人體的奧秘 - 你「聽」緊歌？

目錄
(1)基本既心臟介紹
lihkg.com/thread/649350

(2)基本既肺臟介紹
lihkg.com/thread/652225

(3)基本既腎臟介紹
lihkg.com/thread/665504

(4)基本既胃部介紹
lihkg.com/thread/673704

(5)基本既小腸介紹
lihkg.com/thread/685309

(6)基本既大腸介紹
lihkg.com/thread/690908

(7)基本既肝臟介紹
lihkg.com/thread/696439

(8)基本既胰臟介紹
lihkg.com/thread/700041

(9)基本既骨頭介紹
lihkg.com/thread/714062

(10)基本既肌肉介紹
lihkg.com/thread/744825

(11)基本既胸腺介紹
lihkg.com/thread/747138

(12)基本既脾臟介紹
lihkg.com/thread/752658

(13)基本既皮膚介紹
lihkg.com/thread/758234

(14)基本既陰莖 & 睾丸介紹
lihkg.com/thread/765959

(15)基本既陰道 & 卵巢介紹
lihkg.com/thread/775490

建議由第一期開始慢慢睇
想睇最新目錄請自行起底去最新個post
歡迎留言 一齊討論 你問我唔一定會答
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Try to feel the world, the yelling sound of kids in the playground, the 'lup-dup' heartbeat, the running computer. What a peaceful moment. And all of them is coming from your hearing organ, ears.
May埋對眼，感受一下，遠處細路既叫聲；心臟既跳動；電腦既運行，依一刻係幾咁既平和。而依一切，都係由耳朵 (ear) 帶比你既。

Ear is like a microphone, translating the air vibration to a language that the brain can understand. But what is the language of the brain? How ears do their jobs? Let's find out.
耳朵就好似一個咪，將空氣既震動轉換成大腦明白既語言。但係乜野係大腦語言？耳朵係點樣做到既？一齊搵出黎啦。
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Start with the overview of the ear.
由成個耳朵既結構開始講起。

The ear can be divided into 3 parts, the outer ear, the middle ear and the inner ear.
(i) The outer ear consists of 3 parts, the external ear (or pinna), the ear canal (or acoustic meatus) and the tympanic membrane (or eardrum). They transmit sound wave.
(ii) The middle ear consists of 3 ear bones (or ossicles), they are the malleus, the incus and the stapes. We can simply define their works by their names. The malleus hammers the incus and transmits the vibration to the stapes that nailed into the inner ear. This process magnifies the vibration for about 20 times stronger.
耳朵可以分成3個部分，外耳、中耳同埋內耳。
(一) 外耳 (outer ear) 又可以再細分做3個部分：耳殼 (pinna)、耳道 (ear canal) 同埋耳膜 (eardrum)。佢地負責傳遞空氣既震動，亦即係聲波。
(二) 中耳 (middle ear) 基本上係由3舊骨頭仔組成既，分別係鎚骨 (malleus)、砧骨 (incus) 同埋鐙骨 (stapes)，依D耳骨 (ossicle) 個名就已經講佢地既作用。鎚骨就係一個類似鎚仔既骨，將接收到既聲波敲落舊砧骨到，砧骨再將聲波傳落個粒已經固定左係內耳既鐙骨到。依3舊骨除左會傳遞聲波之外重會將聲波放大20倍左右。

(iii) The inner ear simply equals to the bony labyrinth and the structures inside. I'll explain what exactly is a bony labyrinth later on. The bony labyrinth included a structure you may be more familiar with, the cochlea, where the sound waves are translated into the language of the brain. There are cranial nerves connected to the cochlear which deliver the language of the brain.
(三) 內耳 (inner ear) 基本上係指一舊由骨頭搭出黎既「迷宮」(bony labyrinth)，之後會再詳細講依個「迷宮」既結構。「迷宮」既其中一個部分可能你會更加熟識，叫做耳蝸 (cochlea)。耳蝸就係將聲波翻譯做大腦語言既地方，佢連接住腦神經 (cranial nerves)。而腦神經就係用黎傳遞大腦語言。
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Let's take a look at the bony labyrinth.
黎睇下個「迷宮」，或者可以直接叫佢做內耳，都一樣。

