神經科學-神經,有問題?
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(2) 版權所有,請勿散佈. 4~14歲的小孩中,大約每1000人 有8個人會有這種危險的症狀發生!. 生物 vs. 無生物. 2.
(3) 版權所有,請勿散佈. Response to environment. Physical Factors: 辨識系統. Sound Light Heat Gravity. “接受器” Chemical Factors: Taste Odor Drugs. 3.
(4) 版權所有,請勿散佈. The Nobel Prize in Physiology or Medicine 2004 "for their discoveries of odorant receptors and the organization of the olfactory system". Richard Axel. Linda B. Buck. USA. USA. Columbia University New York, NY, USA; Howard Hughes Medical Institute. Fred Hutchinson Cancer Research Center Seattle, WA, USA; Howard Hughes Medical Institute. b. 1946. b. 1947. Olfactory tract Olfactory bulb Nasal cavity. Bone. ~5 million olfactory neurons are located in the olfactory epithelium on the wall of the nasal cavity. 4.
(5) 版權所有,請勿散佈. The cilia of the olfactory neuron have specific receptors for odorants & the signal transduction machinery needed to amplify sensory signals. Olfactory bulb 4. the signals are transmitted to higher regions of the brain. bone Olfactory receptor cells. 3. the signals are relayed in glomerus. 2. Olfactory receptor cells are activated & send electrical signals. 1. Ordorants bind to receptors. 5.
(6) 版權所有,請勿散佈. 神經細胞 是沙咪碗糕呢?. 6.
(7) 版權所有,請勿散佈. 一般來說,每個神經元的 寬度大約是10微米,相當 的小。也就是說一公分的 長度相當於1000個神經元 並排,那一千億個神經元 細胞有多長呢?並排起來 可以達到1000公里那麼遠 呢!. 100,000,000,000 1300 克 體重的 2%. Neurons are the oldest and longest cells in the body !. 神經細胞和身體其他的細胞有何差異呢? 神經細胞有特殊的形狀及大小. Neurons have diverse forms 神經細胞彼此會藉由形成突觸而互相聯繫 Neurons communicate with each other at synapses 神經細胞具有產生細胞電性差異的能力 Neurons have ability to generate electricity 神經細胞具有極高的代謝活動 Neurons have high rate of metabolic activity 神經細胞具有有效的運輸系統 Neurons have an efficient transport system …..族繁,不及備載。. 7.
(8) 版權所有,請勿散佈. 樹突與細胞體 主要負責接收外界的傳入訊號. 軸突 主要負責將興奮的訊號傳遞到軸突末梢. 軸突末梢 主要負責將興奮的訊號傳遞給後 面的動器(如另一個神經細胞或 肌肉細胞). The Somato-dendritic Tree 細胞體形狀:多樣化的 錐狀(大腦皮質及海馬回中的 Pyramidal neurons) 軟圓形(小腦皮質的 Purkinje neurons) 紡垂狀的(pallidal complex 中的神經 元細胞) 星狀的(脊髓中的 Motoneuron) 一般來說,每個細胞體約可延伸出1~9條一級樹突,而後每條一級樹突 在繼續分支而形成樹突樹(dendritic tree);樹突的形狀較不規則,剛 由細胞體分出時最粗,然後隨著延伸的距離越長會便得越細。 在樹突樹突之上可以看到許多向外突出的卵圓形突出物,稱為dendritic spine,每個神經元細胞上dendrite spine 的數目不盡相同,有的高達 4萬~10萬個(spiny),有的則只有極少數的dendrite spine (smooth)。. 8.
(9) 版權所有,請勿散佈. The Dendritic Spine. The Dendrite Spine. 9.
(10) 版權所有,請勿散佈. THE. Dendrite Spine. increase the surface area available for new synapses to form. Dendritic Spine. 在樹突樹突之上可以看到許多向外突出的 卵圓形突出物,稱為dendritic spine,每個 神經元細胞上dendritic spine 的數目不盡 相同,有的高達4萬~10萬個(spiny),有的 則只有極少數的dendritic spine (smooth)。. 10.
