Chapter Six Flashcards
Transduction
physical stimulation –> brain activity
In humans, which sensation has more brain devoted to it?
Vision
In rodents, which sensation has more brain devoted to it?
olfaction
what exactly is light?
a wave of which we see a narrow range
Sclera
the white membrane on outside of eye; not transparent-no light can pass through
Cornea
transparant film on the front of the eye; one of the fastest repairing tissues
Iris
muscle that regulates amount of light that comes into the eye; changes size of pupil
Pupil
hole in the front of the eye
Lens
directly behind the pupil; focuses light waves as they come into the eye
Accommodation
the lens literally changes shape
Vitreous Humor
gel-like; allowed eye to keep spherical shape
Retina
nervous tissue; where light (which comes in right to left) gets focused
Retina is made up of three cell types
photoreceptors, bipolar cells, ganglion cells
Photoreceptors
very back of the retina; rods & cones
Bipolar cells
middle
Ganglion cells
front of the retina; axons make up the optic nerve
Rods
(120 mil) outside edge of retina; seeing with low light levels
Cones
(6 mil) middle of retina; color vision, visual acuity-seeing in detail
Pigment in the photoreceptors
Opsin (protein) and retinal (lipid)
What are the colors of cones?
red, blue, and green
What does contact with light do to the photopigment?
splits the photopigment
What does the split in the photopigment cause?
change in release of glutamate (excitatory) , which causes chain reaction
What is the end result with the photoreceptors?
ganglion cells are stimulated and these cells make up the optic nerve