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40 Cards in this Set

  • Front
  • Back
• Receptors must respond to light energy
• Light energy – small part of electromagnetic energy
• Visible spectrum is 400 nm to 700 nm range
• 2 types of receptors in the retina.
o Rods – 1 type – respond to a wide portion in the visible spectrum. Used when light energy is low (dim light).
o Cones – 3 types – each type of cone has a different but overlapping part of the visible spectrum. (bright light receptors).
vision
_________ must respond to light energy
Receptors
small part of electromagnetic energy
Light energy
Visible spectrum is ____ nm to ____ nm range
400 - 700
What are the two types of receptors in the retina?
rods and cones
– 1 type – respond to a wide portion in the visible spectrum. Used when light energy is low (dim light).
rods
– 3 types – each type of ____ has a different but overlapping part of the visible spectrum. (bright light receptors).
cones
• As light passes through objects of different densities it is bent (refracted)
• Cornea refracts light the most (can’t use to control light)
• Lens is the most significant structure that refracts light and thus focuses light energy, because it can CHANGE the amount of light refraction it causes.
• Lens changes refraction by changing shape.
• The process of changing lens shape to focus light rays on the retina is called ACCOMMODATION.
Optics of vision
As light passes through objects of different densities it is _____ or _________.
bent
refracted
_______ refracts light the most (can’t use to control light)
Cornea
_____ is the most significant structure that refracts light and thus focuses light energy, because it can CHANGE the amount of light refraction it causes.
Lens
____ changes refraction by changing shape.
Lens
The process of changing lens shape to focus light rays on the retina is called _____________.
ACCOMMODATION
1. Light rays from close objects must be bent more to focus them on the retina.
2. Because light energy strikes the eye at greater angles from close objects.
a. Focusing the image we are most concerned w/on a small area of the retina called the fovea. Why?
i. Fovea has dense pattern of CONES
ii. Provides for visual acuity – ability to see detail
accommodation
Light rays from close objects must be bent more to focus them on the ______.
retina
______ _______ strikes the eye at greater angles from close objects.
Light energy
Focusing the image we are most concerned w/on a small area of the retina called the ______.
fovea
Why is the image focused on the fovea in the retina?
Fovea has a dense pattern of CONES
Provides for visual acuity – ability to see detail
• Due to how the photoreceptors are conn. to the visual pathways.
• 1 cone synapses on 1 bipolar cell & each bipolar cell synapses on 1 ganglion cell.
• Each cone has its own direct connection to the CNS. Provides greater detail about visual images.
• Several RODS synapse on a single bipolar cell.
• Several bipolar cells synapse on 1 ganglion cell.
• Thus sensory info sent to the brain is not as detailed when using RODS as the photoreceptors.
visual acuity
Due to how the photoreceptors are conn. to the visual pathways.
visual acuity
When does 1 cone synapses on 1 bipolar cell & each bipolar cell synapses on 1 ganglion cell?
happens during visual acuity
Each ____ has its own direct connection to the CNS. Provides greater detail about visual images.
cone
Several ____ synapse on a single bipolar cell.
rods
Several bipolar cells synapse on 1 _________ cell.
ganglion
Thus sensory info sent to the brain is not as detailed when using _____ as the photoreceptors.
rods
What is controlled by the 2 sets of smooth muscles w/in the iris of the eye?
the regulation of light entering the eye
controlled by PNS. Decrease pupil diameter.
circular muscles –
controlled by SNS : increase pupil diameter
Radial muscles –
Rods & cones are found in the deepest parts of the _______. Light must pass through all retinal layers before reaching the _____________.
retina
photoreceptor
1. contain pigments – rhodopsin
2. Rhodopsin composed of a protein portion (an opsin) and a chromophore (retinal).
3. The combination absorbs light in a particular pattern & the effected retinal changes its shape.
4. Initiates a series of chemical reactions
5. Causes the rods to HYPERPOLARIZE (inhibiting)
6. Causes a DECREASE in the amount of Glutamate (inhibitory neurotransmitter) released at the synapse w/ the bipolar cells.
7. causes the bipolar cells to DEPOLARIZE.
8. Bipolar cells release a neurotransmitter (excitatory) that DEPOLARIZES ganglion cells, leading to action potential generation.
9. Action potential then travels through visual pathways to the brain.
rod function
___________ composed of a protein portion (an opsin) and a chromophore (retinal).
rhodopsin
Which photoreceptor contains pigments called rhodopsin
rods
What causes the rods to HYPERPOLARIZE (inhibiting)?
a series of chemical reactions
• 3 types of _____ , each w/ a different opsin & retinal (photopigment)
o Each opsin bonds differently to retinal
o Thus each type of photopigment responds maximally to different wavelengths of light.
o Therefore, each _____ type responds differently to a given wavelength of light.
o The relative amount of response by a given _____ type to a given stimulus is the major input sent to the brain where color perception is determined.
cones
______ _______ then travels through visual pathways to the brain.
action potential
3 types of cones, each w/ a different ______& _______(photopigment)
opsin
retinal
Each opsin bonds differently to ________.
retinal
Each type of ___________ responds maximally to different wavelengths of light.
photopigment
Each cone type responds differently to a given ___________of _____.
wavelength
light
The relative amount of response by a given cone type to a given stimulus is the major input sent to the brain where ______ __________ is determined.
color perception