Transcript Unit 8: The Senses

Unit 8: The Senses
The Senses DB
• Explain why the smell of a doctor�s office or the smell
of turkey cooking on Thanksgiving can easily generate
an emotional response. Hint: there is a concept called
sense memory that should be referenced here.
OR
The ear is important in not only hearing, but balance.
Explain how the ear functions, and how it can be easily
damaged by loud noises, and result in hearing loss.
OR
How do we perceive color? Why does the color wash out
when we look at a bright light, or are out in the sun?
Responsibilites for the week
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Work on APT project. Writing paper!! 
Lesson 1: Sense Organs
Lesson 2: The Eye
Lesson 3: The Ear
The Senses: Quick Wrap-Up
Unit 8 Practice Quiz
Discussion
Seminar
The Senses Module Exam
LEARNING OUTCOMES
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HS120-U8-1
general.
Classify sense organs as special or
HS120-U8-2 Describe the general sense organs and
their functions.
HS120-U8-3
eye.
Identify the structures and functions of the
HS120-U8-4
Identify the structures functions of the ear.
HS120-U8-5
Discuss the physiology of hearing.
Classify sense organs as special or
general
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Special:
Eye
Taste buds
Ear
Nose
• General:
• Microscopic receptors
– Pacinian corpuscles
– Meissner’s corpuscles
– Muscle spindles
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• What is the difference between
special and general sense
organs?
The differences
• Special = they have large and complex
organs or localized groupings of
specialized receptors like taste buds on
tongue.
• These are the senses that you typically
think of; except for perhaps touch!
A very special sense
The differences
• General = made of microscopic receptors
widely distributed throughout the body.
– Pacinian corpuscles = pressure and high
frequency
– Meissner’s corpuscles = fine touch and low
frequency
– Muscle spindles = propriocetors (muscle
length and location)
Sense organ functions
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Vision
Hearing
Smell
Taste
Balance
How is a stimulus converted into a
sensation?
Stimulus detected
[sound]
Stimulus converted to
electrical signal or nerve
impulse= [middle ear]
Signal transmitted over
nervous system “pathway”
= [VIII cranial nerve]
Sensation perceived
in brain = [music]
music
Sound is:
A pressure
disturbance
(alternating areas
of high and low
pressure)
originating from a
vibrating object
Eye anatomy
• Sclera = white of the eye (cornea)
• Choroid = contains a dark pigment to prevent scattering
of light rays
• Retina = innermost layer of eyeball (rods and comes)
• Iris = circular colored part of eye
• Conjunctiva = mucous membrane that lines eyelids and
covers the sclera
• Lacrimal gland = tear duct
• Pupil = black center of iris; a hole
• Lens = ciliary muscles contract the lens for focusing
Posterior wall right eye
of
Rods only
Less cones
cones
Macula Lutea
Mostly Cones
Fovea
Centralis
ONLY Cones
Detailed color
vision
cones
Pg
56
3
Optic
Disc
Lateral
to ML.
Radiate
s Blood
V.
The Retina: Photoreceptors
• Rods:
– Respond to dim light
– Are used for peripheral vision
– Ex. Best to see moonlit evening when you don’t look
directly at object. Recognize best when they move.
Peripheral.
• Cones:
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Respond to bright light
Have high-acuity color vision
Are found in the macula lutea
Are concentrated in the fovea centralis
The Retina: Ganglion Cells and
the Optic Disc
Focusing Light on the Retina;
Pathway of light entering the eye:
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Light is Refracted
cornea
Refracted again
aqueous humor
Lens
Refracted again
vitreous humor
the neural layer of the retina to the
photoreceptors
Major visual disorders
• Refraction disorders
– Myopia = nearsightedness
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Astigmatism = irregularity in cornea or lens
Conjunctivitis = pink eye
Strabismus = convergent
Cataracts=?
Macular Degeneration=?
Glaucoma=?
Eye anatomy
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Sclera
Choroid
Retina
Iris
Conjunctiva
Lacrimal gland
Pupil
Lens
Ciliary Muscles
Ear anatomy
• External ear
– External auditory canal
– Tympanic membrane
– eardrum
Ear anatomy
• Middle ear
– Ear bones = ossicles
• Malleus
• Incus
• stapes
– Auditory or Eustachian tube
Ear anatomy
• Inner ear
– Bony labrinth
– Perilymph
– Vestibule
– Semicircular canals
– Cochlea
– Crista ampullaris
– Organ of Corti
PATH: Transmission of Sound to
the Inner Ear
Sound and Mechanisms of
Hearing
• Sound vibrations beat against the eardrum
• The eardrum pushes against the ossicles,
which presses fluid in the inner ear against
the oval and round windows
– This movement sets up shearing forces that
pull on hair cells
– Moving hair cells stimulates the cochlear
nerve that sends impulses to the brain
Deafness
• Conduction deafness – something
hampers sound conduction to the fluids of
the inner ear (e.g., impacted earwax,
perforated eardrum, osteosclerosis of the
ossicles)
• Sensorineural deafness – results from
damage to the neural structures at any
point from the cochlear hair cells to the
auditory cortical cells
Hearing impairment
• Blockage of external auditory canal
• Otosclerosis = structural irregularities in
stapes
• Tinnitus = ringing in ears (may be
symptom of otosclerosis)
• Otitis = ear infection
• Meniere’s disease = chronic inner ear
disease, resulting in vertigo
areas for taste receptors
Sour Bitter
POSTERIOR
TONGUE
Sour Bitter
Sour Bitter
salty
salty
salty
salty
salty
Sweet -tip
ANTERIOR
TONGUE
salty
Taste Sensations
• There are five basic taste sensations
– Sweet – sugars, saccharin, alcohol, and
some amino acids
– Salt – metal ions
– Sour – hydrogen ions
– Bitter – alkaloids such as quinine and
nicotine
– Umami – elicited by the amino acid
glutamate
Influence of Other Sensations
on Taste
• Taste is 80% smell
• Thermoreceptors, mechanoreceptors,
nociceptors also influence tastes
• Temperature and texture enhance or
detract from taste
Which one would be
the worst to lose?
• Have you any
questions? Do you
have any questions?
Are there any
questions? Can I
answer anything?
Can I answer
anything for anybody?
Is anything unclear?
Is everything clear?