组胚学英文版Nervous-Tissue.ppt

,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Nervous Tissue,.General Characteristics,A.Made up of,2 types of cells,:,neurons,-structural and functional unit;,neuroglia,-supporting,protecting and nourishing neurons.,B.,Neurons,Unique,processes,;,Forming,synapses,;,Conducting,impulses.,C.Making up,nervous system,:,CNS,-brain and spinal cord;,PNS,-ganglia,nerves.,D.Function:integrating and coordinating body activities.,A.Cell body,:metabolic,tropic and integral center,1.,Nucleus,large,spherical,and,pale-staining,;,a,prominent nucleolus,.,a.,Nissl bodies,Basophilic,particles,RER,+,free ribosomes,Indicating,active protein synthesis,.,2.,Perikaryon,-perinuclear cytoplasm,Containing,Nissl bodies,;,Receiving information and conducting it to parent cell body.,2.Axon,One,axon each neuron;,Long,and,thin,does not branch profusely;,C.Classification,1.According to,number of processes,Pseudounipolar,:found in spinal ganglia;,Bipolar,:present in cochlear and vestibular ganglia,retina,olfactory,etc;,Multipolor,:majority of neurons.,2.According to,function,Sensory,or,afferent,;,Motor,or,efferent,;,Interneurons,:account for,99%,of neurons in the body.,3.According to,neurotransmitter,released,Cholinergic,:acetylcholine(,Ach,);,Aminergic,:norepinephrine(NE),DA,5-HT;,Peptidergic,:polypeptides such as substance P,vasopressin,etc.,III,.Synapses,A.Definition:,Junction,between two,neurons,or,between,a neuron and an effecter cell,specialized for,transmission,of impulses.,Ultra structure model of synapses,C.Structure of chemical synapses,Synaptic boutons,Presynaptic element,Synaptic cleft,Postsynaptic element,1.,Presynaptic element(terminal),Usually,axon terminal,;,Synaptic vesicles,Mit,SER;,Clear vesicles Ach;dense core vesicles Amines,peptides,Dense projections,2.,Synaptic cleft,Extracellular space between pre-and postsynaptic membranes.,3.Postsynaptic element,Usually dendrite(or spine)or cell body;,Postsynaptic membrane thickened,(,type I,type II,);,Receptors,to the neurotransmitter.,.Neuroglia,A.General features,1.,More,than neurons by 5-10 times;,2.With processes,but,not,conduct impulses,;,3.Only nuclei seen with Nissl stains.Silver staining shows processes and cytoplasm;,4.Can,divide after birth,;,B.Neuroglia in CNS,1.Astrocytes,Most numerous;oval,pale staining nucleus,;,Many processes,:fibrous and protoplasmic;,Glial filaments(,GFAP,);,Support&separate neurons,repair,secrete NTF,etc;,Component of,blood-brain barrier,endothelial cells with tight junctions;,continuous basal lamina;,vascular feet of astrocyte processes.,2.,Oligodendrocytes,Smaller with a round,dark-staining nucleus;,Forming,myelin sheath,around axons in the CNS.,3.Microglia,smallest with a irregular,darkly stained nucleus;,Phagocytic,;,Derived from monocytes.,4.Ependymal cells,columnar or cuboidal epithelioid cells;,lining ventricles of brain and central canal of spinal cord.,C.Neuroglia in PNS,1.Schwann cells,Forming,myelin sheath,around axons in PNS;,Secreting neurotrophic factors(NGF,BDNF).,2.,Capsular cells,(satellite cells),A layer of flattened or cuboidal cells;,Forming capsule around neurons in peripheral ganglia.,.Nerve Fibers,A.Myelinated nerve fibers in PNS,1.Basic structure,Axon,+,myelin sheath,+,neurolemma,;,Node of Ranvier,Portions devoid of myelin sheath;,Internode,between 2 consecutive nodes-one Schwann cell.,2.Myelin sheath,a.LM:,sponge