The figure shows the whole structure of the bony labyrinth. This maze-like structure consists of 3 parts, the semicircular canal, the vestibule and the cochlea. They are all filled with fluids.
(i) Semicircular canals are responsible for the balance of the body. The 3 canals, anterior, posterior and lateral canals, detect different positioning of the head with mechanical receptors inside. It helps the brain to understand the positioning of the head.
張圖就係「迷宮」既全貌。成個「迷宮」主要可以分做3大部份：半規管 (semicircular canal)、前庭 (vestibule) 同埋耳蝸 (cochlea)，裡面全部都係液體。
(一) 半規管幫助我地平衡，透過提供反映身體姿勢既數據。我地有3條半規管，相對位置係前面、後面同埋側邊。身體透過感應依3條半規管係唔同位置下既唔同液壓，話比個腦知我地依家頭部既姿勢，當然都係用大腦語言。

(ii) The vestibule assists semicircular canals on balancing. Besides, it is also responsible in hearing. The oval window, which is nailed with the stapes of the middle ear, receives sound waves from stapes and deliver them to the cochlea through the fluid inside. Sound waves go through the whole cochlea and back to the round window which is inferior to the oval window and get out of the bony labyrinth. (Both end of a delivery duct need to be opened so that sound waves can be transmitted through the delivery duct. That's physics.)
(二) 前庭同樣係幫助平衡，不過佢都負責我地既聽覺。橢圓窗 (oval window) 就係鐙骨固定既位置，佢透過鐙骨接收聲波，再將聲波帶去耳蝸，透過佢裡面既液體。聲波經過成個耳蝸，再由落小小既小圓窗 (round window) 出番黎。(小圓窗令到耳蝸依個傳遞聲波既管有頭尾開口，因為一條管要頭尾都有開口聲波先容易傳遞，物理既野就唔多解釋啦。)

(iii) The cochlea is a snail structure of the bony labyrinth. As mentioned, the cochlea is where the sound waves are translated into the language of the brain. As a lower pitch of the sound wave represents a lower frequency, it is harder to be detected. So the nerve cells near the helicotrema, the apex of the cochlea, is responsible for low-frequency sound waves detection, vice versa.
(三) 耳蝸就係「迷宮」結構裡面類似蝸牛既部分啦。都講過啦，耳蝸就係聲波翻譯成大腦語言既地方。低音代表低頻率，姐係會比較難感應，所以呢係蝸頂 (helicotrema) 附近既細胞就係負責低音既感應，離蝸頂越遠就感應越高既音。
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This is a cross-section of the cochlea for you to have a further appreciation of the bony labyrinth.
再睇深小小個耳蝸，依張係耳蝸其中一處既橫切面。

Inside the bony labyrinth, there is a membranous labyrinth. In fact, the membranous labyrinth itself is also a closed system that resembles the shape of the bony labyrinth. The fluid inside the membranous labyrinth is called the endolymph while the fluid surrounds the membranous labyrinth is called the perilymph. The main difference between the 2 fluids is the concentration in electrolytes, where the endolymph has a higher concentration in electrolytes than the perilymph. It is like the difference between Pocari and tap water, where endolymph is Pocari.
可以見到，骨頭「迷宮」包住左1條管，而依條管又冇將成個內腔佔用曬，結果就將耳蝸裡面分開左做3個空間。其實條管本身都幾長下，係骨頭「迷宮」入面自己又形成左一個類似既「迷宮」，所以佢都比人叫做「迷宮」，不過係用膜做既 (membranous labyrinth)。係膜做既「迷宮」入面既液體呢就叫做耳內液 (endolymph)，而包住佢既呢就叫耳外液 (perilymph)。依兩隻液體既分別就好似「保礦力」運動飲品同水喉水既分別咁，耳內液好多電解質，耳外液就冇乜。

