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ST110Concorde Career College, Portland
Define the term sense.
Describe the functions of the sensory system.
List and identify the structures of the sensory system and describe the function of each.
Describe the mechanism by which the sensory system helps to maintain homeostasis.
Describe common diseases, disorders, and conditions of the sensory system including signs and symptoms, diagnosis, and available treatment options.
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
Special senses - localized in a special sense organ Vision Hearing and Equilibrium Gustation Olfaction
General senses - widely distributed throughout the body Touch, pressure, temperature, proprioception,
pain
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)
Sensory Thermoreceptors (temperature - skin) Photoreceptors (light - retina) Chemoreceptors (chemicals - tongue,
nose)Mechanical - respond to movement
Stretch (skin, muscle - proprioception) Pressure (skin) Vibration (hearing, balance)
OrbitEyelidsEyelashes and eyebrowConjunctivaLacrimal apparatus
Frontal Sphenoid Ethmoid Maxilla Malar (zygoma) Lacrimal Palate
Protect the anterior one third of the eyeball Blinking -
lubrication▪ Levator palpebrae
▪ Blephar/o
Help keep foreign matter out of the eyes
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
Tunics (coats) of the Eye
Outer - sclera Middle - choroid Inner - retina
Pathway of Light Rays and Refraction
Cornea Aqueous humor Lens Vitreous humor
Fovea centralis Sharpest vision
Optic disk or “blind spot” No receptors
Rods - function in dim light (dark adaptation)
Cones - function in bright light (color and sharp images) 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.
Superior oblique Inferior oblique Superior rectus Inferior rectus Lateral rectus Medial rectus (not
shown)
Iris Ciliary Body
Accommodation Adaptation of the lense to facilitate focus
Convergence/Divergence
Emmetropia
20/20
Snellen Chart
1st number-distance from the chart (20ft)
2nd number- deviation from the norm based on ability to read chart
Myopia - nearsightedness
Hyperopia - farsightedness
A. Papilledema
B. Deep retinal hemorrhages
C. Neovascularization
D. Cotton wool spots
Increase IOP
Loss of vision/blindness
Dry eye
Keratitis
Iritis
Conjunctivitis
Corneal transplant
“cross eyed”“wall eyed”
External Middle Inner
Pinna (auricle) Meatus External auditory
canal (contains ceruminous glands)
Tympanic membrane
Tympanic membrane Ossicles
Malleus (hammer) Incus (anvil) Stapes (stirrup)
Oval window Eustachian tube Mastoid sinus
Bony labyrinth - contains perilymph Vestibule Semicircular canals Cochlea
Membranous labyrinth - contains endolymph
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
Bone Conduction- bones vibrate and send
Sensorineural Conduction- sound vibrations reach inner ear
Organ of Corti Cochlear branch of the vestibulocochlear nerve
Vestibular apparatus
Vestibular branch of the vestibulocochlear nerve
Impacted cerumen
Otalgia
Otitis
Otorrhagia
Eustachitis
Mastoiditis
Myringitis
Otosclerosis
Otitis Media
Otitis Media
Labryinthitis
Meniere’s Syndrome
Tinnitus
Vertigo
Otoplasty
Mastoidectomy
Myringotomy
Stapedectomy
Deafness
Conductive Hearing Loss
Noise-Induced Hearing Loss
Sensorineural Loss
Presbycusis
Tongue Taste buds Fissures
Sweet (c) Sour (d) Salty (e) Bitter (f)
Cranial nerves VII (facial) and IX (glossopharyngeal)
Taste bud-modified epithelial cells that function as receptors
Contain microvilli
Smell Olfactory epithelium Olfactory bulb Olfactory nerve Temporal lobe
Taste is affected by olfaction
Chemoreceptors-sense smells and taste Nociceptors-pain Thermoreceptors-temperature MechanoreceptorsChanges in pressure/movement Photoreceptors- in eyes, respond to light
energy
Sensations- Feelings that occur when the brain receives sensory impulse from PNS.
Perceptions-conscious awareness of sensation after interpretation.
Involve the receptors associated with skin, muscles, joints and visceral organs.
Touch- tactile receptors located in the skin or just beneath it.
Pressure- stimulation of receptors in deeper tissue
Touch and Pressure Free ends of sensory nerve fibers Meissner’s corpuscles Pacinian corpuscles
Touch
Tactile corpuscles Dermis Lips Tip of tongue
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
Thermal- perceptions of degrees of warmth and coolness
Temperature- free nerve endings located beneath skin Heat receptors Cold receptors
Receptors are free nerve endings in the skin
Separate receptors for heat and coldHypothalamus initiates internal
responses according to the temperature of the blood passing through the brain
Pain- free nerve endings that are stimulated when tissues are damaged.
Acute
Chronic
Occurs very rapidly
Not felt in deeper tissues
Sharp/stabbing pain
Slower onset
Builds slowly in intensity (sec. or min.)
AKA referred pain
Pg 194 fig 9-1
Sensations of lengthening and stretching muscles
Golgi tendon organs
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