细胞生理5.ppt

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1、细胞生理细胞生理5vSomatic senses vSomatic senses receptors and its classification vSomatosensory conducting pathwaysSection Outline1.Somatic senses and receptors of somatic senses1.1 Somatic sensationnMechanical sensationnThermal sensationnChemical sensationnElectromagnetic sensationnCutaneous sensationvTou

2、chvPressurevWarmthvColdvPain1.1 Somatic sensationnMullers law:Each nerve fiber is activated primarily by a certain type of stimulus and each makes specific connections to structures in the central nervous system whose activity gives rise to specific sensations.1.1 Somatic sensationnMechanoreceptornT

3、hermoreceptornNociceptor1.2 Receptors of somatic sensations and its classificationMechanoreceptornA nAdaptation:when a maintained stimulus of constant strength is applied to a receptor,the frequency of the action potentials in its sensory nerve declines over time.nReceptive field:the receptive field

4、 of a sensory unit is the area from which a stimulus produces a response in that unit.MechanoreceptornWarm receptor:C nCold receptor:AThermoreceptorNociceptor1.3 Somatosensory pathwaysnConducting pathways of superficial sensationnConducting pathways of deep sensationnConducting pathways of craniofac

5、ial sensationBrown-Sequards syndrome2.Thalamus and its sensory projection systemvRelay nucleus in the thalamusvSensory projection systemSection Outline2.1 Relay nucleus in the thalamusnSpecific sensory relay nucleusnAssociated nucleusnNonspecific thalamic nuclei2.2 Sensory projection systemnSpecific

6、 projection systemnNonspecific projection systemSpecific projection systemnSpecific projection system:vCharacteristics:Project to specific discrete portions of the neocortex (point to point)vFunction:Nonspecific projection systemnNonspecific projection system:vCharacteristics:project diffusely to th

7、e whole neocortex (point to area)vFunction:Ascending reticular activating system3.Sensory analysis function of cerebral cortexnSomatic sensory area InSomatic sensory area IInProprioceptive areanVisceral sensory areanVisual sensenAuditory sense nOsphresis and taste senseSomatic sensory area ISomatic

8、sensory area II4.PainvPain sensation and pain reactionvAcute pain and chronic painvAlgogenic substances and pain receptorvAfferent fiber of pain sensation vPrimary center of pain and its regulationvVisceral pain and referred painSection Outline4.1 Pain sensation and pain reactionnPain sensation:vPai

9、n thresholdvPain tolerance thresholdnPain reaction:4.2 Acute pain and chronic painnAcute pain:physiological painnChronic pain:pathological pain4.3 Algogenic substance and receptor of painnAlgogenic substances:K+,5-HT,bradykinin,histamine,prostaglandin(PG)nReceptor of pain:free nerve endings in skin,

10、muscle,viscera4.4 Afferent fiber of pain sensationnFast pain:A myelinated nerve fiberCharacteristics:nSlow pain:C unmyelinated nerve fiber Characteristics:4.5 Primary center of pain and its regulationnPrimary center of pain:dorsal hornnGate control theory:substantia gelatinosaGate control theory4.6

11、Visceral pain and referred painnVisceral pain:pain arises from internal organs and is often due to strong contractions of visceral muscle or its forcible deformation.Referred painnDefinition:Pain in internal organs is often sensed on the surface of the body,a sensation known as referred painnAdaptat

12、ionvPhasic receptor:Touch adapts rapidly,and its receptors are called phasic receptor.vTonic receptor:Carotid sinus,the muscle spindles,and the organs from cold,pain,and lung inflation adapt very slowly and incompletely,the receptors involved are termed tonic receptors.MechanoreceptorHearing:Mechano

13、receptorsFigure 10-19:Sound transmission through the earMechanoreceptor3.Sensory analysis function of cerebral cortexTheory of referred painnConvergence theory:somatic and visceral afferents converge on the same spino-thalamic neurons.nFacilitation theory:collateral from visceral to dorsal horn neurons receiving afferents from somatic sites,increases excitability of these neurons.