Ch.5 Sensation Flashcards
Adaptation
Refers to the decreasing response of the sense organs, the more they are exposed to a continuous level of stimulation
Transduction
Refers to the process in which a sense organ changes, or transforms, physical energy into electrical signals that become neural impulses, which may be sent to the brain for processing
Sensations
Relatively meaningless less bits of information that result when the brain processes electric signals that come from the sense organs
Perceptions
Meaningful sensory experiences that result after the brain combines hundreds of sensations
When you see an object, the eye
Reverses the image so it’s upside down in the eye but the brain turns objects we see right side up so we see the world as it is
Cornea
The rounded transparent covering over the front of your eye
The curved surface of the cornea focuses and bends light waves into a narrower beam
Pupil
- Light passes through pupil after passing through the cornea
- A round opening at the front of hour eye that allows light waves to pass into the eye’a interior
- Grows larger or smaller because of iris
Iris
- A circular muscle that surrounds the pupil and controls the amount of light entering the eye
- iris contains pigment which gives eyes the color
What does an iris do in dim light? In bright light?
Dim light-iris relaxes, allowing more light to enter and the pupil dilates
Bright light-iris constricts, allowing less light to enter, pupil constricts
Lens
- A transparent, oval structure whose curved surface bends and focuses light waves into an even narrower beam
- the lens is adjusted to muscles that adjust the curve of the lens which adjusts the focusing
Retina
- located at the very back of the eyeball
- a thin film that contains cells that are extremely light sensitive (photoreceptors) and begin the process of transduction by absorbing light waves
Nearsightedness occurs when
The eyeball is too long so that objects are focused at a point in front of the retina
Farsightedness (hyperopia) occurs when
The eyeball is too short and objects are focused slightly behind the retina
How many layers does the retina have
3 layers of cells
Fovea
Location of many cones in the eye and is in the center of the retina
Rods have.
Rhodopsin
Cones have…
Opsins
Rods allow us to see
In dim light but only in black and white with shades of gray
Cones allow us to see
Color and fine details
Transduction in the eye occurs when:
- Rods and cones breakdown after absorbing light waves
- Breakdown of the cells generates a tiny electrical force which will
- trigger nerve impulses in neighboring ganglion cells
Blind spot in the eye
The point where the optic nerve exits the eye and goes to the brain
Layers of the retina
Back layer:rods and cones (where transduction occurs)
Middle layer: ganglion cells which is where impulses begin
Front layer: contains nerve fibers which carry impulses to brain
Impulses go to which brain parts
Optic nerve ➡️thalamus➡️primary visual cortex➡️visual association areas
Thalamus role in vision
Does some initial processing then relays the impulses to the occipital lobe
Function of primary visual cortex in vision
Turns impulses into basic lines and shadows
Visual agnosia
Having difficulty in assembling simple visual sensations into more complex meaningful images
Visual association area
Turns meaningless info from the primary visual cortex into meaningful images
Red wavelength
The longest of all the colors we can see
Trichromatic theory
Says that there are three different kinds of cones in the retina and each cone contains one of three opsins
Three opsins show colors of red, blue, or green
Creator of the trichromatic theory
Thomas young