The portion of membranous labyrinth in the cochlea is called the cochlear duct, with itself surrounded by 2 ducts, the vestibular duct and the tympanic duct. Let's have some brief understandings on these 3 ducts.
(i) The vestibular duct begins at the oval window and finishes at the helicotrema.
(ii) The tympanic duct starts at the helicotrema and ends at the round window.
(iii) The cochlear duct is where the hearing cell, called the hair cell located. These hair cells in the cochlear duct detect the vibration from the vestibular duct & the tympanic duct, and then send the message to the brain through cranial nerves. The separating membrane from the vestibular duct is the vestibular membrane (or Reissner's membrane), while the side of the tympanic duct is called the basilar membrane.
黎介紹下依3個空間，膜「迷宮」係耳蝸既部分就叫做耳蝸管 (cochlear duct)，而隔離個兩個管狀空間呢就叫前庭管 (vestibular duct) 同埋鼓管 (tympanic duct)。
(一) 前庭管由橢圓窗開始去到蝸頂。
(二) 鼓管由蝸頂開始去到小圓窗。
(三) 耳蝸管就係感應聲波既細胞所在既地方啦，個D細胞叫毛細胞 (hair cell)。依D毛細胞係耳蝸管入面感應黎自前庭管同埋鼓管既震動，再將佢地翻譯成大腦語言，透過腦神經送番去個腦到。分開前庭管同耳蝸管既膜有另一個名叫前庭膜 (vestibular membrane)，而鼓管個邊呢就叫基底膜 (basilar membrane)。

I've mentioned the sound waves are being translated to the brain instead of directly shocking the brain. However, indeed, I didn't say anything informative to the language of the brain so it's time to answer the question at the beginning, 'what is the language of the brain?'.
成篇野我都係咁講「大腦語言」依個term。但係我一直都冇解釋佢係咩黎，所以呢，依家就黎解釋番一開始問落既問題啦。

Imagine you are holding a package of little magnets and a magnetic sensor. Let's say the magnetic sensor gives you the number '0.05 Tesla' for the magnetic field of the package. Then, you take some magnets out, and the reading of the magnetic sensor drops to '0.03 Tesla'. It is a noticeable change, isn't it?
想像一下你手上面揸住一袋磁石同埋一個磁力感應器，依家個感應器顯示「0.05特斯拉」。跟住你係袋入面拎走一D磁石，依家個感應器顯示「0.03特斯拉」。個感應器發現改變，再回應個改變，係咪？

And now you've learned the language of the brain. Hah? Yes, you are. The magnetic sensor represents the brain. The package of little magnets represents the nerve cell. The action of taking away magnets from the package represents the physiological changes of the cells. When the physiological change is significant, it is called a nerve impulse, which is the language of the brain. When your brain receives a nerve impulse, you would notice, like the magnetic sensor notices the change in the magnetic field.
所以你已經學識左「大腦語言」啦，就係咁簡單。磁力感應器代表個腦；磁石既袋代表神經細胞 (nerve cell)；拎磁石依個動作代表細胞既改變。當個改變係明顯既時候，我地就叫佢神經信號 (nerve impulse)，而大腦所用既語言就係神經信號，大腦收到神經信號，你就會知道，就好似個磁力感應器可以感應附近既磁場咁。
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Let's look into the physiological change in producing a nerve impulse. The whole change can be divided into 2 categories, the preparation and the action.
詳細D咁睇下身體發出神經信號既生理改變啦，基本上分可以分做2個階段：準備階段同埋行動階段。