(11) 版權所有,請勿散佈. Normal and Abnormal Dendrite. Long-term potentiation (LTP) or learning induces morphological changes in dendritic spines. Most excitatory synapses in the brain terminate on. dendritic spines. 11.
(12) 版權所有,請勿散佈. Morris water maze (by Richard Morris): spatial memory Hidden platform Wading pool. Before learning. After learning. LTP (1 hr later). 12.
(13) 版權所有,請勿散佈. The Somato-dendritic Tree is the neuron’s Receptive Pole 功能: 接受外來的訊號,有的神經甚至可與傳入神經建立高達一萬個突觸!! 整合外界所傳來的興奮性(EPSP)或抑制性(IPSP)訊號,若訊號總和 超過一個特定的閥值,則會引發動作電位。. Soma:. (neuronal cell body). the metabolic center 與身體其他細胞具有相同 的胞器,如細胞核、高基 氏體、核糖體,粒腺體、 內質網等等,可合成蛋白 質,為細胞的代謝中樞。. 13.
(14) 版權所有,請勿散佈. The Axon & axonal collaterals 和樹突比較起來,軸突具有平滑 的外觀,且整條軸突自soma 起 始端到末梢的直徑很均一。軸突 的長度隨著神經的種類差異很大, 在某些神經其長度甚至可長達一 公尺以上。 有些神經的軸突會被膠質細胞(glia cell)所包覆而形成髓峭,軸突 在兩段髓峭間未被包覆的區域稱為蘭氏結(Nodes of Ranvier)。 神經軸突的末梢會特化成synaptic buttons,藉由這些特化組織,軸突 可以和其他神經或標的細胞(如肌肉細胞)形成突觸(synapse),達 到聯繫的作用。. 軸突傳出. 1000 1. 樹突傳入. 14.
(15) 版權所有,請勿散佈. 113Years Old. VS.. 15.
(16) 版權所有,請勿散佈. Presynaptic Nerve Terminal Synaptic Cleft. Postsynaptic Muscle Cell. The Axon & axonal collaterals are the neuron’s Transmitter Pole 功能: 誘發動作電位(Trigger action potential) 以不失真的方式來將動作電位傳遞到神經末梢 特化的軸突末端可以感應動作電位的來臨而釋放出神經傳遞物質 來影響突觸後的神經或標的細胞. 16.
(17) 版權所有,請勿散佈. ~動作電位的產生~. 神經活性的誘導係 因為神經本身細胞膜 電位由於細胞外及細 胞內各種離子經由離 子通道的流動所引發 而造成動作電位 動作電位: 去極化:鈉離子流入 細胞內 再極化:鉀離子流出 細胞外. 17.
(18) 版權所有,請勿散佈. “Ion channel” is….. Hodgkin & Huxley, 1950s …the fluxes of Na+ and K+ ions are through “holes” in the membrane. Awardees of the 1963 Nobel Prize. The Nobel Prize in Physiology or Medicine 1963 "for their discoveries concerning the ionic mechanisms involved in excitation and inhibition in the peripheral and central portions of the nerve cell membrane". 18.
(19) 版權所有,請勿散佈. The rapid opening of voltage-gated Na+ channels allows rapid entry of Na+, moving membrane potential closer to the Na+ equilibrium potential (+60 mv). The slower opening of voltage-gated K+ channels allows K+ exit, moving membrane potential closer to the K+ equilibrium potential (-90 mv). 神經細胞如何能產生訊號以便將所接收的訊號往下傳達呢?. 19.
(20) 版權所有,請勿散佈. Ca. 2+. Ca2+. Na +. Na. +. K. K+. +. 大體來說,離子通道對離子的通過是具有選擇性的。如: Na+ 離子通道打開時對 Na+ 的通透性要比 K+ 高10~20倍;而 K+ 離子通道打開時對 K+ 的通透性要比 Na+ 高100倍以上。. What makes a channel selective? Pore size?. 20.
