1. Sensory System
Chapter 20

2. Function Environmental Organs
Receptors specializing perceiving change from internal & external environment
Environmental
Vision
Hearing
Touch
Taste
Smell
Pain
Balance
Thirst
Hunger
Organs
Eye
Ear
Tongue
Nose
skin

3. EYES Receive 90% environmental information Blinking-reflex to protect
Conjunctiva-protects & lubricates
Lacrimal duct-tears
1/5th of eye external

5. Eyes Sclera-supports & gives structure Cornea-focuses light to retina
Choroid, iris, & ciliary muscles-provide blood supply
Iris & ciliary muscles-intrinsic muscle
Eyeball
Not solid
Anterior cavity
Clear watery fluid-aqueous humor
Posterior cavity
Semisoft gelatin-vitreous humor
Both cavities help maintain shape

6. Eyes Pupil Iris Lens Black part Round, colored muscle
Contracts/relaxes to allow for light
Lens
Convex, transparent tissue
Focuses & directs light to retina

7. Vision is similar To a camera.
Refraction
Lens bends light to focus on the retina.
Accommodation
lens changes shape focusing near & far.
Converge
Creates one object to see

8. Eyes Rods Cones Sensitive to dim light 100 million rods
Sensitive to bright light
Color distinction
Green
Red
blue
Impulses transmitted to brain by optic nerve

9. Ear Functions Hearing Equilibrium Men listen with left side of brain
Women use both sides.

10. External Ear Pinna Tympanic Membrane Cerumen
Collects & transmits sound waves
Tympanic Membrane
Separates outer & middle ear
AKA eardrum
Cerumen
AKA ear wax
Protects from FB

11. Middle Ear Air filled chamber Bones Eustachian tube Tympanic membrane
Changes sound waves to mechanical movements
Bones
Hammer (malleus)
Anvil (incus)
Stirrup (stapes)
Move to transmit sounds
Eustachian tube
Connect ear with pharynx
Maintains pressure of air of middle ear to environment
Drain fluid & mucus into throat
Swallowing & yawning open Eustachian tube

12. Main component for balance Bony labyrinth-series of canals
Inner ear
Main component for balance
Bony labyrinth-series of canals
Cochlea
Fluid & hair convert mechanical vibration to neural impulses
Semicircular canal
Endolymph-clear fluid maintains equilibrium in motion
Vestibule
maintain static or resting equilibrium

13. Gustatory Taste buds Every person has a unique tongue print.
Specialized papillae cells
Chemoreceptors
Sweet
Salty
Sour
Bitter
Umami-meatiness
Every person has a unique tongue print.
Most people have lost 50% of their taste buds by the time they turn 50.

14. olfactory Scents send to brain through olfactory nerve Septum
Divides into right & left
10,000 times more sensitive than taste
5,000 distinct smells can be detected
mix of 30 primary odors
Primary odors
Floral
Putrid
peppermint
Sense has ability to:
Reduce Stress
Affect Blood pressure
Recall memories
Aid in sense of taste

15. Skin Meissner's corpuscles light touch and motion Pacinian corpuscles
deep pressure
End-bulbs of Krause
cold, low-frequency vibrations, two-point discrimination
Corpuscles of Ruffini
heat, deep pressure, and continuous touch
Nociceptors
Pain receptors
Respond to more than one stimulus

16. visual acuity-snellen chart
Assessment
Sight
Hearing
Ophthalmoscope
visual acuity-snellen chart
Tonometer - measures pressure of the inner eye
Otoscope
Audiometer
Impedance testing measure s flexibility of TM
Rinne’s test -tuning fork assesses transmission of sound through the ear
Weber's test- tuning fork to test for unilateral hearing loss

17. Disorders Achromatism Amblyopia AKA lazy eye poor vision in one eye
AKA color blindness
Amblyopia
AKA lazy eye
poor vision in one eye
Results from better vision in the other eye
Anacusis
Hearing loss from damage to neural tissues

18. Disorders Astigmatism Congenital defect
imperfect curvature of the cornea
Results in blurred vision
Cataract
Clouding of the lens
Conjunctivitis
AKA pink eye
bacterial or viral inflammation of the eyelid.

19. Cataracts

20. Disorders Deafness Complete hearing loss in one or both ears
Inherited
complications at birth
disease
excessive noise
ototoxic drugs
Diabetic retinopathy
damaged blood vessels in the retina caused by uncontrolled DM

21. Cochlear Implant

22. muscle imbalance or paralysis of an extraocular muscle. Epistaxis
Diplopia
AKA double vision
muscle imbalance or paralysis of an extraocular muscle.
Epistaxis
AKA Nosebleed
Disease
Trauma
Hypertension
Leukemia
rheumatic fever
Glaucoma
Increased pressure inside the eye
trauma
hereditary factors

23. Hyperopia Macular degeneration Farsightedness congenital deformity
Slow or sudden, painless loss of central vision

24. Macular Degeneration

25. Collection of fluid in the labyrinth
Ménière's disease
Collection of fluid in the labyrinth
leads to:
dizziness,
ringing in the ear (tinnitus),
Pressure
Deafness
Myopia
Nearsightedness
congenital deformity in the eye
Night blindness
Poor vision in dim light

26. Disorders Otitis media Middle ear infection Presbyopia
bacterial or viral
common in young children
Presbyopia
Type of farsightedness related to aging
Retinal detachment
Result of injury
uncontrolled diabetes mellitus

27. Otitis Media

28. Inflammation of the lining of the nose
Rhinitis
Inflammation of the lining of the nose
causes
allergic reaction
viral infection
Sinusitis
chemical irritants
Ruptured eardrum
infection,
an explosion
a blow to the head
a sharp object inserted into the ear
Chronic or acute inflammation of a sinus

29. Strabismus
both eyes do not focus on the same point or direction
Stye
Bacterial infection of the sebaceous glands of the eyelid