Transcript Middle Ear

Week #6 (2/8 – 2/12)
Warm Up – Mon, 2/8:
-Special Senses Latin Cards
Anatomy Fun Fact:
In 1 min, the brain will
consume 46 cm3 (1/5 cup)
of oxygen from blood. Of
that oxygen consumed, 6%
will be used by the brain's
white matter & 94% by the
grey matter. The brain can
stay alive for 4-6 mins
without oxygen; after that
cells begin die.
Agenda:
1. Special Senses Latin cards
2. Begin Special Senses - Eye
Have out:
Index Cards
Pick up:
1 colored marker
6 index cards & a
scissors
Diagram of the Eye
Homework:
1.
2.
Special Senses
Latin Cards –
Tues, 2/9
Brain/Spinal Cord
Dissection
Abstract (1D) –
Wed, 2/10 &
Thurs, 2/11
Nervous System (Special Senses)
Latin Roots
• Glauc(o) – bluish-gray color
• Photo – light
• -oma – tumor
• Recepto- – receive
• Audire – to hear
• Conjunctiva – connective
• Auri – ear
• Lacrima – tear, weeping
• Helix – spiral
• Vascu – made of vessels
• Tympani – small drum
• Sclera – outermost coat of eye
• Oss – bone
• Cornea – resembling a horn in hardness &
appearance
• Malleus – hammer, mallet
• Choroid – skin-like
• Retina – interior, light-detecting coat of eye
• Humor – fluid, liquid
• Vitreo – glass-like, glaze
• Aque/a – water
• Iris – rainbow
• Incus – anvil
• Stapes – stirrup
• Vestibul(um/i) – entrance
• Semi – half
• Cochlea – snail shell-shape, spiral in
shape
Taste, Smell, Sight, Hearing
(we’re just going to focus on “Sight & Hearing”)
• Photoreceptors – visual
receptor cells
• Adult eye = ~ 1 in.
diameter
• Accessory structures –
protect the eye or aid in its
functioning
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Eyebrows
Eyelids
Conjunctiva
Lacrimal apparatus
Extrinsic Eye muscles
Eyebrows & Eyelids
• Eyebrows
• Shade eyes from sunlight
• Prevent perspiration from
entering eyes
• Eyelids (palpabrae)
• Blinking occurs every 3-7
secs to prevent dehydration
of eyes
• Eyelashes are richly
innervated, so anything that
touches them, including a
puff of air, triggers reflex
blinking
Conjunctiva
• Transparent mucous membrane
that lines eyelids & reflects over
surface of eyeball
• Lubricate eye & to prevent
invasion to posterior portion of
eye
• Conjunctivitis is an
inflammation of the
conjunctiva
• Pinkeye is a type of conjunctivitis
caused by bacteria or virus
Lacrimal Apparatus
• Consists of the lacrimal
gland & lacrimal
ducts
• Lacrimal gland releases
fluid that is spread over
eye when blinking
• Contains mucus,
antibodies & lysozyme
(a bacteria-destroying
enzyme)
Don’t need
to know this!
Don’t need to know this!
Structure of the Eyeball
• Made up of three layers called tunics
• Fibrous (1)
• Vascular (2)
• Sensory (3)
• Fibrous tunic is the outermost coat of the eye (1)
• Divided into 2 major
regions: sclera & cornea
• Sclera (tough connective tissue) “whites of the eye”
• Functions to protect & shape
eyeball
• Sturdy anchoring for extrinsic
eye muscles
3
More on the Eye
• Cornea - anterior 6th of fibrous tunic
• Covered on both sides by simple
squamous epithelium
• Lined with pain fibers (which is why
contacts can be so tough to adjust to)
• When cornea is touched, reflex blinking & increased lacrimal
fluid secretion occur
• FUN FACT:
• Since cornea has no blood supply it is the only tissue that can
be transplanted with very little fear of rejection (does not have
contact with immune system)
Week #6 (2/8 – 2/12)
Warm Up – Tues, 2/9:
- Intro to NS Review
Pick up:
3 colored pencils
Brain Latin Takehome Quiz
Anatomy Fun Fact:
Results from cognitive tests show 30% of 80year-olds perform as well as young adults
(like YOU!).
