Flashcards in Chapter 2: Beginnings Of Perception Deck (28):
What is electromagnetic spectrum?
A continuum of electromagnetic energy that is produced by electrical charges and is radiated as waves
What is a wavelength?
Energy described by its wavelength. The distance between the peaks of the electromagnetic waves.
Gamma ray and radio wave lengths?
G: 10^-12 meters
R: 10^4 (10000 meters)
Pupil: hole in your eye that lets in light
Cornea: outer layer that covers pupil iris and interior chamber (80% of focusing)
Lens: behind iris, transparent structure that adjusts shape for object distance, other 20% of focus
Eye parts 2?
Retina: light-sensitie tissue lining back of eye, has receptors for vision
Sclera: white part of eye
Visible light spectrum?
Ranges from 400-700 nanometers.
What is the near point?
The distance in which your lens can no longer adjust to being object into focus
What is presbyopia?
When the distance of the near point increases with age.
Near point focus ages
20 yrs- 10cm
30 yes- 14cm
What is myopia(nearsided) and what it does?
Inability to see objects far away. Bends light too much. Axial myopia is eyeball too long
What is the far point?
Distance at which light becomes focused on retina and can be seen clearly
What is hyperopia?
Farsightedness. Trouble seeing close up. Eyeball is too short.
Disc: top part of rod
Outer segment: Sheath over head
Inner segment: part between tail and head
Synaptic pedicle: fish tail
Molecule name and anatomy?
An opsin, part is retinal
What is Hecht’s psychophysical experiment?
-prior physical evidence showed that it takes one photon to isomerize a pigment molecule
-purpose of experiment is to determine how many pigment molecules beed to be isomerizes for a person to see
-method of constant stimuli used to determine absolute threshold
Results show: a person can see light if seven rod receptors are activated simultaneously
What is isomerization?
When a retinal changes its shape
An enzyme cascade. Means a single reaction leads to increasing numbers of chemical reactions.
Consists only of cones
Peripheral retina has.... and more....
Both cones and rods, more rods than cones
Numbers if rods and cones
120 mill rods and 5 mill cones
What is macular degeneration?
-fovea and small surrounding area destroyed
-creates blind spots on retina
-common in elderly
What is retinitis pigmentosa?
-rods are destroyed first
-foveal cones attacked maybe
-can cause blindness
Rod pigment absorbs best at...
Cone pigment absorbs best at...
419nm, 531nm, 558nm
Absorption of all cones equals peak of...
560nm in spectral sensitivity curve
Rods and cones send signals vertically through...
Signals are sent horizontally through...
-between receptors by horizontal cells
-between bipolar and between ganglion cells by amacrine cells