like(H&E),Black(OsO,4,).,b.EM:,concentric lamellae.,c.,Incisures of Schmidt-Lanterman:,cone-shaped clefts(contain cytoplasm).,d.Formation,Schwann cell,plasmalemma winding,around axon many times.,Ranvier node,3.Neurolemma,Outermost layer of,cytoplasm,cell membrane and basai lamina,of Schwann cells.,B.Myelinated nerve fibers in CNS,Similar to Myelinated nerve fibers in PNS;,No neurolemma,no incisures of Schmidt-Lanterman,;,Myelin sheath,is formed by processes of,oligodendrocytes,.,C.Unmyelinated nerve fibers,1.PNS,No myelin sheath and nodes of Ranvier,.,Thin axons(single or group)indented into Schwann cells;,2.CNS,Free axons,among other neuronal and glial processes,Unmyelinated nerve fiber),D.Functional role,1.Unmyelinated nerve fibers,continuous conduction,Enhancing conduction speed,via,saltatory conduction,;,Thicker axon thicker myelin sheath and longer internode greater conduction velocity.,2.Myelinated nerve fibers,:,A.Nerves,-,Made up of,nerve fibers,and,connective tissue,.Nerve and nerve endings,1.Nerve fibers,Mixed,-both myelin Ted and unmyelinated,sensory and motor.,Epineurium:,Fibrous Ct enclosing entire nerve;,Perineurium:,Sheet of flattened epithelium-like cells surrounding each nerve bundles;,Endoneurium:,Thin layer of LCt enveloping each nerve fiber.,Ep,Pe,2.Connective tissue,Ep,Alzheimer disease,is the most common form of dementia in the elderly(60%80%of cases).It is characterized by extracellular deposition of Ab protein(plaques),intracellular neuro brillary tangles(inset:N,normal neuron;T,neuron cell body lled with dark-staining tangles),and loss of neurons and synapses in the cerebral cortex and some subcortical regions.,1.Classification,(1)Sensory(receptors),(2)Motor(effectors),B.Nerve endings,a.,Free nerve endings,b.Encapsulated nerve endings,Tactile corpuscles,Lamellated corpuscles,Muscular spindles,a.Somatic(,motor end plate,),b.Visceral,2.Free nerve endings,Abundant in,epidermis,cornea,hair follicles;,Branches of,naked nerve fibers;,Responding to,cold,heat and pain.,3.Tactile(Meissner)corpuscles,Found in,dermal papillae;,Touch,receptors;,Oval bodies with,flattened cells,CT capsule,and,nerve terminal(s),.,4.Lamellated(Pacinian)corpuscles,Distributed in,subcutaneous tissue,mesentery,;,Perceiving,pressue,and,vibration,;,Composed of,concentric lamellae,of,flattened cells,an,internal cylinder,and,naked nerve fiber terminal(s).,5.Muscular spindles,Distributed in,skeletal muscle,;,Formed by CT capsule,intrafusal muscle fibers,(thin,striated,nuclei arranged in chain or cluster);,Nerve fibers,end as annulospiral or flower-spray endings;,Proprioceptors,:detecting muscle length and its changes to,regulate muscle tone,.,6.Motor end plate(myoneural junction),Synapse,between,motor nerve terminals,and,skeletal muscle fibers,causing muscle,contraction,;,LM:Nerve fibers ramify with each terminal dilating as a,plate like mass,touching a muscle fiber;,motor nerve ending,myoneural junction,Motor end plate,EM:,Presynaptic element(axon terminal)vesicles containing,Ach,postsynaptic membrane(sarcolemma),N receptors,for Ach.,NERVOUS TISSUE REVIEW,The cell types that make up nervous tissue,General structure features,classification,distribution and function of neurons,The ultrastructure and functional mechanism of chemical synapse,Structural features,classification and function of neoroglial cells,Classification and organization of nerve fibers and nerves,