细胞肌肉.ppt
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1、第五章 肌细胞的收缩 肌肉的分类及肌细胞之间的联系特征:骨骼肌:细胞之间没有紧密连接,互不联系 心肌:细胞之间有闰盘连接,为机能合胞体单一单位平滑肌:类似平滑肌多单位平滑肌:类似骨骼肌 肌肉收缩与人体功能,平滑肌,横纹肌,Albert von Szent-Gyrgyi Nagyrapolt(A.森特焦尔季,匈牙利人)发现肌肉收缩原理,获1937年诺贝尔生理学与医学奖(for his discoveries in connection with the biological combustion processes,with special reference to vitamin C and
2、the catalysis of fumaric acid“)骨骼肌占体重的40%肌肉的病种很多,研究肌肉很有临床意义,第一节 神经-骨骼肌接头处的兴奋传递 骨骼肌受运动神经支配,肌肉本身没有自律性;运动神经末梢释放乙酰胆碱(acetylcholine,Ach);乙酰胆碱的量子式释放(quantal release);神经-骨骼肌接头(简称神经-肌接头)的结构;运动神经APAch释放骨骼肌细胞AP,一、神经-肌接头处的兴奋传递是化学传递,SIR BERNARD KATZ(Great Britain),1970 Nobel Laureate in Physiology or Medicine f
3、or their discoveries concerning the humoral transmittors in the nerve terminals and the mechanism for their storage,release and inactivation,Ulf von Euler(Sweden),Julius Axelrod(USA),His research uncovered fundamental properties of synapses,the junctions across which nerve cells signal to each other
4、 and to other types of cells.By the 1950s,he was studying the biochemistry and action of acetylcholine,a signalling molecule with which synapses linking motor nerves to muscles stimulate contraction.Katz won the Nobel for his discovery that neurotransmitter release at synapses is quantal-that is,tha
5、t at any particular synapse the amount of neurotransmitter released is never less than a certain amount,and if more is always an integral number times this amount.This circumstance arises,scientists now know,because,prior to their release into the synaptic gap,transmitter molecules reside in like-si
6、zed subcellular packages known as synaptic vesicles(more at exocytosis).,Sir Bernard Katzs Work,Axelrod received his Nobel Prize for his work on the release,reuptake and storage of the neurotransmitters epinephrine and norepinephrine,also known as adrenaline and noradrenaline.Working on monoamine ox
7、idase(MAO)inhibitors in 1957,Axelrod showed that catecholamine neurotransmitters do not merely stop working after they are released into the synapse.Instead,neurotransmitters are recaptured(reuptaken)by the pre-synaptic nerve ending,and recycled for later transmissions.He theorized that epinephrine
8、is held in tissues in an inactive form and is liberated by the nervous system when needed.This research laid the groundwork for later selective serotonin reuptake inhibitors(SSRIs),such as Prozac,which block the reuptake of another neurotransmitter,serotonin.,Julius Axelrods Work,我系著名生理学家张锡钧院士-发明乙酰胆
9、碱定量测定法,Henry Hallett Dale(Great Britain),1936 Nobel Laureate in Physiology or Medicine for their discoveries relating to chemical transmission of nerve impulses,Otto Loewi(Germany),Dales contribution,During the 1940s Dale was embroiled in the scientific debate over the nature of signaling at the syn
10、apse.Dale and others believed that signaling at the synapse was chemical,while John Carew Eccles and others believed that the synapse was electrical.It was later found that most synaptic signalling is chemical,but there are some synapses that are electrical.Dale also originated the scheme used to di
11、fferentiate neurons according to what neurotransmitter they release.Thus,neurons releasing norepinephrine(a.k.a.noradrenaline)are called noradrenergic,neurons releasing GABA are GABAergic,and so on.This scheme is related to Dales principle(sometimes erroneously referred to as Dales Law).This princip
12、le states that each neuron releases only one type of neurotransmitter.Dales principle has been shown to be false;many neurons release neuropeptides in addition to amino acids or amines(Bear,et al.2001).,运动神经末梢释放Ach如何引起肌细胞的电变化?Ach运动终板的N2型ACH受体Na+、K+、少量Ca2+通道开放终板电位(endplate potential)(去极化型局部电位)终板附近肌细胞
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