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CHAPTER 1 ~ THE WORLD THROUGH OUR SENSES 1.1 Sensory Organs and the Nervous Pathway Sensory organs Stimulus detected Main function Skin 皮皮 Touch, pain, heat, cold, pressure Organ for touch Nose 皮皮 Chemicals Organ for smell Tongue 皮皮 Chemicals Organ for taste Ear 皮皮 Sound Organ for hearing Eye 皮皮 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. 皮皮 Epidermis 皮皮皮 receptors,皮皮 touch receptor 皮 pain receptor. Stimuli receptors nervous impulses Sensation is nervous

Chapter 1 the World Through Our Senses

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World Through Our Senses

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Page 1: 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

Page 2: Chapter 1 the World Through Our Senses

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

Page 3: Chapter 1 the World Through Our Senses

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

Page 4: Chapter 1 the World Through Our Senses

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

Page 5: Chapter 1 the World Through Our Senses

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

Page 6: Chapter 1 the World Through Our Senses

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

Page 7: Chapter 1 the World Through Our Senses

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.