Flashcards in 17. Retinal Function and Visual Perception Deck (45)
What range of electromagnetic wave length is visible to the eye?
What does length of an electromagnetic wave correspond to?
What does amplitude of an electromagnetic wave correspond to?
What effect does a closer light source have on the focal distance?
Longer focal distance
What is accommodation?
Lens alters focal length
What are the functions of the pupil?
Control light entering eye
Depth of focus
How does the pupil control depth of focus?
Constriction cuts out peripheral light
What is the effect of sympathetics on the pupil?
Contract radial muscle of iris
What is the effect of parasympathetics on the pupil?
Contract circular muscle of iris
What is used to test for visual acuity?
What is visual acuity?
Ability to distinguish between 2 nearby points
What does each part of 20/20 stand for?
First 20 is distance in feet from Snellen chart
Second is size of the smallest letter read
What are the 3 cell types in the retina?
What do rods detect?
Why is visual acuity low in rods?
Many rods converge to the same ganglion
What do cones detect?
What is the equation for photon energy?
hv (planck constant x frequency)
hc/ λ (planck constant x speed of light/ wavelength)
Which cells are non-image forming photoreceptors?
Retinal Ganglion Cells
What do Retinal Ganglion cells control?
What light-sensitive pigement is used by retinal ganglion cells?
What is the name for loss of photoreceptor cells?
What is found in the outer segment of cones?
Discs: specialised receptor region
What is found in the inner segment of cones?
Mitochondria and other organelles
What is phototransduction?
Converting light to an electrical signal
What pigment is used in rods?
What is rhodopsin composed of?
Retinal and opsin
What neurotransmitter is released by rods?
What is meant by the dark current?
Na+ enters causing depolarisation
K+ leaves causing repolarisation
What happens once light hits rhodopsin?
11-cis retinal converted to 11-trans retinal