It is the figure showing how the preparation is done. Although the package, the magnetic sensor and the action of taking away magnets are representing other things, those tiny dots are really little magnets. There are 2 kinds of magnets, demonstrated in 2 different colors. The red one is called the sodium (short-form: Na) and the green one is called the potassium (short-form: K). Don't worry too much about those naming, just like you and I, they need a name! They are simply the same thing besides the name, at least they give out identical forces, 1+ charged in chemical level. (They are very similar even in chemistry. )
(1) In normal condition, if the cell membrane is permeable to Na & K (actually not permeable), Na & K would evenly distribute in the space according to the law of physics, called the Fick's law.
張圖就係發出神經信號既準備階段。雖然磁力感應器、拎磁石依個動作同埋個袋都係比喻緊其他野，但磁石就係真既，圖中既一點點就係磁石。有2種磁石，分別係用紅點代表既鈉 (sodium, Na) 同埋用綠點代表既鉀 (potassium, K)。唔洗太在意D命名，D磁石同我地一樣，都需要一個名。不過依2種磁石除左名之外，都非常之似 (但身體就分辨到，其實幾犀利)，釋放差唔多既力 (化學上叫1+)。
(一) 係正常既情況下，假設細胞膜可以比鈉同鉀穿過 (實際係唔得)，鈉同鉀會分別咁係空間平衡分佈。

(2) Add in some Na-K pumps into the system, which is responsible for pumping K into the cell and pumping Na out of the cell, powered by the energy currency ATP. As long as there are ATPs, Na-K pumps are always working. As the cell membrane is actually impermeable to Na & K, if there are the present of Na-K pumps, there are more K inside the cell and more Na outside the cell. In the other words, The concentration of K is higher inside the cell, while the concentration of Na is lower inside the cell.
(二) 跟住係個系統加入鉀鈉泵 (Na-K pump)。鉀鈉泵既作用好簡單，以能量貨幣 (ATP) 推動，係將鉀泵入細胞，再將鈉泵出細胞，只要有能量貨幣，鉀鈉泵就會不停咁重複運作。因為細胞膜唔比鈉同鉀穿過，加上鉀鈉泵 (重有能量貨幣) 既存在，就會慢慢形成一個情況係細胞入面既鉀多過出面，而鈉就相反。換句話講即係細胞內既鉀濃度高過細胞外，同埋細胞內既鈉濃度低過細胞外。

Lm支持

(3) Add in some K channels into the system, which is an exit that only allows K to pass through. Applying the Fick's law, K will try to achieve even distribution through K channels, so K goes down the concentration gradient, i.e. from inside to outside the cell. Now, the concentration of K inside is equal to the outside and concentration of Na inside is less than the outside. Overall, there is a difference in concentration of Na & K. It is a difference that can potentially get something done so the difference is called the membrane potential, which is around -70 millivolt in nerve cells. (In case you are confused by the negative sign, it is just a problem of the focus. If you put the focus on the outside environment, that's 70 millivolts! ) In fact, there is always a membrane potential in every living cells (but the voltage is different). That's why the membrane potential is also called the resting potential.
(三) 跟住就再係個系統加入鉀通道 (K channel)。鉀通道都好簡單，就係鄭係容許鉀通過既一條路。根據物理，鉀會希望透過D通道達到細胞內外既平衡分佈，所以鉀又會走番出去細胞外面。理想既結果係鉀因為依D通道又變番做平衡分佈，但唔好唔記得，我地重有鈉既唔平均，所以結果就係建立左細胞內外鈉同鉀既總濃度差。因為依個差異可以做到一D野，就好似拉緊左既橡筋咁，所以依個細胞內外既差異就係勢能 (potential energy)，而因為個差異既分界點係個細胞膜，所以依種勢能又叫細胞膜電勢 (membrane potential)，而普通神經細胞既細胞膜電勢大概有-70毫伏左右 (如果你唔明點解可以係負數，其實只係焦點與角度既問題，如果你將個焦點放係細胞外既環境，就係70毫伏啦)。其實唔同既細胞長期都會有細胞膜電勢 (唔同強度咁解)，所以細胞膜電勢又叫做默認電勢 (resting potential)。

