Chapter 1 the World Through Our Senses
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Transcript of Chapter 1 the World Through Our Senses
CHAPTER 1 ~ THE WORLD THROUGH OUR SENSES
1.1 Sensory Organs and the Nervous Pathway
Sensory organs Stimulus detected Main function
Skin 皮肤 Touch, pain, heat, cold, pressure Organ for touch
Nose 鼻子 Chemicals Organ for smell
Tongue 舌头 Chemicals Organ for taste
Ear 耳朵 Sound Organ for hearing
Eye 眼睛 Light Organ for sight
1.2 The Sensory Organs of Touch, Smell and Taste
The Skin
Pathway for touch
The factors that sensitive to the skin are thickness of epidermis and numbers of receptors.
口诀:Epidermis 有两个 receptors,就是 touch receptor 和 pain receptor.
Dermis 有两个 receptors,就是 heat receptor 和 cold receptor.
内层有一个 pressure receptor.
The Nose
Stimuli → receptors → nervous impulses↓
Sensation is ← nervous ← brain (impulses identified impulses interpreted)
Chemical → dissolve → stimulate sensorysubstances in muscle cells
Pathway for smell
The Tongue
Pathway for taste
1.3 The Sensory Organ of Hearing
The ear is the organ of hearing.
Sound
Food dissolves → dissolved food → nervous In saliva stimulates impulses
taste buds
Taste is brain Identified (interprets
impulses)
soundsound vibrations
耳廓 耳道 耳膜 耳骨
听觉神经 耳蜗 耳窗
The pathway for hearing
口诀: 小明 Ponteng Class 就回去 CC 店打 Dota, O2 jam, Counter.
如果妈妈没有抓到就 Amituofo.
1.4 The Sensory Organ of Sight
The eye
Parts of the Eye and Their Functions
Pinna Auditory cannal Eardrum Ear
ossicles
Oval window
CochleaAuditory nerve
Brain for identification
of sound
vibrations
vibrations
impulse impulse
Part Functions
Sclerotic coat (sclera) Protects the eye and maintains its shape
Choroid Absorbs light to prevent reflection in the eyeball
Retina 视网膜 Send impulses to the brain when it is stimulated by an image formed on it
Yellow spot 视点 A spot on the retina which is most sensitive to light
Optic nerve 视觉神经 Carries impulses from the retina to the brain for interpretation
Blind spot 盲点 Not sensitive to light or image which falls on it
Vitreous humour Transmits light and prevents the eyeball from collapsing
Lens 晶体 Focuses light and forms an image on the retina
Aqueous humour Nourishes and cools the eye
Pupil 瞳孔 Permits the entry of light into the eye
Iris 虹膜 Controls the size of the pupil for the entry of light
Cornea 眼角膜 Helps to focus an image on the retina
Suspensory ligament Holds the eye lens in positionCiliary muscle Controls the thickness of the lens for focusing the image.
The pathway for sight
口诀:LV 牌 CAP 被 ROB,所以眼睛就留下了眼泪.
1.5 Light and Sight
1. This causes the formation of shadows and eclipses of the sun and the moon.
Cornea Aqueous humour Pupil Lens
Vitreous humourRetinaOptic
nerveBrain
light light light
light
impulse lightimpulse
Light
2. The image in a plane mirror is due to the mirror reflecting light from the object to the observe.
Refraction of Light折射
1. The light is refracted towards the normal when it passes from a less dense medium to a denser medium, e.g from air to glass.
2. The light is refracted away from the normal when it passes from a denser medium to a less dense medium, e.g from glass to air.
Short-sightedness and Long-sightedness
Short-sightedness近视 Long-sightedness远视
A distant object cannot be seen clearly because the image is focused in front the retina.
This is because the eye lens is too thick or the eyeball is too long.
It is corrected by using a concave lens to diverge the rays of light on the retina.
A near object cannot be seen clearly because the image is focused behind the retina.
This is because the eye lens is too thin or the eyeball is too short.
it is corrected by using a convex lens to converge the rays of light on the retina.
Stereoscopic Vision and Monocular Vision
Stereoscopic vision 双眼 Differences Monocular vision 单眼
the angle of reflection = the angle of incidence
At the front of the head Location of the eyes One on each side of the headSmall Size of the field of vision Very largeLarge area of overlapping fields
Overlapping fields of vision Small area or no overlapping area
Can estimate distance accurately
See things in three dimensions
Importance of vision
Can see predators in all directions
Cannot judge distance accurately
Tigers, owls, human beings Examples Pigeons, rabbits, cows, fish
1.6 Sound and Hearing
Production and Transmission of Sound
1. Sound is produced by vibrations.2. When a sound is produced, kinetic energy is changed into sound energy.3. Sound can travel through solids, liquids and gases, but cannot travel through a vacuum.
Stereophonic Hearing
1. Stereophonic hearing is hearing with both our ears.
Defects of Hearing听觉的缺陷
1. Our ears can only hear sounds which have a frequency of about 20 Hz to 20 000 Hz.2. Some people use hearing aids such as earphones and stethoscopes.
1.7 Responses to Stimuli by Plants
Phototropism 向光性
1. Shoots grow towards light, showing positive phototropism.
2. Roots grow away from light, showing negative phototropism.
Hydrotropism 向水性
1. Roots grow towards water, showing positive hydrotropism.
2. Shoots grow away from water, showing negative hydrotropism.
Geotropism 向地性
1. Shoots grow upwards against gravity, showing negative geotropism.
2. Roots grow downwards towards gravity, showing positive geotropism.
Thigmotropism 向触性
1. Some plants with soft stems climb up a support when they touch it.
2. This response to touch by plants is called thigmotropism.
Nastic movement / Seismonastic reponse
1. The leaves of the mimosa plant close up when they are touched.
2. This response to touch is called a nastic movement or a seismonastic response.
3. A seismonastic response helps to protect the plant from injury.