(21) 版權所有,請勿散佈. 酵素藉由形成不同的結合位來辨識其受質,離子通道用什 麼方法來辨識各種離子呢? 例如具有相同形狀與相同電荷的 Na+ 及 K+ 呢? ACh receptor pore. Na+ channel K+ channel pore pore H2O. Na+. K+. (0.4 nm) K+ channel,可以讓K+ (2.66) 通過, 卻不能讓Na+ (1.9) 通過呢?. Molecular Neurobiology, P.88. Selectivity cannot be based solely on the. Diameter of the ion. 21.
(22) 版權所有,請勿散佈. Ions in solution are surrounded by waters of HYDRATION. 鹽 (NaCl). 水 水分子 (H2O). 氫鍵 Hydrogen bonds. 因水分子氫鍵的影 響而使得Na與Cl 間的離子鍵被打斷. 離子鍵(ionic bond) Na與Cl之間因離子鍵形 成而結合. 22.
(23) 版權所有,請勿散佈. The ease with which an ion moves in solution depends on its size together with the shell of water surrounding it Ions in solution are surrounded by waters of hydration Small ions have stronger effective electric fields Smaller ions attract water more strongly The smaller the ion, the lower its mobility. Na+ channel pore. For K+ 2.66 + n*2.8 > 3.3 (K channel). K+ channel pore H2O. Na+. K+. For Na+ 1.9 + n*2.8 > 4 (Na channel) Principal of Neural Science p.106. The Nobel Prize in Chemistry 2003 "for discoveries concerning channels in cell membranes". Peter Agre. Roderick MacKinnon. USA. USA. Johns Hopkins University School of Medicine Baltimore, MD, USA. Rockefeller University New York, NY, USA; Howard Hughes Medical Institute. b. 1949. b. 1956. 23.
(24) 版權所有,請勿散佈. In 1998 Roderick MacKinnon for the first time determined at high resolution the structure of an ion channel. By showing what the protein looked like at the atomic level, he also realized how it functions.. 24.
(25) 版權所有,請勿散佈. 離子在水中會有水合效應,此 時size 比孔道大故通過孔道時 必需先去水合(速率>109/sec). 離子通道的選擇性 決定於孔道的大小以及 孔道中與離子的結合位. 離子與離子通道中的特定結合 位結合. 離子濃度梯度與電荷差異所造 成的驅動力克服打破離子與結 合位的鍵結能,而使得離子離 開結合位通過孔道並再次水合. Na+ binding site. K+ Extracellular side Membrane Cytoplasmic side. Na+. Na+. Principal of Neural Science p.106. 神經細胞如何能產生訊號以便將所接收的訊號往下傳達呢?. 25.
(26) 版權所有,請勿散佈. +. In case of K channel… Na+ binding site. Na+ K+. Na+. Longest axon of a neuron= ~15 feet (Giraffe, from toe to neck). 26.
(27) 版權所有,請勿散佈. Input Zone Dendrites and Cell body. Nucleus Trigger Zone Axon hillock. Conducting Zone Axon (may be from 1mm to more than 1m long). 神經非常的長,當神經受刺激而興奮時, 如何將這種興奮性傳那麼遠的距離而不. 失真呢?. Output Zone Axon terminals. “The Active Response “. 能量在傳遞過程中會 逐漸喪失!. 27.
(28) 版權所有,請勿散佈. 不失真?. 28.
(29) 版權所有,請勿散佈. Passive Current Flow in an Axon Positive current injected. Neuroscience p.62. Setting off firecrackers. 29.
(30) 版權所有,請勿散佈. Active Responses to large depolarizing stimuli. More Positive current injected. Neuroscience p.63. The Domino Effect. 30.