It is the figure showing how the action is done. The resting potential is constantly building up.
準備好就到行動階段啦。默認電勢將會一直存在。
(1) Add in some voltage-gated Na channels into the system, which is an entrance that only allows Na to pass through. It is always closed unless the resting potential changes significantly to the threshold level (It is around -55 millivolt for the nerve cell). If there are no stimulations that would cause the change in the resting potential, everything is fine.
(一) 再係個系統到加入鈉通道，不過今次唔同小小，係一個會感應電勢既鈉通道 (voltage-gated Na channel)。當電勢去到特定數值，通道就會打開，容許D鈉通過。而神經細胞既特定數值通常係-55毫伏左右。如果冇任何既刺激改變個默認電勢，咁就乜事都冇。

(2) But if there is a significant stimulation which changes the resting potential of the cell to the threshold level, voltage-gated Na channels would open. Applying the Fick's law, Na will try to achieve even distribution through Na channels, so Na goes down the concentration gradient, i.e. from outside to inside the cell. Because of the Na flood, the resting potential at threshold level further increase. The difference in concentration of Na & K between inside and outside is now changed. But still, there is a difference, and this difference is getting called the action potential (The action potential is any voltage higher than the threshold level of voltage-gated Na channels). The cells at action potential level would be noticed by other nerve cells and of course the brain. That's why an action potential is also called a nerve impulse.
(二) 但如果有刺激明顯咁改變個默認電勢去到開放鈉通道既特定數值，佢就會開啟。根據物理，鈉會希望透過D通道達到細胞內外既平衡分佈，所以鈉又會走番出去細胞入面。就係因為鈉既湧入，令到個電勢再度上升。雖然上升左，鈉同鉀既濃度差距細左，但都係有差距，而依一隻高過開放鈉通道特定數值既勢能，又叫做動作電勢 (action potential)。處於動作電勢既神經細胞會觸發附近神經細胞進入動作電勢，最終將動作電勢送去大腦。所以動作電勢又叫做神經信號。
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Back to the ear, let's follow the process of hearing one by one.
(1) Air vibration, or vibration of other media like the water.
(2) The vibration goes through the outer ear, magnifies in the middle ear and sends to the inner ear, the bony labyrinth.
(3) The vibration enters the bony labyrinth at the oval window and is delivered by the perilymph in the cochlea.
(4) The stereovilli of hair cells in the cochlear duct receive the vibration and move. These movements trigger a series of physiological changes and alter the resting potential of the hair cell.
番番去隻耳仔，黎睇下我地係點樣「聽」到聲音。
(一) 首先梗係有空氣震動，當然都可以係其他媒介既震動，例如係水，依D震動又叫做聲波。
(二) 聲波走入去我地既外耳，係中耳被放大，再送入內耳。
(三) 聲波透過橢圓窗入去內耳既前庭，透過耳外液送入耳蝸。
(四) 係耳蝸管入面，毛細胞既纖毛 (stereovilli) 因為聲波而郁動，依D郁動又會觸發一連串既生理改變，令到處於默認電勢既毛細胞提升電勢。

(5) If the resting potential rises high enough to the threshold level, the hair cell would further develop into the action potential level.
(6) Nerve cells in cranial nerves notice the action potential level of the hair cell. Those Nerve cells also change into the action potential level.
(7) The nerve impulse is finally sent to the temporal lobe of the brain and we hear the sound!
(五) 如果電勢提升到高過上限水平 (threshold level)，毛細胞就會進入動作電勢。
(六) 毛細胞既動作電勢觸發附近神經細胞既動作電勢。
(七) 一個傳一個，神經信號傳到去大腦既顳葉 (temporal lobe)，我地聽到聲音啦！
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假膠名回假膠野

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btw 上兩篇既野咁快完左既

耳機jj強勢留名

屌 我記得你XD

再講多幾次上「一」篇既野真係打10次飛機都唔掂