Flashcards in E2 Perception of Stimuli Deck (8)
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1
List the four kinds of human sensory receptors and their functions
Mechanoreceptors - changes in pressure and texture
Chemoreceptors - changes in taste and smell
Photoreceptors - changes in light
Thermoreceptors - changes in temperature
2
State two similarities between cone and rod cells
• Both types of cell are photoreceptors
• Both types of cell are found in the retina
3
Distinguish between cone and rod cells with respect to their optimal light conditions
Rod cells are better in dim light, while cone cells are better in bright light
4
Distinguish between cone and rod cells with respect to the type of vision they provide
Rod cells provide black and white, while cone cells provide colour
5
Distinguish between cone and rod cells with respect to their relative abundance
There are much more rod cells than cone cells
6
Distinguish between cone and rod cells with respect to their location
Rod cells are found throughout the retina, while cone cells are concentrated around the fovea
7
Explain the processing of visual stimuli
• Lens focuses light onto rod and cone cells in the retina
• Visual stimuli are processed by the retina and visual cortex in the brain
• Bipolar cells in the retina combine impulses from groups of rod or cone cells and pass them on to ganglion cells
• Receptive field is region of retina which communicates with one ganglion
• Low ratio of cone/ganglion cells in the fovea gives high acuity (small visual fields)
• There are two types of ganglion cells
• One type of ganglia are stimulated by light hitting the centre of the receptive field and inhibited by light hitting the edge (and vice-versa)
• Edge enhancement occurs when light/dark edges fall in the receptive field
• Both the left and right visual cortex process images from both eyes
• The optic nerves carries impulses from the retina to the visual cortex
• Stimulus from the right visual field of both eyes is processed in the right visual cortex (and vice-versa)
• This crossing over of nerves is called contralateral processing, and is facilitated by the optic chiasm
8