(31) 版權所有,請勿散佈. The Neuron p.58. Active response-- 鄰近的Na+ channel打開-- regenerate energy Passive response-- 鄰近的Na+ channel不打開--No regenerate energy. 神經軸突所具有的 active spread 特性以及當他受到超過閥值的 刺激後遵循 all or none 定律來引發動作電位的結果,使得神經興 奮後可以將這種興奮性不失真的傳遞很遠,直到神經末梢為止。. All or None 動作電位的定律. 31.
(32) 版權所有,請勿散佈. 當對神經的刺激強度高過某一臨界值時,神經 軸突對此刺激的反應會由被動反應轉成主動反 應,threshold 的存在可以濾掉較小、突發性 的膜電壓波動而不會產生AP,如此可以防止 不具意義的神經興奮而造成誤傳。. 為什麼要有”Threshold”. 從接受刺激引發動作電位開始至 達到動作電位波峰所需的時間, 會受到刺激強度大小所影響. Delay latency. Delay latency. 既然所產生的動作電位他們的amplitude 都一樣大,那神經如何區分所受刺激的強度大小呢?. 32.
(33) 版權所有,請勿散佈. 刺激強度和動作電位的amplitude無關,但會影響AP的 delay latency 及refractory period. 較高的刺激強度可以在同一時間內誘導神經產生較多的動作電位, 也就是神經被興奮的頻率增加了. Axon hillock. 33.
(34) 版權所有,請勿散佈. 34.
(35) 版權所有,請勿散佈. 青蛙的心臟其心跳 速率會受迷走神經所 控制,刺激迷走神經 其心跳速率會減慢 迷走神經受刺激之 後會釋放出神經傳遞 物質Acetylcholine 來抑制心臟的收縮速 率. The Nobel Prize in Chemistry 1936 "for their discoveries relating to chemical transmission of nerve impulses“. Sir Henry Hallett Dale. Otto Loewi. United Kingdom. Austria. National institute for Medical Research London, United Kingdom. Graz University Graz, Austria. 1875~1968. 1873~1961. 35.
(36) 版權所有,請勿散佈. 外加 ACh可以比擬刺激迷走神經 所造成的心跳速率變慢現象,顯 示 ACh 是刺激迷走神經時所釋 放出來而改變心跳速率的化學物 質。. Stimulate vagal nerve. Increase AP interval. AP is abolished. 36.
(37) 版權所有,請勿散佈. 當突觸前神經受到刺激時在突觸會有神經傳遞物質釋放出來. 動作電位經Axon 傳 到神經末梢造成神經 末梢鈣離子通道的打 開. 鈣離子流入並造成突 觸泡與細胞膜融合破 裂而釋放出神經傳遞 物質. 神經傳遞物質結合並打 開離子通道,造成離子 流動而促進或抑制突觸 後細胞的興奮性. 神經末梢突觸泡的循環. Endosome. Targeting Docking Priming. Fusion. Endocytosis. 37.
(38) 版權所有,請勿散佈. Dock the Targeted Vesicles at Active Zone & Prime Them for Fusion. SNARE complex SNAP-25 Syntaxin Synaptobrevin. synaptophysin. synaptobrevin. N-Sec1 syntaxin. SNAP-25 synaptotagmin. 38.
(39) 版權所有,請勿散佈. SNARE complex. SNARE complex (Synaptobrevin, syntaxin, SNAP-25). Synaptotagmin & Ca2+ influx. 肉毒桿菌毒素(Botulinum toxin) 視力減退、眼皮下垂、 瞳孔散大、語言障礙、 吞嚥障礙、唾液分泌障 礙,嚴重時會導致呼吸 肌受到抑制呼吸衰竭而 死亡. Clostridium botulinum. 39.
(40) 版權所有,請勿散佈. BOTOX® Cosmetic Botulinum toxin type A. Bioactive peptides: signaling the future The current understanding of peptides in cosmetic skincare is generally tied to applications for:. Collagen stimulation “Botox-like” wrinkle-smoothing effects Journal of Cosmetic. 40.
(41) 版權所有,請勿散佈. Botox-like via SNARE inhibition. (acetyl hexapeptide-3). 41.
