Sensory organs

1
Sensory organs

• Light rays, sound waves, heat, chemicals, or
  pressure that come into your personal
  territorystimulate your sense organs.

2
(No Transcript)
3
Vision-notes

• a. Light energy enters your eye, and the cornea
  and lens focus it onto the retina.
• b. The light stimulates the rods and cones, two
  types of cells found in your retina.
• c. The rods and cones send impulses to the optic
  nerve, which carries them to the visual area of
  the cortex.
• d. Your cortex interprets the image and you see.

4

• e. Nearsightedness occurs when light is focused
  in front of the retina.
• f. Farsightedness occurs when light is focused
  behind the retina.
• g. Concave lens, thicker at edge than in middle,
  corrects nearsightedness.
• h. Convex lens, thicker in middle than at edge,
  corrects farsightedness.

5
Form a small hole with your hand and move it
vigorously across your line of sight while
focusing on this white screen
6
(No Transcript)
7
Eyes on the Move

• An interesting way to observe the effect that
  drifts, along with associated saccades, have on
  your visual system is to carefully study the type
  of graphic shown here. This experiment will show
  you that your eyes are indeed moving all the
  time, even when you think that they are not.
• Look intently at the center of the following
  graphic. You should see a slight 'shimmering,
  psychedelic effect' that seems to jump about no
  matter how hard you work at holding your eyes
  still. This phenomenon can be enhanced if, while
  you stare at the figure, you stand at arm's
  length, then twist or turn your body. Each time a
  random drift or small saccade takes place, the
  new picture your retina sees appears to interplay
  or interfere with a lingering 'after image' of
  what was seen a fraction of a second earlier.
  That is what causes the appearance of a shifting
  motion within the graphic. In this experiment,
  the tremors are too small and too fast to have a
  noticeable effect.

http//www.creationontheweb.com/content/view/932/
8
(No Transcript)
9
Interesting points!

• Pupil really part of your brain!
• Explaining the eye is a big problem for evolution
• Retina sensitive to 1 photon of light! (cant
  improve on this resolution)
• Photoreceptor cells face away from the light in
  all mammals! why (rods and cones)

10
(No Transcript)
11
Photo cells face away from the light in all
mammals! (rods and cones)

• Why?
• The ends of these cells shed and have to be
  replaced every 7 days
• Besides, these photoreceptor cells have to have
  access to a huge source of bloodso, of all the
  blood in our eye, we only have to see through 5
  (whereas, if the photoreceptors faced out, then
  we would have to see through 95 blood)

12
Lecture slide from The Seeing Eye by Dr. Menton
13
Eye Tricks

• Eye staring contest, eye turn, use small light
  to see dilation

14
Rods and Cones

• The eye is made of cells that are called Rods and
  Cones. Cone cells are coned shaped and Rod cells
  are rod shaped.

• Rods cells have monochromatic vision and Cone
  cells have trichromatic vision. Cone cells see in
  bright light and Rod cells see in black and white
  and in dark light. There are three different
  coloured Cone cells. These are red, green and
  blue. There are an equal amount of coloured Cone
  cells in the eye. The Cone cells are all situated
  at the fovea.

15
Optical illusions
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
(No Transcript)
28
(No Transcript)
29
(No Transcript)
30
(No Transcript)
31
(No Transcript)
32
(No Transcript)
33
(No Transcript)
34
(No Transcript)
35
(No Transcript)
36
(No Transcript)
37
(No Transcript)
38
Find the Secret MessageHint Look at the White.
39
There Is Not a Triangle Here.
40
This Is a Dancing Elephant. How Many Feet and
Legs Does It Have?
41
A Man With Ivy Leaves Around Him, but Do You See
a Couple Kissing?
42
And finally - What Does This Say?
43
(No Transcript)
44
(No Transcript)