Download File - Learnin` with burton

Introduction to Health Science
Special Senses
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.
• 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.
• 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) and
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 first structure
of 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.
• The middle ear bones continue the passage of
sound vibrations. They also amplify the
vibrations twenty times.
Inner Ear
• 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.
E. 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 being. 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.
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.
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
• Also known as ringing in the ears. 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.
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.
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.
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.
Middle Ear and Bones
• Contains the middle ear bones.
• The middle ear bones continue the passage of
sound vibrations. They also amplify the
vibrations twenty times.