E2 perception of stimuli
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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

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E2 – Perception of stimuli

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E2 perception of stimuli

E2 – Perception of stimuli

Human eye

Human ear


Human sensory receptors

Human sensory receptors

  • receptors 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

Human sensory receptors & stimuli that can detect

Type of receptor

Stimulus detected

Example of receptors

mechanoreceptors

pressure, sound

hair cells in the ear

chemoreceptors

chemical substances

taste buds on the tongue & olfactory cells along the nose

thermoreceptors

temperature

nerve endings in the skin & hypothalamus of the brain

photoreceptors

light

rods and cone in the retinas of the eye

hydroreceptors

humidity

?

nocireceptors

pain

sensory nerve ending in the skin


E2 perception of stimuli

Human eye

Eye lashes

Sclera

Pupil

Iris

Eye lid


Label the diagram of the human eye below

Label the diagram of the human eye below

sclera

pupil

choroids

retina

ciliary body / muscles

iris

lens

cornea

fovea

blind spot

optic nerve


E2 perception of stimuli

Structure

Function(s)

tough outer layer of the eye which overs and protect eyeball.

Sclera

Choroid

prevents internal reflection of light and nourish retina.

Retina

contains rods and cones which convert light into nerve impulses.

Ciliary Body

a ring of muscle controlling the shape and curvature of the lens.

Iris

controls the pupil size thus controls entry of light.

Pupil

a hole in the iris that lets light into the back of the eye.

Lens

accommodation & focusing of light onto the retina.

Cornea

bends incoming light focusing it on the retina.

Fovea

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

Blind Spot

Optic Nerve

carries the impulses from the rods and cones to the visual center of the brain.


Annotate the diagram of the retina below

Annotate the diagram of the retina below

Axon of the ganglion cell

direction of light movement

Ganglion cell

Bipolar cell

Synapse

Rod

Cone

Pigment

Sclera


Compare rod and cone cells

Compare rod and cone cells

Rod Cells

Cone Cells

rod cells more effective in low light intensity

cone cells more effective in high light intensity

cone cells are sensitive to a specific colours (wavelength)

rod cells detect a broad range of colours (wavelength)

a single cone cell passes impulses to a single nerve fibre

groups of rod cells pass 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


Compare rod and cone cells1

Compare rod and cone cells

Rod Cells

Cone Cells

rod and cone cells are both are photosensitive

  • 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)


Contralateral processing of visual stimuli

Contralateral processing of visual stimuli

  • rod & cone cells in the retina convert light into nerve impulses

  • impulses pass to bipolar cells

  • bipolar 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 enhancement

Edge enhancement

  • edge 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 below

Label the diagram of the ear below

Semi circular canals

Middle ear bones

Oval Window

Auditory Nerve

Round window

Cochlea

Eustachian tube

Eardrum

Auditory canal

Pinna


How sound is perceived by the ear

How sound is perceived by the ear

  • sound waves reaching eardrum cause it to vibrate

  • vibrations 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 cochlea

  • As 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


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