Unit 8 Special Senses

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Unit 8 Special Senses
HS 62 Your Living Body
Tim Baylink, MD Adjunct Professor Anatomy
Physiology Health Sciences Department
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Unit 8Special Senses
Smell
Sight
Balance
Sound
Taste
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Special Senses

• Sight
• ? Processed in the Retina a posterior eye
  membrane made of nerves (rods cones). Cones
  Process Color and Rods Process Black White.
• Sound
• ?Sound Waves/Vibrations are converted to Nerve
  Impulses and processed by the Brain as Sound.
• Touch (Balance)
• ? The Inner Ear houses the structures that
  maintain balance and hearing. The Brain detects
  the movement of Otoliths during positional
  changes.
• Smell
• ?Via the Nostrils Mouth, Olfactory signals are
  sent to the Brain through the Cribiform Plate of
  the Ethmoid Bone.
• Taste
• ?Signals generated from several areas on surface
  of the Tongue.

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Special SensesProcessed in the Cerebral Cortex
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Eye Surface Anatomy
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The Nasolacrimal Duct
Why do yet a runny nose when your eyes water?
Which eye is this?
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Eye Anatomy
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Anatomy of the Eye
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VisionUpside Down Backwards
Images are converted back to normal in the
Occipital Lobe. Where is the occipital lobe?
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Vision
- initially processed upside down backwards -
the brain wrights the object in the occipital lobe
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Retina Rods Night Peripheral Vision Cones
Color Vision, Bright LightWhy do some pupils
appear red in photographs?Does the flash have to
be on to do this?
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Ocular Diseases
Corneal Abrasions
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ConjunctivitisPinkeye

• Viral or Bacterial
• ? Difficult to tell apart
• All Patients Rx Abx Drops
• Highly contagious
• Nasolacrimal Duct Massage

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What is this?
Opacity of the Lens
Ophthalmoscope Exam
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CataractsLens Opacities
Chronic exposure to ultraviolet light is
implicated in cataract formation
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CataractsTreatment
When in doubt, Cut it out.
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GlaucomaIncreased intra-ocular Pressure
? ? Pressure leads to damage to optic nerve ?
Causes bilateral loss of vision ? Begins with a
decrease in peripheral vision ? Leads to
central vision loss blindness ? The leading
cause of irreversible blindness
The anterior chamber is filled with aqueous
humor, which provides nourishment to the
structures in the front of the eye. AH is
produced constantly by the ciliary process which
surrounds the lens of the eye. AH then flows
through the pupil and leaves the eye through tiny
channels called trabecular meshwork.
Obstruction ? IOP Glaucoma.
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Prosthesis vs. Organ DonationAnd the Eye
Corneal Transplant There has been no success in
prosthetics The only source is via
transplantation People are blind without the
cornea
Ocular Lens Prosthesis We can fabricate an
adequate replacement
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Funduscopic Exam

• Retinal Hemorrhages
• Severe trauma
• Repetitive assaults
• Shaken Babies
• Bleeding Disorders

Normal Fundus
19 year old male patient who was struck on the
head by a baseball bat. The patient is
unresponsive, has snoring respirations and can
not be roused. VS BP 168/90 P 56 R 14. Pt. is
intubated, Pupils are equal at 4 mm, right pupil
not reactive to light. Funduscopic exam of the
Right eye is shown above.
Papilledema - Edema of the optic disk due to
increased intracranial pressure
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Diabetic Retinopathy DM is a Micro-Vascular
Disease

• Neovascularization
• Hemorrhages
• Aneurysms
• Plaques

Classic DM Retinopathy
s/p Laser Ablation
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Ocular Trauma
Scleral Hemorrhages - only look bad
Enucleate To remove entirely to shell like a
nut, as in the removal of an eye from its capsule
or a tumor from its compressed surrounding tissue.
Never remove an Impaled Object from the eye.
Fluid loss can destroy eye.
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quit squirming around, kid.
A boy rubs his eye too hard and it swells up
He visits the doctor who says he has an abscess
that needs an I D.
So, an appointment is scheduled
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Hey, thats not an Abscess
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Is that a Worm?
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A Human Botfly Larvae
The above represents a human botfly larva from
the eye socket of a 5-year old boy in Honduras.
The article asserts that such infestation is
extremely rare, relatively harmless and easily
extracted.
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Hearing and BalanceThe Ear
Three Sections 1) External Ear 2) Middle Ear 3)
Inner Ear
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Hearing

• The only purely Mechanical Sensation
• The other SS each have a chemical component

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Sound Waves in the Ear
The Malleus, the hammer The Incus, the anvil
The Stapes, the stirrup
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The Process of Sound
Semicircular canal
Stapes
Oval window
Auditory nerve
Incus
Malleus
Round window
Cochlea
Ear drum (tympanic membrane)
Eustachian tube
Sound
Ear canal
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Hearing BalanceThe Inner Ear
Hearing Cochlea The cochlea consists of a spiral
canal making two and a half turns around a
central core. Longer sound waves progress deeper
and stimulate deeper nerves, creating the
detection of lower notes in the brain. Balance
Semicircular Canals The Brain detects the
movement of otoliths during positional changes.
These signals allow the brain to accommodate for
positional changes. What is an example where
this system is overloaded and problems arise?
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Hearing
Cochlea Short, high frequency (high tones)
intersect earlier in the tube systems. Those
nerves transfer a high pitch message to the
brain. Longer sound waves progress deeper and
stimulate deeper nerves, creating a the detection
of a lower note in the brain.
http//www.blackwellpublishing.com/matthews/ear.ht
ml
http//www.physpharm.fmd.uwo.ca/undergrad/medsweb/
L4Aud/m4aud.swf
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Semi-Circular CanalsBalance
Semi-circular Canals Three bony tubes lie in
planes at right angles to each other and are
known as the semicircular canals. Maintain
Balance This is done by the Brains detection of
the movement of otoliths during positional
changes. These signals allow the brain to
accommodate for positional changes.
http//www.bbc.co.uk/science/humanbody/body/factfi
les/balance/balance_ani_f5.swf
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Semicircular canals
Utricle
Saccule
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TasteGustatory Sensation
http//www.bbc.co.uk/science/humanbody/body/factfi
les/taste/taste_ani_f5.swf
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OlfactionSense of Smell
Cranial Nerve I, The Olfactory Nerve is
responsible entirely for the sense of smell
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Olfaction
Particles enter airways and stimulate olfactory
hair cells that hang down from the olfactory bulb
through the cribiform plate of the Ethmoid bone.
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OlfactionNasal Oral Pathways
http//www.bbc.co.uk/science/humanbody/body/factfi
les/smell/smell_ani_f5.swf