buds can pick our sweet, sour, bitter and salty
flavors on different parts of your tongue – have a look at
where this is on the diagram.
Each bud has lots of tiny hairs that can sense flavors and
send messages to your brain. Sometimes these are good
but sometimes these are bad – maybe you don’t like a
flavor or it is something dangerous to eat or drink. When
you are cold, your taste buds don’t work as well so you
may be able to eat or drink a flavor you don’t normally
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like!
Related disease:
Loss of Taste
Loss of taste is caused by interruption of the transfer of taste
sensations to the brain, or by a problem with the way the brain
interprets these sensations. Although taste problems are common,
complete loss of taste is rare.
What causes loss of taste?
Inflammation and infection of the upper respiratory tract, sinuses,
mouth, and tongue can result in loss of taste. Symptoms may arise
from inflammatory conditions, infections, or diseases that affect the
taste buds of the tongue responsible for the sensation of taste.
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Careers:
Allergist
Works with people who have hearing, balance, and related ear
problems. Using technology and computers they provide essential
hearing services in a variety of settings including research,
manufacturing, industry and private practice.
Training and Qualifications - what you have to do to be an
Audiologist
Formal education and training requirements for audiologists includes
a Masters degree from an accredited college. Many states require a
Doctorate in Audiology as the minimum standard. Specialty
certification requires an additional training module and a minimum
number of hours practicing as an Audiologist. A standardized exam
is also part of the process.
The median expected salary for a typical Audiologist in the United
States is $68,922.
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Ophthalmogist
Ophthalmologists are physicians who diagnose and treat diseases of the eye,
including glaucoma and cataracts; vision problems such as nearsightedness; and
eye injuries. Optometrists and family doctors often refer patients with
serious eye conditions to ophthalmologists. Because of their extensive
training, ophthalmologists can often link eye problems to other disorders.
Education and Training Requirements
Ophthalmologists need extensive training after high school: four years of
college, four years of medical school, one year of internship, and three years
of training as hospital residents in ophthalmology. After their internships,
students take a series of exams to become licensed to practice general
medicine. After their residencies, ophthalmologists must pass exams and
other requirements for certification in their specialty.
Salary: Median—$199,423 per year
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Otolaryngologist
Examines diagnoses and treats disorders, diseases, and
injuries of the ear, nose and throat. Consults with
patients to determine the appropriate course of
treatment. Recommends and orders tests to determine
extent of disease or help diagnose condition.
Education and Training Requirements
Requires a degree in medicine from an accredited
school and is licensed to practice. May require at least
2-4 years of otolaryngology experience. Familiar with
standard concepts, practices, and procedures within a
particular field.
$151,696 to $300,743 per year.
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