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Flashcards in E2 Perception of Stimuli Deck (8)
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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


State two similarities between cone and rod cells

• Both types of cell are photoreceptors
• Both types of cell are found in the retina


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


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


Distinguish between cone and rod cells with respect to their relative abundance

There are much more rod cells than cone cells


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


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


Explain how sound is perceived by the ear

• Sound waves are collected by the pinna
• Ear drum vibrated by air pressure changes (due to sound waves)
• Middle ear bones stimulated by ear drum, enhancing sound by 20x
• Oval window transmits vibrations from middle ear bones to cochlea
• Tiny hairs in cochlea act as receptors for individual wavelengths of sound
• Action potential generated in the cochlea
• Auditory nerve transmits action potential to brain
• Round windows of cochlea dissipate sound