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E2 – Perception of stimuli. Human eye. Human ear. Human sensory receptors. receptors detects the changes in both internal and external environment - PowerPoint PPT Presentation
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E2 – Perception of stimuli
Human eye
Human ear
Human sensory receptorsreceptors detects the
changes in both internal and external environment
they transform the stimuli energy into a nerve impulse that can be sent to the central nervous system (CNS) which in turn coordinates an appropriate response.
receptors are located in the sense organs such as the eye, ear, skin, tongue etc.
Human sensory receptors & stimuli that can detect
mechanoreceptors
chemoreceptors
thermoreceptors
photoreceptors
nocireceptors
hydroreceptors
pressure, sound
chemical substances
temperature
light
pain
humidity
hair cells in the ear
taste buds on the tongue & olfactory cells along the nosenerve endings in the skin & hypothalamus of the brain
rods and cone in the retinas of the eye
?
sensory nerve ending in the skin
Example of receptorsStimulus detected
Type of receptor
Eye lashes
Sclera
Pupil
Iris
Eye lid
Human eye
Label the diagram of the human eye belowsclera
choroids
retina
ciliary body / muscles
iris
lens
cornea
fovea
blind spot
optic nerve
pupil
Structure
Sclera
Choroid
RetinaCiliary Body
Iris
Pupil
Lens
Cornea
Fovea
Blind SpotOptic Nerve
Function(s)
tough outer layer of the eye which overs and protect eyeball. prevents internal reflection of light and nourish retina. contains rods and cones which convert light into nerve impulses. a ring of muscle controlling the shape and curvature of the lens.
controls the pupil size thus controls entry of light.
a hole in the iris that lets light into the back of the eye.
accommodation & focusing of light onto the retina.
bends incoming light focusing it on the retina.
a tiny area of densely packed cones for detailed and coloured vision. exit point of the optic nerve cutting through the retina so no rods or cones carries the impulses from the rods and cones to the visual center of the brain.
Annotate the diagram of the retina belowdi
rect
ion
of li
ght
mov
emen
t
Pigment
Cone
Rod
Bipolar cell
Ganglion cell
Synapse
Sclera
Axon of the ganglion cell
Compare rod and cone cells
rod cells more effective in low light intensity
cone cells are sensitive to a specific colours (wavelength)
cone cells more effective in high light intensity
rod cells detect a broad range of colours (wavelength)groups of rod cells pass impulses to a single nerve fibre
a single cone cell passes impulses to a single nerve fibre rod cells more sensitive to
movement cone cells give higher visual acuity (sharpness )
rod cells respond more slowly to light
cone cells respond more rapidly to light
rod cells spread through retina cone cells concentrated in centre of retina (at fovea )
rod cells contains one type of pigment (rhodopsin)
cone cells contains three types of pigment (iodopsin)
rod and cone cells are both are photosensitive
Rod Cells Cone Cells
Compare rod and cone cellsRod Cells Cone Cells
cone cells more effective in high light intensity
cone cells are sensitive to a specific colours (wavelength)
a single cone cell passes impulses to a single nerve fibre
cone cells give higher visual acuity (sharpness )
cone cells respond more rapidly to light
cone cells concentrated in centre of retina (at fovea )
cone cells contains three types of pigment (iodopsin)
rod cells more effective in low light intensity
rod cells detect a broad range of colours (wavelength)
groups of rod cells pass impulses to a single nerve fibre
rod cells more sensitive to movement
rod cells respond more slowly to light
rod cells spread through retina
rod cells contains one type of pigment (rhodopsin)
rod and cone cells are both are photosensitive
Contralateral processing of visual stimulirod & cone cells in the retina
convert light into nerve impulses
impulses pass to bipolar cellsbipolar cells pass impulses to
sensory neurons of the optic nerve
at the optic chiasma, impulses cross over to the opposite optic nerve
impulses continue to the thalamus where optical information is processed
images form in the visual cortex of the brain
Edge enhancementedge enhancement is a ‘pre-
central nervous system ‘processing of information on the retina
it enhances contrast at the edges (boundaries of different objects) and provides more detail to the visual system of the environment
in certain regions of the retina, single ganglion cell receives information form a number of rods and cones, such a region is called receptive field
the fewer the rods and cones that supply a single ganglion the smaller the receptive field & the higher visual acuity i.e. the detailed information one sees
Label the diagram of the ear belowMiddle ear bones Semi circular canals
Oval Window Auditory Nerve Round window CochleaEustachian tube EardrumAuditory canalPinna
How sound is perceived by the ear
sound waves reaching eardrum cause it to vibratevibrations are passed to bones of middle ear which amplify them the bones pushes the oval window which cause a pressure wave in the fluid-
filled cochleaAs the oval window moves in, the round window moves out, this allows the
fluid in the cochlea to move freely backward & forward the vibrations caused by fluid movement pushes the membrane on which the
hair cells (mechanoreceptors) sits, triggering nerve impulses in the auditory nerves
the nerve impulse is carried to the auditory cortex in brain through auditory nerve for interpretation