Homework:
1.
2.
Agenda:
1.
Finish Eye/Vision notes
3.
Brain/Spinal Cord
Dissection
Abstract (1D) –
Wed, 2/10 &
Thurs, 2/11
Brain Latin Takehome Quiz – Fri,
2/12
Nervous System
Exam – Fri, 2/19
Iris
• Most anterior part of vascular
tunic (middle layer) (2)
• Between cornea & lens
• Round central opening (pupil)
allows light to enter eye
• Made of smooth muscle fibers
that contract & dilate
depending on light stimulus
3
Iris
• Though it seems to appear in many colors (Iris means
“rainbow”), it actually only contains brown pigment
• When an iris contains a lot of pigment, the eyes appear
brown or black
• If the amount of pigment is
small, the short wavelengths
of light are scattered from
the unpigmented parts of the
iris & eyes appear blue,
green, or gray
• Why, then, do newborn
babies often appear to
have gray or blue eyes?
The Sensory Tunic (Retina & Lens)
Lens
• Deepest layer
• Contains the lens (hard disc) which allows
an image that is upside down & backwards
• Has pigmented cells that absorb light
• Stores Vitamin A, which is needed by
photoreceptor cells
• Contains millions of photoreceptors
• Rods & cones
• Rods - more numerous & are our
dim-light & peripheral receptors (more
sensitive to light)
• Cones - bright light & provide highacuity color vision
• The optic disc (located where the optic
nerve leaves the posterior portion of the
eye) is called the “blind spot” because it
contains no photoreceptors
Internal Chambers
• Filled with aqueous humor
which is produced in posterior
chamber & drains from
anterior chamber
• If drainage is blocked, pressure
within eye may increase &
cause compression of retina &
optic nerve condition called
glaucoma
• Exam to diagnose is simple…a
puff of air at the sclera will
produce a measurable amount
of deformation
Colorblind &
blindspot Tests
• Colorblindness:
• http://www.toledo-bend.com/colorblind/Ishihara.html
• http://colorvisiontesting.com/online%20test.htm#demo
nstration%20card
• Blind Spot:
• http://faculty.washington.edu/chudler/chvision.html
Week #6 (2/8 – 2/12)
Warm Up – Wed, 2/10 & Thurs,2/11:
Turn in:
Anatomy Fun Fact: How does Lasik surgery
correct/improve vision?
Pick up:
- Structure of the Eye wkst
The surgeon uses a small instrument, called a
microkeratome, to create an ultra-thin flap in the
cornea. After the surgeon
has created a flap, they will
use an excimer laser to
reshape the corneal tissue.
It is this reshaping of the
cornea that improves your
vision, changing the way
your eye focuses light.
Agenda:
1. Cow Eye Dissection
2. Discuss Eye Dissection Lab Abstract
Brain/Spinal Cord
Dissection Abstract
(1D)
Structure of the
Eye wkst
Homework:
1.
Brain Latin Takehome Quiz – Fri,
2/12
2. Cow Eye
Dissection (2D)–
Fri, 2/19
3. Nervous System
Exam – Fri, 2/19
Cow Eye Dissection (2D)
• Follow the directions CAREFULLY off of
the “Cow’s Eye Dissection” packet.
• On a separate piece of paper (with ALL
GROUP MEMBERS’ names), answer the
questions in your Nasco Lab Manual
(Conclusion & Application section)!
• Only take enough gloves for those who
will be dissecting/holding eye.
• Make sure to CLEAN & DRY lab stations,
kits & trays after you are finished!
• Have fun!
Eye Dissection Lab Abstract (2D)
DUE: Fri, 2/19
• Title Page: Title of Lab, Name, Date, Period
• Data & Observations:
• Pictures of Eye (whole & internal structures) w/correct identifications
• Conclusions & Applications:
• Answers to ALL questions from Lab Manual (in paragraph form)
• Discuss the cause(s) of the disease, symptoms, treatments or cures & what
structures/regions of the eye are degenerated/damaged due to the disease
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What is the function of eyelids? Eyelashes? Eyebrows?
