Irritability
- Ability to detect stimuli + give appropriate responses
Importance: survival
- Obtain food
- Butterflies detect nectar smell > fly to flowers and feed on nectar
- Plant shoots detect light source > grow towards it to get light for
photosynthesis
- Find mates
- Peahens see feather display of peacocks > approach peacocks for mating
- Escape from danger
- Rabbits hear predators’ sound > run away quickly
stimulus → response
Receptors: Receptors generate nerve Effectors (motors, glands)
Sensory cells (of sense impulses give responses
organ) > sent along nerves to
coordinator (nervous
Each type of receptor system: brain 腦 +
detects specific kind of endocrine system)
stimulus > brain interpret nerve
- Photoreceptor on impulses, give sensation
eye 眼 > light > brain sends nerve
- Mechanoreceptor in impulses to effectors
ear 耳 > sound
- Chemoreceptor on
tongue 舌 >
chemicals in food
- Chemoreceptor in
nose 鼻 > chemicals
in air
- Mechanoreceptor on
skin 皮膚 > pressure,
vibration, stretching
- Thermoreceptor on
skin 皮膚 > temp
change
Human eye
- Sense organ detecting light
, Structure
Structures ard the eye Structures of the eye
Eyebrow: prevent sweat from getting into Sclera (outermost layer, opaque, tough):
eye protect inner delicate structures, maintain
Eyelash: trap dust and flying objects from shape of eyeball, provide surface for
entering the eye attachment of eye muscles
Eyelid @orbit (socket in skull): closed > Cornea (transparent, curved, X capillaries):
protect eye from dirt and strong light; blink > allow light pass thru + enter eye,
spread tears over eye surface refract+focus light onto retina
Tear gland: produces tears (Na, Cl, Iris (muscle continuous w sclera, w
lysozyme > kill bacteria), keep eye moist pigment): control pupil size, regulate amt of
and clean light entering eye
Tear duct: drains tears into nasal cavity Pupil: allow light to enter eye
Eye muscles (3x pairs): enable eyeball to Lens (transparent, elastic, biconvex; living
rotate in diff directions cells w/o nuclei, X capillaries): allow light
Conjunctiva (transparent membrane pass thru, refract+focus light onto retina
covering part of front surface of eyeball, Ciliary body + suspensory ligament :
inner surface of eyelids): keep front part of produce aqueous humour, ciliary muscles
eye moist and lubricated control tension of suspensory ligaments >
change thickness of lens to focus light from
object @diff distances onto retina
Retina (innermost layer, 1 layer of cells:
nerve fibres + photoreceptors)
Choroid (middle layer, black pigment, rich
in capillaries): absorbs light + reduce
internal reflection of light to form sharp img,
supply nutrients+O2 to retina/sclera,
remove wastes
Optic nerve (nerve fibres @retina
grouped): transmit nerve impulses
generated from photoreceptors @retina to
visual centre in cerebral cortex in cerebrum
of brain
Aqueous humour @anterior chamber
(watery, produced by ciliary body): supplies
nutrients+O2 to cornea/lens by diffusion
from capillaries @choroid, maintain convex
shape of cornea + spherical shape of
eyeball, refract light onto retina
Vitreous humour @posterior chamber
(clear, jelly-like): maintain convex shape of
cornea + spherical shape of eyeball, refract
light onto retina
Blind spot (where optic nerve leaves
eyeball): X photoreceptors > X nerve
impulses sent to brain when img fall here
Yellow spot (retina centre): conc w cone
cells, X rod cells
- Ability to detect stimuli + give appropriate responses
Importance: survival
- Obtain food
- Butterflies detect nectar smell > fly to flowers and feed on nectar
- Plant shoots detect light source > grow towards it to get light for
photosynthesis
- Find mates
- Peahens see feather display of peacocks > approach peacocks for mating
- Escape from danger
- Rabbits hear predators’ sound > run away quickly
stimulus → response
Receptors: Receptors generate nerve Effectors (motors, glands)
Sensory cells (of sense impulses give responses
organ) > sent along nerves to
coordinator (nervous
Each type of receptor system: brain 腦 +
detects specific kind of endocrine system)
stimulus > brain interpret nerve
- Photoreceptor on impulses, give sensation
eye 眼 > light > brain sends nerve
- Mechanoreceptor in impulses to effectors
ear 耳 > sound
- Chemoreceptor on
tongue 舌 >
chemicals in food
- Chemoreceptor in
nose 鼻 > chemicals
in air
- Mechanoreceptor on
skin 皮膚 > pressure,
vibration, stretching
- Thermoreceptor on
skin 皮膚 > temp
change
Human eye
- Sense organ detecting light
, Structure
Structures ard the eye Structures of the eye
Eyebrow: prevent sweat from getting into Sclera (outermost layer, opaque, tough):
eye protect inner delicate structures, maintain
Eyelash: trap dust and flying objects from shape of eyeball, provide surface for
entering the eye attachment of eye muscles
Eyelid @orbit (socket in skull): closed > Cornea (transparent, curved, X capillaries):
protect eye from dirt and strong light; blink > allow light pass thru + enter eye,
spread tears over eye surface refract+focus light onto retina
Tear gland: produces tears (Na, Cl, Iris (muscle continuous w sclera, w
lysozyme > kill bacteria), keep eye moist pigment): control pupil size, regulate amt of
and clean light entering eye
Tear duct: drains tears into nasal cavity Pupil: allow light to enter eye
Eye muscles (3x pairs): enable eyeball to Lens (transparent, elastic, biconvex; living
rotate in diff directions cells w/o nuclei, X capillaries): allow light
Conjunctiva (transparent membrane pass thru, refract+focus light onto retina
covering part of front surface of eyeball, Ciliary body + suspensory ligament :
inner surface of eyelids): keep front part of produce aqueous humour, ciliary muscles
eye moist and lubricated control tension of suspensory ligaments >
change thickness of lens to focus light from
object @diff distances onto retina
Retina (innermost layer, 1 layer of cells:
nerve fibres + photoreceptors)
Choroid (middle layer, black pigment, rich
in capillaries): absorbs light + reduce
internal reflection of light to form sharp img,
supply nutrients+O2 to retina/sclera,
remove wastes
Optic nerve (nerve fibres @retina
grouped): transmit nerve impulses
generated from photoreceptors @retina to
visual centre in cerebral cortex in cerebrum
of brain
Aqueous humour @anterior chamber
(watery, produced by ciliary body): supplies
nutrients+O2 to cornea/lens by diffusion
from capillaries @choroid, maintain convex
shape of cornea + spherical shape of
eyeball, refract light onto retina
Vitreous humour @posterior chamber
(clear, jelly-like): maintain convex shape of
cornea + spherical shape of eyeball, refract
light onto retina
Blind spot (where optic nerve leaves
eyeball): X photoreceptors > X nerve
impulses sent to brain when img fall here
Yellow spot (retina centre): conc w cone
cells, X rod cells
