參考案例100期生化nervous

1、Part 3Sensory Function of the Nervous SystemI Sensory pathwaysSensory systems allow us to detect, analyze and respond to environmentCarry information from sensory receptors to the brainSpecial sensation: reach cerebral cortexNo Sensation : do not reach cerebral cortexSensation 1.somatic sensation： s

2、uperficial sensation：from skin touch, pressure, pain, temperature deepsensation： proprioception from muscle, tendon, joint, etc position sensation motion sensation 2.visceral sensation ： pain1. Sensory receptorsA: Free nerve endings (pain, temperature)B: Pacinian corpuscle (pressure)C: Meissners cor

3、puscle (touch)D: Muscle spindle (stretch)ABCD 2. Sensory pathways:1st: dorsal root ganglia, cerebral ganglia 2nd: dorsal horn, nucleus gracilis, nucleus cuneatus, cranial nerve nuclei 3rd: Thalamus sensory relay nuclei （1）deepsensation pathwayDorsal column- Medial lemniscusProprioceptionFine touch -

4、 pressure ： two-point discrimination surfacecharacteristicPrimary somatosensory cortex (S1) in parietal lobeThalamus (VP nucleus)MedullaMediallemniscusSpinal cordDorsal columnDorsal columnnucleidorsal cloumnpathwaydeepsensation pathway先上行,后交叉Dorsal column damagedorsal column pathwayspinal cord injur

5、yLoss of sense of:touchproprioceptionvibrationin left legPain, temperature, Rough touch pressure (2) superficial sensation pathwaySpinothalamic Pathway pro-Lateral funiculusPrimary somatosensory cortex (S1)Thalamus (Intralaminar and VP nuclei)MedullaSpinal dorsal cordSpinothalamic tractspinothalamic

6、pathwaysuperficial sensation pathway先交叉后上行Spinothalamic damagespinothalamic pathwayLHSspinal cord injuryLoss of sense of:TouchPainWarmth/coldin right legCentral Pathways3.Sensory function of thalamusThalamic sensory nucleus 1) Specific sensory relay nucleus Receive the 2nd sensory afferent fibers an

7、d project to the specific area of cerebral cortex.Function: makes the special sense. 后腹核，內(nèi)、外側(cè)膝狀體（黃色）2) Associated nucleus receive fibers from thalamus sensory relay nucleus and other subcortical central, and project to the specific area of the cortex. Function: Coordinate between thalamus and cerebr

8、alcortex 丘腦前核、丘腦外側(cè)腹核、丘腦枕核等（紅色）3) Nonspecific projection nucleus Receive fibers from the ascending reticular system and project to all areas of the cortex by multi-synapase. Function: maintain and change the states of consciousness. 中央中核、束旁核、中央外側(cè)核(藍(lán)色)(2) Sensory projection system 1) specific projecti

9、on system Specific sensory relay nucleus, associated nucleus and the projecting to the special area of the cerebral cortex are called specific projection system. It is point to point to the special area of the cortex. Function: Make the special sense. Stimulate efferent impulses from the cortex.2) n

10、onspecific projection system Nonspecific projection nucleus and the projecting to widespread areas of cortex. Diffuse projections, Non-point to point to the cortex. The common pathways of different sense. Function:maintain and change consciousness of cortex.腦干網(wǎng)狀結(jié)構(gòu)實(shí)線：特異投射系統(tǒng)；虛線：非特異投射系統(tǒng)ascending reticu

11、lar activating system 腦干網(wǎng)狀結(jié)構(gòu)上行激動(dòng)系統(tǒng)The differences between specific and nonspecific projection systemspecific projection systemnonspecific projection systemrespond to a certain stimulusrespond to various stimuliA few synapses onlymulti-synapses point to point to the cortexdiffuse projection to the co

12、rtexspecial sensemaintain of consciousness4. Sensory function of cerebral cortex: molecular layer: external granular layer: layer of small pyramidal cells: internal granular layer: large pyramid cell layer: layer of polymorphic cells(1) Structural characteristics of the cerebral cortexSensory column

13、 The neurons of the somatosensory cortex arearranged in vertical columns extending all the waythrough the six layers of the cortex, each of these columns serves a single specific sensory modality. 半球外側(cè)面 半球內(nèi)側(cè)面Brodmanns area : 52 area 1) somatosensory area, S postcentral gyrus of the cerebral cortex.

14、( in Broadmanns areas 3,1, and 2)(2) Somatic sensory area中央后回Sensation Projection characteristicCrossed projection The cortex receives sensory information from the opposite side of the body ( Exception: sensory information from the face is projected to both side of cortex).Inverted human ( Exception

15、: the face is up-right. ) The projection areas are directly proportional to distinguish of sense.Sensation Projection characteristic2) somatosensory area ,S Located between postcentral gyrus and insula (腦島) Bilateral project, up-right.3) Proprioceptive area Located in the precentral gyrus ( in Brodm

16、anns area 4).4) vision area calcarine sulcus characteristic: nasalside crossde bitamporal side uncrossed (鼻側(cè)交叉，顳側(cè)不交叉）(膝狀體距狀束)左右5) auditory areasuperior temporal gyrus,transversegyruscharacteristic: bilateral, but mainly fromopposite side（3）visceral area mixed in S ; S II, supplementary motor area, l

17、imbic system II . Pain“Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage”1. NociceptorsNociceptors are free nerve endings in skin that respond only to noxious stimuli and generate nerve impulses which the bra

18、in interprets as pain. algogenic substance : K+, H+, 5-HT, PG and substance P, Bradykinin, histamine, etc No Adequate StimulationFast pain (acute)occured rapidly after stimuli (0.1 second) Disappeared rapidlysharp pain, pricking pain like needle puncture or cutClearly localizedlarger A nerve fibers

19、(30 m/s) not felt in deeper tissues2. Fast Pain and Slow PainSlow pain (chronic)begins more slowly & increases in intensity Disappeared slowlyin both superficial and deeper tissues，burning painPoorly localized Often panied by unpleasant emotionssmaller C nerve fibers (0.4 m/s)3. Somatic Pain and Vis

20、ceral Pain Somatic Pain Superficial Pain: from skin areas, Fast Pain to Slow Pain Deep Pain: from muscle, joints, tendons & fascia Slow Pain Visceral Pain arises from receptors in visceral organsCharacteristic of visceral pain:1) Poorly localized, maybe 2) begins more slowly, continue and increases in intensity3) Sensitive to inflammation, ischemia, spasm, stretch, but insensitive to cutting and burning.4) pany