Of what biological use are tears to the eye?
Of what value is the response of pupil dilation & constriction?
Describe the function for each of the pairs of muscles that are attached to the eye.
What is the relationship of the optic nerve & the brain?
What type of muscle orientation in the iris would be necessary to regulate the diameter of the pupil?
What is the function of the gelatinous substance known as vitreous humor?
• Application: Case Study – research & discuss one disease that affects the eye(s)
• Works Cited (MLA format)
Week #6 (2/8 – 2/12)
Warm Up – Fri, 2/12:
-Sensory Systems Active Reading wkst
Anatomy Fun Fact:
There are over 90% of
deaf children born from
parents with normal
hearing, meaning that a
couple with normal
hearing has no guarantee
that their children will
have normal hearing.
Agenda:
1. Sense of Hearing/Ear notes
2. Work on Nervous System Review Guide
(if time)
Turn in:
Brain Latin Quiz
Pick up:
Sensory Systems
Active Reading wkst
3 colored pencils
Nervous System
Review Guide
Homework:
1.
Cow Eye
Dissection (2D) –
Fri, 2/19
2. Nervous System
Exam – Fri, 2/19
• Divided into 3
major regions:
• Inner ear
• Middle ear
• Outer ear
LABEL & COLOR-CODE YOUR WKST
Outer Ear
•
Middle Ear
Inner Ear
Outer Ear
• Consists of the auricle & the
external auditory canal
• Auricle
• helix (rigid portion)
• lobule (no cartilage)
• Functions to direct sound waves into
external auditory canal
• External auditory canal
• Short (~2.5 cm) & curved
• Extends to the tympanic membrane
(“eardrum”)
Middle Ear
• Small, air-filled cavity
within the temporal
bone
• Eustachian tube
links middle ear to
superior-most part of
the throat
• Normally this is
closed, but yawning
& swallowing opens
this tube briefly to
equalize pressure
Middle Ear
• Contains the 3 smallest bones in
the body: the ossicles
• Malleus – secured to the
tympanic membrane
• Incus
• Stapes – connects to the inner
ear (via the oval window)
• Tensor tympani muscle attaches
auditory tube (Eustachian tube) to
malleus
• This muscle helps prevent
damage to inner ear under
extremely loud conditions
Inner Ear
• Located deep within
the temporal bone &
posterior to the eye
socket
• Made up of the
vestibule, semicircular
canals & cochlea
Vestibule
• Central egg-shaped cavity that medially borders the
middle ear
• Contains perilymph
(similar to CSF)
• Houses equilibrium
censors called maculae
that respond to pull of
gravity & report changes
of head position
Semicircular Canals
• Made up of an
anterior, posterior, &
lateral canals
• Have receptors to
help with equilibrium
Cochlea
• About 1/2 size of a pea
• Contains 3 hollow cavities
• Cochlear duct contains spiral
organ of Corti – receptor
organ for hearing
• Cochlear nerve runs from the
spiral organ of Corti to the
brain
Hair Cells
in the
Spiral Organ
of Corti
• Roughly 16,000
hearing receptor cells
called cochlear hair
cells line the spiral
organ of Corti
• Sounds set up vibrations in air that beat against the
ear drum
• This pushes the ossicles that press fluid in the inner
ear against membranes
• This pressure on the membranes pulls on tiny hair
cells that stimulate nearby neurons that give rise to
impulses that travels to the brain, where they are
interpreted
Deafness
• 2 types:
• Conduction
• Sensorineural
• Conduction deafness –
when something
interferes with
conduction of sound
vibrations to the fluids
of the inner ear
occurs
Deafness
• 2 types:
• Conduction
• Sensorineural
• Sensorineural deafness – results
from damage to neural structures
at any point in the hearing pathway
• This typically results from the gradual loss of
hearing receptor cells:
• Throughout life
• Single explosively loud noise
• Prolonged exposure to high-intensity sounds, which
cause these cells to stiffen