Download Eyes - science105

PowerPoint® Lecture Slide Presentation
by Patty Bostwick-Taylor,
Florence-Darlington Technical College
Special Senses:
Eyes
8
PART A
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 Choroid – Skinlike
 Photo - Light
 Iris – Rainbow
 Rectus - Straight
 Lacri – Tears
 Scler – Hard
 Macula – Spot
 Vitre - Glass
 Oc- Eye
 Orbi - Circle
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The Eye and Vision
Protection for the eye
 Most of the eye is enclosed in a bony orbit
 A cushion of fat surrounds most of the eye
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Accessory Structures of the Eye
 Eyelids and eyelashes
 Conjunctiva
 Lacrimal apparatus
 Extrinsic eye muscles
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Accessory Structures of the Eye
Figure 8.1
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Accessory Structures of the Eye
 Conjunctiva
 Membrane that lines the eyelids
 Connects to the surface of the eye
 Secretes mucus to lubricate the eye
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Accessory Structures of the Eye
 Lacrimal apparatus
 Lacrimal gland—produces lacrimal fluid
 Lacrimal canals—drain lacrimal fluid from
eyes
 Lacrimal sac—provides passage of lacrimal
fluid towards nasal cavity
 Nasolacrimal duct—empties lacrimal fluid into
the nasal cavity
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Accessory Structures of the Eye
Figure 8.2a
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Accessory Structures of the Eye
Figure 8.2b
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Accessory Structures of the Eye
 Function of the lacrimal apparatus
 Protects, moistens, and lubricates the eye
 Empties into the nasal cavity
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Accessory Structures of the Eye
 Properties of lacrimal fluid
 Dilute salt solution (tears)
 Contains antibodies and lysozyme
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Accessory Structures of the Eye
 Muscles of the eyelids
 Orbicularis oculi – closes eye
 Levator palpebrae superioris – opens eye
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Accessory Structures of the Eye
 Extrinsic eye muscles
 Six muscles attach to the outer surface of the
eye
 Superior rectus
 Inferior rectus
 Medial rectus
 Lateral rectus
 Superior oblique
 Inferior oblique
 Produce eye movements
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Accessory Structures of the Eye
Figure 8.3a–b
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Accessory Structures of the Eye
Figure 8.3c
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DCL #10
 Draw Color and Label Figure 10.15 and 10.16
 Also label the Conjunctiva and Orbicularis oculi
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Structure of the Eye
 Layers forming the wall of the eyeball
 Fibrous layer
 Outer Tunic
 Vascular layer
 Middle Tunic
 Sensory layer
 Inner Tunic
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Structure of the Eye
Figure 8.4a
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Structure of the Eye
Figure 8.4b
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Structure of the Eye: The Fibrous Layer (Outer)
 Sclera
 Connective tissue layer (protection)
 The “white of the eye”
 Cornea
 Transparent
 Window that focuses light rays
 No blood vessels, transplants easily
 Optic Nerve
 Sends signals to brain
 Blood vessels attach there
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Structure of the Eye: Vascular Layer (Middle)
 Choroid coat
 Rear 5/6 of eye containing blood vessels
 Melanin for light absorption
 Ciliary body—smooth muscle attached to lens
 Lens - central clear body, can change shape
 Accomodation - thickening or thinning of the
lens for distance sighting
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Structure of the Eye: Vascular Layer (Middle)
 Iris
 Regulates amount of light entering eye
(opening and closing the pupil)
 Colored portion of the eye
 Aqueous humor
 Fluid secreted from ciliary body
 Pupil
 Rounded opening in the center of the iris
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Structure of the Eye: Sensory Layer (Inner)
 Retina
 Contains receptor cells (photoreceptors)
 Rods
 Cones
 Optic disc
 Blind spot
 Vitreous humor
 Jellylike fluid that fills the inside of the eye
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DCL #11
 Draw Color and Label Figure 10.17
 Label ALL from text
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Structure of the Eye: Sensory Layer
 Signals pass from photoreceptors through
neurons
 Signals leave the retina through the optic nerve
 Optic disc (blind spot) is where the optic nerve
leaves the eyeball
 Cannot see images focused on the optic disc
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Structure of the Eye: Sensory Layer
Figure 8.5a
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Structure of the Eye: Sensory Layer
Figure 8.5b
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Structure of the Eye: Sensory Layer
Rods
 Dim light vision and peripheral vision
 All perception is in gray tones
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Structure of the Eye: Sensory Layer
Cones
 Allow for detailed color vision
 Fovea centralis—area of the retina with only
cones
 No photoreceptor cells are at the optic disc, or
blind spot
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Ophthalmoscope
 Instrument used to illuminate the interior of the
eyeball
 Can detect diabetes, arteriosclerosis,
degeneration of the optic nerve and retina
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Posterior Wall of Retina
as Seen with Ophthalmoscope
Figure 8.8
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Pathway of Light Through the Eye
 Light must be focused to a point on the retina for
optimal vision
 The eye is set for distance vision
(over 20 feet away)
 Accommodation—the lens must change shape to
focus on closer objects (less than 20 feet away)
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Pathway of Light Through the Eye
Figure 8.9
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Pathway of Light Through the Eye
 Image formed on the retina is a real image
 Real images are
 Reversed from left to right
 Upside down
 Smaller than the object
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Images Formed on the Retina
Figure 8.10
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Visual Fields and Visual Pathways
Figure 8.11
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EYE CONDITIONS
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Lens
 Cataracts result when the lens becomes hard and
opaque with age
 Vision becomes hazy
 Eventually causes blindness
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Lens
Figure 8.7
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A Closer Look
Myopia (nearsighted)
 Distant objects appear blurry
 Light from those objects fails to reach the
retina and are focused in front of it
 Results from an eyeball that is too long
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A Closer Look
 Hyperopia (farsighted)
 Near objects are blurry while distant objects
are clear
 Distant objects are focused behind the retina
 Results from an eyeball that is too short or
from a “lazy lens”
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A Closer Look
 Astigmatism
 Images are blurry
 Results from light focusing as lines, not
points, on the retina due to unequal
curvatures of the cornea or lens
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Homeostatic Imbalances of the Eyes
 Night blindness—inhibited rod function that
hinders the ability to see at night
 Color blindness—genetic conditions that result in
the inability to see certain colors
 Due to the lack of one type of cone (partial
color blindness)
 Cataracts—when lens becomes hard and opaque,
our vision becomes hazy and distorted
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Homeostatic Imbalances of the Eyes
 Glaucoma—can cause blindness due to
increasing pressure within the eye
 Hemianopia—loss of the same side of the visual
field of both eyes; results from damage to the
visual cortex on one side only
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