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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

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