responses(引起反应)

1、Signal Transduction Mechanisms (I) The Nervous System Understanding Membrane Potential Electrical Excitability The Action Potential Synaptic Transmission Integration and Processing of Nerve SignalsThe Nervous SystemThree functions:Collects informationProcesses that informationElicits responses（引起反應）

2、Nervous system:Central nervous system （中樞神經系統）Brain and spinal cord- sensory and motor cellsPeripheral nervous system（周邊神經係統）Somatic（軀體）nervous system Control the skeleton muscleAutonomic（自主）nervous system Control the cardiac muscle and smooth muscle在造成壓力的緊急的狀況下，我們還得去選擇迎戰或潰退(逃跑)在處於休息和 消化非緊急的狀態下。 交感神

3、經系統交感神經系統 是一個陽光普照，舒爽的日子，你悠哉地在公園散步。突然，一隻發怒的熊出現在前面。你會蓄勢放手一搏，還是轉身逃走？這就是搏鬥或是逃跑的反應。在這種情況下，你的交感神經活化血壓上升，心跳加快，消化作用減慢，因而得以應付能量之消耗。 交感神經系統的另外兩個特點：交感神經系統的神經節突觸係以乙醯膽鹼（acetylcholine）來當神經傳導素；投射至目標器官上的節後神經元突觸則利用腎上腺素（norepinephrine）為神經傳導素。副交感神經系統副交感神經系統 舒適，晴朗的一天.你在公園悠哉地散步。 此時，不管怎樣，你決定要坐在自己帶的椅子裡放輕鬆。這就是所謂的休息和消化狀態。此時

4、副交感神經開始運作血壓降低，心跳減緩，啟動消化作用而得以儲存能量。 來自延腦或脊髓的節前神經纖維會投射到非常靠近標的器官的神經節並形成突觸。這個突觸所使用的神經傳導素為乙醯膽鹼（acetylcholine）。而節後神經元則由這種神經節投射到標的器官並在末端釋出乙醯膽鹼（acetylcholine）。 Neurons（神經元）（神經元）- divided into three types Sensory neurons(感覺）感覺）: vision, smell, touch Motor（運動）（運動） neurons: transmit the signals from CNS to the

5、muscles or gland Interneurons（中間神經原）（中間神經原）: process signals received from other neuronsThe Nervous System Glial cells (神經膠質細胞神經膠質細胞) ：the most abundant types of cell in the CNS Microglia (小神經膠質細胞小神經膠質細胞) : phagocytic cells- fight for infection and remove the debris Oligodendrocytes (少突神經膠質細胞少突神經膠質細

6、胞): form insulating the myelin sheath around neurons of the CNS and peripheral nerves Astrocytes (星狀膠細胞星狀膠細胞): 圍繞在腦部微血管外圍，形成血腦屏障(blood-brain barrier)，可限制大部分的物質進入腦部 Schwann cells (神經鞘細胞神經鞘細胞): form insulating the myelin sheath (髓鞘) around neurons of the CNS and peripheral nervesThe functions of glial

7、 cellsRepair and maintenance. Glial cells attempt to keep neurons heathly. They produce new myelin(髓磷酯) when it become damaged (oligodendroctyes) and lay down scar tissue (astroctyes). Physical support. Glial cells have hairlike filaments which hold the neurons in place and allow the central nervous

8、 system to retain its structural integrity (astrocytes). Central Nervous System development. Glial cells provide an important function in the early and continuing development of the brain. The functions of glial cells Chemical regulation. Glial cells supply chemicals such as potassium and calcium an

9、d regulate neurotransmitter levels (astrocytes). Cleaning. Glial cells remove dead cells and other debris from the CNS (astrocytes and microglia). Isolation of the CNS. It used to be thought that glial cells were important to the Blood Brain Barrier (BBB) which shields the brain from invasion by pat

10、hogens and other unwanted cells. This function is now disputed and many neurologists now believe it is performed by the endothelial cells. Neurons are specially adapted for the transmission of electrical signalsSignal Transduction Mechanisms (I) The Nervous System Understanding Membrane Potential El

11、ectrical Excitability The Action Potential Synaptic Transmission Integration and Processing of Nerve Signals Resting membrane potential (靜止膜電位) Cells at rest normally have an excess of negative charge inside and an excess of positive charge outside the cell; the resulting electrical poteintial is ca

12、lled resting membrane potential. Negative resting membrane potential Comparing the ratio of negative to positive charge inside the cell and outside the cell, the inside of a cell typically has an excess negative charge. -60 mV for the squid giant axon（軸索） How a Cell Maintains a Membrane Potential. C

13、ations. K+ the principal intracellular cation: (potassium ion gradient) Na+ is the principal extracellular cation. Anions. Proteins, amino acids, sulfate, and phosphate are the principal intracellular anions. Cl is principal extracellular anion.Signal Transduction Mechanisms (I) The Nervous System U

14、nderstanding Membrane Potential Electrical Excitability The Action Potential Synaptic Transmission Integration and Processing of Nerve Signals Excitable cells (興奮細胞) have the ability to generate large changes in their membrane potentials. Gated ion channels (閘門離子通道) open or close in response to stim

15、uli. The subsequent diffusion of ions leads to a change in the membrane potential. Electrical Synapses. （電性突觸） Action potentials travels directly from the presynaptic to the postsynaptic cells via gap junctions.Chemical or electrical communication between cells occurs at synapses (突觸突觸) Chemical Syn

16、apses （化學性突觸）. More common than electrical synapses. Postsynaptic chemically-gated channels exist for ions such as Na+, K+, and Cl-. Depending on which gates open the postsynaptic neuron can depolarize or hyper polarize. Acetylcholine(乙醯膽鹼乙醯膽鹼). Excitatory to skeletal muscle. Inhibitory to cardiac m

17、uscle. Secreted by the CNS, PNS.Neurotransmitter Catecholamines (兒茶酚胺兒茶酚胺). Epinephrine(腎上腺素), norepinephrine(正腎上腺素) and Dopamine(多巴胺). Can have excitatory or inhibitory effects. Secreted by the CNS and PNS. Serotonin(血清張力素血清張力素). Generally inhibitory. Widespread in the brain. Affects sleep, mood, a

18、ttention, and learning Secreted by the CNS. Amino Acids Gamma aminobutyric acid (GABA) 氨基丁氨基丁酸酸. Inhibitory. Secreted by the CNS and at invertebrate neuromuscular junctions. Glycine (甘胺酸甘胺酸). Inhibitory. Secreted by the CNS. Glutamate(麥酸酐鹽麥酸酐鹽). Excitatory. Secreted by the CNS and at invertebrate ne