SMELL NO GOOD. TASTE NO GOOD. Hear no evil See no evil..
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Intro Millions of sensory neurons Two categories
general/special Most numerous general General receptors sense
touch, temp., pain, reflexes, homeostasis responses Special
receptors sense vision, hearing, balance, taste, smell,
reflexes
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Receptor response Receptors respond to stimuli by converting
them to nerve impulses Receptors are the dendrite endings Receptors
vary according to their jobs heat, pain, etc Receptor potential
determines the response required for the stimulus These impulses
travel to spinal cord to be determined as hot, cold, etc
(sensation) Adaptation allows for decrease of response when
necessary
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Distribution of receptors Special sensory receptors nose,
tongue, eye, ear General sensory receptors skin, mucosa, connective
tissue, muscle, tendons, joints, viscera (somatic senses) Touch
receptors very dense on hand and sparse on back
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Classification of receptors Exteroceptors Visceroceptors
Proprioceptors
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Exteroceptors On or near body surface external stimuli
Cutaneous receptors Pressure, touch, pain, temp.
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Visceroceptors Interoceptors Internally body organs internal
environment Stimulated by pressure, stretching, chemical changes
from blood vessels, organs, intestines Hunger, thirst
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Proprioceptors Specialized visceroceptor Less numerous and more
specialized Limited to skeletal muscle, joint capsules, and tendons
Info about body movement, orientation to space dont have to look to
find hand
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Classification by stimulus detected Mechanoreceptors activated
by mechanical stimuli (pressure to skin) Chemoreceptors change in
concentration of chemicals blood glucose, oxygen, etc.
Thermoreceptors temp. changes Nociceptors activated by intense
stimuli of any type that results in tissue damage welding light,
battery acid, etc. Photoreceptors eye only light receptors
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Classification by structure Free nerve endings Encapsulated
nerve endings
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Free birds.. Simplest, most common Most widely distributed Not
in the brain Primary receptor for pain Responsible for itch, sting,
tickling, touch, movement, heat, cold Acute sharp, intense,
localized sensation Chronic persistent pain, dull, aching
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Caged birds Six types Covering over dendrite end Activated by
mechanical response Vary in size, shape, and distribution Touch
receptors in none hair areas Krauses end bulbs- mucus membrane low
frequency vibration, cold receptor Ruffinis corpuscle deep in
dermis persistent touch receptor (crude)- allows for grasp for long
periods of time and still sense stimuli
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Caged birds cont.. Stretch receptors muscle/tendon determines
strength of contraction and duration maintains posture
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WHIFF CHECK..SMELL!
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Olfactory receptors Upper surface of nasal cavity
Chemoreceptors Gas molecules/chemicals dissolve in mucus lining
Cilia help to mix the mucus as the solvent Air flows around and
down the airway not to the top usually That is why you sniff for
better clarity Filed in temporal lobe Abnormalities sometimes
impede normal processing
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SO, BE THANKFUL THAT YOU CAN STOP AND SMELL THE ROSES!
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Yum! Papillae contain taste buds each has 50- 125
chemoreceptors Determine texture, feel Taste receptors are all over
the tongue Old maps are incorrect Taste is stimulated by chemicals
dissolved in saliva Four flavors detected fifth metal?