(42) 版權所有,請勿散佈. Int j cosmet sci 2002;24: 303–10. Dock the Targeted Vesicles at Active Zone & Prime Them for Fusion. SNARE complex SNAP-25 Syntaxin Synaptobrevin. Botox-like via SNARE inhibition. 42.
(43) 版權所有,請勿散佈. 汞金屬離子中毒事件 時間:1960年左右 地點:日本漁村Minamata Bay 症狀:走路不穩、躺在床上抽動、智商下降等 等 汞離子:日光燈、電池…… 鉛離子:油漆、報紙油墨、汽油….. 兒童血鉛含量高於歐日 調查單位:高雄醫學大學 取樣來源:高雄市32所小學三年級某班共935人 結果: 1. 血鉛濃度平均值 5.5微克/100毫升,高於臨界質2.5微 克/100毫升。 2. 學童血中鉛含量濃度越高者在班上成績名次越後面, 尤其與國語、社會等記憶性課程相關性顯著。 鉛的危害: 1. 鉛進入人體以後,90%以上沈積及累積在骨骼系統 中,稍後可慢慢釋放到血液中,其半衰期達20年。 2. 對兒童最大的影響是中樞神經的發育。. 43.
(44) 版權所有,請勿散佈. Cone snail w-Conotoxin. funnel web spider (Agelenopsis aperta) Agatoxin. 當突觸前神經受到刺激時在突觸會有神經傳遞物質釋放出來. 動作電位經Axon 傳 到神經末梢造成神經 末梢鈣離子通道的打 開. 鈣離子流入並造成突 觸泡與細胞膜融合破 裂而釋放出神經傳遞 物質. 神經傳遞物質結合並打 開離子通道,造成離子 流動而促進或抑制突觸 後細胞的興奮性. 44.
(45) 版權所有,請勿散佈. 可以結合神經傳遞物質 而產生作用的“接受器”. 運動神經末梢 神經傳遞物質. 可以水解神經傳 遞物質而終止其 作用的酵素. 肌肉細胞. 45.
(46) 版權所有,請勿散佈. Nicotinic ACh Receptor (acetylcholine). 46.
(47) 版權所有,請勿散佈. Strychnos Toxifera. curare. 神經傳導物質之去活化 擴 散. 酵素代謝. 回 收. ACh E A. Ch. 47.
(48) 版權所有,請勿散佈. 時間:1995年3月20日 地點:東京地下鐵車站 經過:奧姆真理教恐怖份子釋放沙林毒氣 結果:12人死亡, 超過5000人中毒身體不適. 時間:1938 年;世界第二次大戰 地點:德國 人物:德國科學家 Schrader, Ambros, Ririger 及 van der Linde首次製造 特性:無色無味 致死劑量: 吸入0.075~0.1克;15分鐘內死亡! (相當於一顆米大小). 皮膚接觸1~1.7克;2分鐘內死亡!. 48.
(49) 版權所有,請勿散佈. 神經毒氣沙林作用機轉 神經末梢 E. A. Ch. E. ACh. S. ACh. ACh ACh. ACh 接受器. 神經毒劑中毒症狀 肌肉麻痺、呼吸衰竭 視覺模糊、噁心、嘔吐、盜汗 頭痛、昏迷、癲癇發作. 49.
(50) 版權所有,請勿散佈. Atropine. ACh 接受器. 50.
(51) 版權所有,請勿散佈. 影響神經間訊息傳遞而造成毒性的生物. 影響神經間訊息傳遞而造成毒性的生物. 51.
(52) 版權所有,請勿散佈. Switzerland based. SYN®-AKE is a small peptide that mimics the activity of Waglerin 1, a polypeptide that is found in the venom of the Tropidolaemus wagleri (韋氏竹葉青).. 啥咪! 蛇毒也能治皺紋?. 52.
(53) 版權所有,請勿散佈. Torpedo Califonica. 600 V !. 53.
(54) 版權所有,請勿散佈. Electrocyte cells from the electric organ. 54.
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