SAFMEDs Chapter 6: Sensations Flashcards
Sensation
-The process by which our brain and nervous system receive input from the environment through our five senses
Transduction
- one form of energy transforms into another
- electromagnetic light waves are received by our sense of vision and transformed into electrochemical energy our brains can understand
Wavelength
- the distance from one wave peak to the next
- the brain is able to determine the wavelength by how active each of the color cones is
Intensity
- the amount of a wave’s energy
- measured by amplitude or height
Photoreceptor
- transduce light energy into electrochemical energy
- light receptor cells
- turns light into nerve impulses
Hue
- comes in red, green or blue
- the color we experience
Visible spectrum
-the band of wavelengths the human eye can see
Cornea
- the outer layer of the eye
- transparent, convex, covers the front of the eye
- bends light toward the center of the eyeball
Iris
- the colored part of the eye
- adjusts the dilating and constricting in response to the brightness in the environment to let in more or less light
- muscle
Pupil
- the black part at the center of the eye
- the product of the opening the iris creates
Lens
- transparent structure behind the pupil
- cureved and flexible
- changes curvature to help focus images
- flips the image and focuses the inverted image
Aqueous humor
- chamber behind the pupil and iris
- filled with watery fluid
Vitreous humor
-jelly like fluid that light waves pass through before hitting the retina
Retina
-light sensitive layer at the back of the eye
Visual accommodation
-the process bby which the lens flips an image and focuses the inverted imahe before passing through to the retina
Rods
- photoreceptors that detect black/white/grey
- work in very dim light
- “night vision”
Cones
- photorecptors that function in bright light
- located in and around the fovea
- three types: red, green, blue
- allow us to perceive color
- the brain is able to determine the wavelength by how active each of the color cones is
Fovea
- the central point of the retina
- part of the macula
- cones are located in and around
Optic Nerves
-the nerves that send signals from the eyes to the brain
Optic chiasm
-where the fibers from each optic nerve crosses into the opposite side of the brain
Peripheral vision
- the eye’s ability to see things on the side of our field of vision when looking straight ahead
- not as good as our ability to see things straight on
Blind spot
- The disc where the ganglion cells meet at the back of the eye
- Since it is a hole in the retina there are no photoreceptors present
- you cannot see there
Saccade
- reflexive rapid eye movement from side to side
- keeps different neurons firing
- fills in the missing information created by the blind spot
- occurs during reading, talking in a scene and certain stages of sleep
Dark Adaptation
- the ability to adapt to quickly darkening conditions
- pupil opens quicly to allow for more light waves to enter the eye
- Increased retinal sensitivity in the rods
- going from a bright hallway to a dark movie theater
Rhodopsin
- a light-sensitive pigment in the rods that helps the rods deal with low-light conditions
- overexposure to sunlight decreases this chemical
Feature Detectors
- react to the strength of visual stimuli
- responds to shapes, angles, edges, lines and movement in our field of vision
- feature detectors in other locations in the brain have specialized functions
- the brain takes the information received from feature detectos and makes a series of interpretations that allow us to see what we see
Parallel Processing
- the brain can multitask
- color, motion, shape and depth are processed simultaneously by feature detectors
Trichromatic Theory (Young-Helmholtz
- earliest theory about why we can only see color on the visible spectrum
- the three cone types in the retina work together to potray a range of colors, producing only red, green or blue
- we see a specific color by comparing responses from the three types of cones
- color depends on the strength of cone types that are firing
- when all three cones are equally active we see white or gray
Opponent-Process Theory
- focuses on brain processes rather than the eye
- three opponent channels (red-or-green, blue-or-yellow, black-or-white)
- light waves will excite one color in a pair that will inhibit the excitation in its opposing color
- black-white are achromatic and detect luminace (light-dark changes)
Afterimage
- a visual sensation that remains after the stimulus is removed
- staring at one color fatigues the sensors for that color
Color blindness
- the inability to perceive color differences
- caused by a lack of shoty, medium or long wavelength cones in the fovea
- gentic condition caused by the recessive trait on a chromosome
- diagnosed using the Ishihara test (dot test)
- color deficiency occurs in 8% of men and 1% of women
- total color blindness is rare
Audition
-the biological proces by which our ears process sound waves
Amplitude
-affects the psychological quality of loudness (sound pressure or intensity)
Pitch
-affected by the wavelength of sound waves
Frequency
- the number of wavelength cycles in a unit of time
- measured in Hz
Pinna
-the outer ear
Auditory canal
- ear canal
- catches sound waves
Tympanic membrane
- eardrum
- is vibrated