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Taste to the brain.. Gustatory cells in taste buds begin
assimilation of taste in seconds Anterior two thirds of the tongue
to facial nerve to glossopharyngeal nerve to the vagus nerve to
medulla oblongata and the thalamus to the cerebral cortex in
parietal lobe
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WHAT DID YOU SAY! External ear auditory meatus 3 cm in,
forward, down Modified sweat glands produce wax Mechanoreceptors
pick up vibrations in the cilia which are transmitted into the bony
structures of the inner ear
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Divisions External Middle Inner
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External ear Flap modified trumpet (auricle/pinna) Tube from
the auricle external auditory meatus (ear canal) 3cm in, forward,
down meds. Pull up and back Over-production of wax will cause
pain/deafness End of meatus is the tempanic membrane - eardrum
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Middle ear Tempanic cavity Three tiny ossicles (bones) Malleus,
incus, stapes Hammer, anvil, stirrup Tempanic membrane to malleus
to the incus then to the stapes Several openings eustachian tube,
oval window, round window, meatus
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Middle cont. Air spaces at posterior surface by temporal bone
Great opportunity for infection! Eustachian tube bone, cartilage,
fibrous tissue lined with mucus membrane Goes down, forward, and in
from the middle ear to nasopharynx This tube allows for pressure
equalization between inner ear and outer surface
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Inner ear Labrynth complicated shape Two main parts bony and
membranous Bony three parts vestibule (contains utricle and
saccule), cochlea (means snail), semicircular canals Membranous
utricle, saccule, cochlear duct, membranous semicircular canals
Vestibule and semicircular canals maintains balance Cochlea hearing
Cochlear nerve (8 th ) extends from the base of the cochlear duct
in the cochlea
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Hearing: Sound comes from vibrations from air, fluid, or solid
material How is sound created through your larynx? Vibrating vocal
cords create sound waves by producing vibrations in air passing
over them Volume refers to amplitude (height of the wave) Pitch
number of waves occuring during a specific time unit (frequency)
Ability to hear depends on volume, pitch, and healthy anatomy and
cerebral cortex reception in the auditory area in the temporal lobe
after going through relay stations in the thalamus, midbrain,
medulla, and pons
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WHAT COULD INTERRUPT THE PROCESS OF HEARING?
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Causes of hearing loss: 2 or 3 out of every 1000 babies are
born deaf or with a major hearing deficit Millions of individuals
are choosing hearing loss due to sound pollution Where do you go
for pollution?
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YOU TUBE VIDEOS: Hearing Cochlear implant
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Balance Vestibule and semicircular canals Static equalibrium
created in utricle and saccule ability to sense position of the
head relative to gravity also acceleration/deceleration Dynamic
equilibrium semicircular canals helps to maintain balance when
sudden movements occur with spinning motion, semicircular canals
move with the body but not at the same rate and the capula moves in
an opposite direction until movement stops
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VERTIGO
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Canalith repositioning procedure:
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Hearing loss Conductive hearing loss transmission Middle ear
infections Glue ear collection of fluid in middle Wax accumulation
Otosclerosis Ossicle damage head trauma, inf. Perforated tempanic
membrane
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Loss cont. Presbycusis loss of hairy cells! Acoustic trauma
Viral or bacterial inf Menieres disease Drugs Acoustic neuroma
benign MS, stroke, tumor Pregnant woman with rubella CMV in
pregnancy
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Testing: Whisper test Tuning fork Pure tone audiometry
Otoacoustic emissions cochlea Auditory brainstem response cochlea
and nerve impulse to the brain MRI Normal 0-20 dB (range of
frequencies) Mild loss - 25-39 dB Moderate loss 40-69 dB Severe
loss 70-94 dB Profound 95 dB or greater
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TMT: Sign language Hearing aids Cochlear implant Lip reading
Surgical excision of tumorous growth
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I see you!!!!! I see you!!!!!
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Structure Three layers: outside in sclera, choroid, retina
Anterior portion cornea (avascular) covers iris transparent, sclera
is opaque Middle choroid vascular pigmented Anterior choroid three
structures ciliary body, suspensory ligament, iris
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Choroid structures Ciliary body fits between the anterior
retina and posterior iris Iris smooth muscle fibers hole in middle
pupil Retina innermost coat of the eyeball (no anterior
portion)
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Conduction of impulses: Photoreceptor neurons Bipolar neurons
Ganglion neurons
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Blind spot No rods and cones present Optic disc (part of
sclera) contains perforations through which fibers emerge from the
eyeball creating the optic nerve Pg 466
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Cavities Anterior two divisions anterior/posterior chambers
Lies in front of the lens Aqueous humor fills both chambers clear,
watery formed from capillaries Posterior larger than anterior
Occupies all space posterior to the lens Vitreous humor semi solid
jello Maintains intraocular pressure to keep eye from collapsing
normal 20-25 mmHg If over, glaucoma