College Knowledge
College adds over $1Million to your lifetime
family income…
But only if you grow up now to take
advantage of this opportunity!
Your Middle and High School teachers are
there to help you open this door…
You need to accept their help!
Heed their advice!
If it is to be, it is up to me!
I’m
Ross Koning
Professor of Biology
at
Eastern Connecticut
State University
Biology Department
PhD 1981
University of Michigan
I teach the introductory biology
course for biology majors here.
Notice, like you, I have
TWO EYES!
Are they identical?
Use both eyes…at arm’s length, center target within finger OK sign
Lock hand in position…see which eye is still aligned by closing the other
The eye with good alignment is your dominant eye!
http://www.twohotpotatoes.com/wpcontent/uploads/whose-plate-4-tips-table-manner-03af.jpg
Figure 46-7
Insects appear to have two eyes also, but they are compound!
Each ommatidium sends separate information to their brain.
Ommatidia are the functional units of insect eyes.
Ommatidia
Ommatidia contain receptor
cells that send axons to the CNS.
Lens
Receptor
cells
Axons
Copyright Norton Presentation Manager
Human vs Insect Vision
Spiders have up to 8 eyes looking in different directions!!
It makes
you
wonder
what
exactly
they see!
http://farm5.static.flickr.com/4010/4682587135_b91e399914.jpg
Copyright Norton Presentation Manager
Vertebrate Eye
senses
image
focuses
image
blind spot
What?
controls light
sends image to brain
Use right eye only (close left eye)…focus only on the target for this test!
Lock head in position…hold one finger up at arm’s length to cover view of target
Move arm slowly outwards from target (to right for right eye)
Find your blind spot for that eye…is it only off to ONE side? try the other side!
Does the blind spot extend upwards or downwards?
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Try with your left eye…is its blind spot on the same side or on the other?
Try with BOTH eyes open…do you have a blind spot now? Why not?
Use right eye only (close left eye)…our target is a row of numbers
1 2 3 4 5 6 7 8 9
Focus on each number in turn, until the break in the blue lines is in your
blind spot. What is different when the blind spot holds a blank area?
blind spot
Figure 46-8
The structure of the vertebrate eye.
In the retina, cells are arranged in layers.
Ganglion cells
Sclera
Iris
Retina
Direction of light
Pupil
Cornea
Fovea
Lens
Optic nerve
(to brain)
Axons to optic nerve
Connecting neurons
Pigmented
Photoreceptor cells epithelium
Figure 46-9
The Cephalopod Eye
Cornea
Lens
Retina
(photoreceptors
are on the inside
surface)
Sensory
nerves to
brain
This “design” is “more intelligent” than that of mammals (humans)
because it lacks the blind spot and maximizes light exposure to receptors
http://upload.wikimedia.org/wikipedia/commons/thumb/b/b6/Diagram_of_eye_evolution.svg/350px-Diagram_of_eye_evolution.svg.png
Eye Evolution
Vertebrate Retina
rod
cone
light
Figure 46-10
Rods and cones contain stacks of membranes.
Rhodopsin is a transmembrane protein complex.
Opsin
(protein
component)
Cone
Retinal
(pigment)
0.5 µm
Rod
Light
Rhodopsin
Light
The retinal molecule inside rhodopsin changes shape when retinal absorbs light.
trans conformation
(activated)
cis conformation
(inactive)
Opsin
Opsin
Light
Use both eyes, stare at area shown in blue for 15 seconds or so
What do you see on this blank white slide? Blink if needed!
This is called an “after image”
Does it move around as you move your gaze?
Light: An Energy Waveform With Particle Properties Too
wavelength
visible spectrum
400
500
600
wavelength (nm)
700 nm
10-9 meter
0.000000001 meter!
Vertebrate Retina
rod
cone
light
Figure 46-13
Visible spectrum
S opsin
420
M opsin L opsin
530
560
Use both eyes, stare at the parrot’s eye for 15 seconds or so
What color is the bird in the cage?
Blink if needed
Use both eyes, stare at the parrot’s eye for 15 seconds or so
What color is the bird in the cage?
Blink if needed
Use both eyes, stare at the parrot’s eye for 20 seconds or so
What color is the bird in the cage?
This color is a bit harder to visualize
Use both eyes, stare at the white dot for 20 seconds or so
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