Transcript Olfactory Sense

ST110
Concorde Career College, Portland
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Define the term sense.
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Describe the functions of the sensory system.
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List and identify the structures of the sensory
system and describe the function of each.
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Describe the mechanism by which the
sensory system helps to maintain
homeostasis.
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Describe common diseases, disorders, and
conditions of the sensory system including
signs and symptoms, diagnosis, and available
treatment options.
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Demonstrate knowledge of medical
terminology related to the sensory system
verbally and in the written form.
Sense
The terms sense is defined as the perception of
any stimulus.
From the Latin: sentio - to feel or perceive
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Special senses - localized in a special sense organ
 Vision
 Hearing and Equilibrium
 Gustation
 Olfaction
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General senses - widely distributed throughout the
body
 Touch, pressure, temperature, proprioception, pain
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Nervous system component that detects a stimulus
that results in experience of a sensation. May be
a/an:
 Free dendrite of a sensory neuron (pain receptor)
 End-organ (modified ending) found on the end of an
afferent neuron (touch and temperature receptors)
 Special cell associated with an afferent neuron (rods and
cones of the eye)
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Sensory
 Thermoreceptors (temperature - skin)
 Photoreceptors (light - retina)
 Chemoreceptors (chemicals - tongue, nose)
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Mechanical - respond to movement
 Stretch (skin, muscle - proprioception)
 Pressure (skin)
 Vibration (hearing, balance)
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Orbit
Eyelids
Eyelashes and eyebrow
Conjunctiva
Lacrimal apparatus
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Frontal
Sphenoid
Ethmoid
Maxilla
Malar (zygoma)
Lacrimal
Palate
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Protect the anterior
one third of the eyeball
 Blinking - lubrication
▪ Levator palpebrae
▪ Blephar/o
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Help keep foreign
matter out of the eyes
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Thin membrane that
lines the eyelid and
covers the anterior
portion of the eyeball
Tears lubricate the eye
and wash away foreign
objects
 Tears contain an
enzyme that protects
the eye from infection
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Tunics (coats) of the Eye
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Outer - sclera
Middle - choroid
Inner - retina
Pathway of Light Rays
and Refraction
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Cornea
Aqueous humor
Lens
Vitreous humor
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Fovea centralis
 Sharpest vision
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Optic disk or “blind spot”
 No receptors
Rods - function in dim
light (dark adaptation)
 Cones - function in
bright light (color and
sharp images)
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 Three types - red, green,
blue
The color blindness test consists of a
set of five charts. Each chart
shows a number in one color on
a different background color.
People with normal color vision
will have no problem seeing the
numbers on the charts, but
people with color blindness will
see only random colored dots.
Seventy-five percent of color
blind people have poor green
perception. Of the remaining,
24% have poor red perception,
and 1% are affected by a rare
tritan type.
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Superior oblique
Inferior oblique
Superior rectus
Inferior rectus
Lateral rectus
Medial rectus (not
shown)
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Iris
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Ciliary Body
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Accommodation
 Adaptation of the lense to facilitate focus
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Convergence/Divergence
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Emmetropia
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20/20
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Snellen Chart
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1st number-distance from the chart (20ft)
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2nd number- deviation from the norm based on
ability to read chart
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Myopia nearsightedness
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Hyperopia farsightedness
A. Papilledema
B. Deep retinal
hemorrhages
C. Neovascularization
D. Cotton wool spots
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Increase IOP
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Loss of
vision/blindness
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Dry eye
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Keratitis
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Iritis
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Conjunctivitis
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Corneal transplant
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“cross eyed”
“wall eyed”
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External
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Middle
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Inner
Pinna (auricle)
Meatus
External auditory canal
(contains ceruminous
glands)
 Tympanic membrane
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Tympanic membrane
Ossicles
 Malleus (hammer)
 Incus (anvil)
 Stapes (stirrup)
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Oval window
Eustachian tube
Mastoid sinus
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Bony labyrinth - contains perilymph
 Vestibule
 Semicircular canals
 Cochlea
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Membranous labyrinth - contains endolymph
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Air Conduction- sound waves enter the ear through the pinna
and travel down the auditory canal and strike the TM
between the outer and middle ear
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Bone Conduction- bones vibrate and send
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Sensorineural Conduction- sound vibrations reach inner ear
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Organ of Corti
 Cochlear branch of the vestibulocochlear nerve
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Vestibular apparatus
Vestibular branch of
the vestibulocochlear
nerve
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Impacted cerumen
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Otalgia
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Otitis
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Otorrhagia
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Eustachitis
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Mastoiditis
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Myringitis
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Otosclerosis
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Otitis Media
Otitis Media
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Labryinthitis
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Meniere’s Syndrome
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Tinnitus
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Vertigo
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Otoplasty
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Mastoidectomy
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Myringotomy
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Stapedectomy
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Deafness
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Conductive Hearing Loss
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Noise-Induced Hearing Loss
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Sensorineural Loss
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Presbycusis
Tongue
 Taste buds
 Fissures
 Sweet (c)
 Sour (d)
 Salty (e)
 Bitter (f)
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Cranial nerves VII
(facial) and IX
(glossopharyngeal)
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Taste bud-modified epithelial cells that function as
receptors
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Contain microvilli
Smell
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Olfactory epithelium
Olfactory bulb
Olfactory nerve
Temporal lobe
Taste is affected by olfaction
Chemoreceptors-sense smells and taste
Nociceptors-pain
Thermoreceptorstemperature
 Mechanoreceptors
Changes in pressure/
movement
 Photoreceptors- in eyes, respond to light energy
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Sensations- Feelings that occur when the
brain receives sensory impulse from PNS.
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Perceptions-conscious awareness of
sensation after interpretation.
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Involve the receptors associated with skin,
muscles, joints and visceral organs.
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Touch- tactile receptors located in the skin or
just beneath it.
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Pressure- stimulation of receptors in deeper
tissue
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Touch and Pressure
 Free ends of sensory nerve fibers
 Meissner’s corpuscles
 Pacinian corpuscles
Touch
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Tactile corpuscles
 Dermis
 Lips
 Tip of tongue
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Receptors for deep touch
 Located subcutaneously, near the joints, muscles,
and other deep tissues
 Are active even when the skin is anesthetized
resulting in a consciousness of pressure sensation
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Thermal- perceptions of degrees of warmth
and coolness
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Temperature- free nerve endings located
beneath skin
 Heat receptors
 Cold receptors
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Receptors are free nerve endings in the skin
Separate receptors for heat and cold
Hypothalamus initiates internal responses
according to the temperature of the blood
passing through the brain
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Pain- free nerve endings that are stimulated
when tissues are damaged.
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Acute
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Chronic
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Occurs very rapidly
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Not felt in deeper tissues
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Sharp/stabbing pain
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Slower onset
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Builds slowly in intensity (sec. or min.)
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AKA referred pain
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Pg 194 fig 9-1
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Sensations of lengthening and
stretching muscles
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Golgi tendon organs
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Muscle spindles
Position
Receptors located in
muscles, tendons, and
joints
 Relay information
concerning location of
body parts to one another
 Information processed in
the cerebellum
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