Jaringan Saraf

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Text of Jaringan Saraf

NEURAL TISSUENEURAL TISSUEOVERVIEW SISTEM SARAFOVERVIEW SISTEM SARAFSistem Saraf : 3 % berat badan tubuhUnit fungsional dasar : NEURONJaringan saraf menyusun organ-organ sistem saraf : otak, medulla spinalis, reseptor di organ spesifkDibagi 2 : CNS (Central Nervous System) dan PNS (Peripheral Nervous System)CNS : otak dan medulla spinalisPNS : seluruh jaringan saraf diluar CNSNEURONNEURONBadan sel / somaDendrit Akson Sinaps: Pre sinaptic cell and Post synaptic cellNEURONNEURONKLASIFIKASI STRUKTURAL NEURONKLASIFIKASI STRUKTURAL NEURONNeuron Anaksonik Neuron bipolarNeuron unipolarNeuron multipolarKLASIFIKASI FUNGSIONAL NEURONKLASIFIKASI FUNGSIONAL NEURONNeuron Sensorik/aferenNeuron Motorik/eferenInterneuronNEURON SENSORIK (SENSORY NEURON SENSORIK (SENSORY NEURONS)NEURONS)mengirimkan informasi dari reseptor sensorik ke CNSbadan selnya terletak di ganglion sensorik perifermengumpulkan informasi dari luar (somatic sensory neuron) dan dalam (visceral sensory neuron)Reseptor : - ekteroseptor : sentuhan, panas, bau, suara- propioseptor : pergerakan otot dan sendi- interoseptor : organ visceral, nyeri, deep pressureNEURON MOTORIK (MOTOR NEURON MOTORIK (MOTOR NEURONS)NEURONS)membawa informasi dari CNS ke periferbadan sel terletak di CNSTerdiri dari : SNS (Somatic Nervous System) dan ANS (Autonomic Nervous System)Neuron motorik somatis : inervasi otot skelet, badan selnya di CNS, aksonnya memanjang sampai ke neuromuscular junctionNeuron motorik visceral (autonom) : inervasi selain otot skeletNEUROGLIANEUROGLIACNSEpendymal cellsAstrocytesOligodendrocytesMicroglia PNSSel satelitSel schwansNEUROFISIOLOGINEUROFISIOLOGIAktivitas neuron dimulai akibat adanya perubahan potensial istirahatStimulus menimbulkan perubahan potensial transmembran (graded potentials)Stimulus potensial aksi di membran aksonPOTENSIAL TRANSMEMBRANPOTENSIAL TRANSMEMBRANKomposisi ion di ICF (tinggi K+) dan ECF (tinggi Na+)Membran sel bersifat semipermeabelTransport aktif dan pasifTRANSPORT PASIFTRANSPORT PASIFChemical gradients : perpindahan K+ ke ECF, Na+ ke ICF, karena perbedaan konsentrasiElectrical gradientsMembran sel lebih permeabel terhadap ion K+ dibanding Na+, akibatnya tingkat ke-positif-an ICF cenderung lebih rendah dibanding ECF ( perbedaan potensial)Electrochemical gradientsmembentuk energi potensialTRANSPORT AKTIFTRANSPORT AKTIFPerpindahan Na+ : K+ = 3 : 2Membutuhkan energi dari ATPPompa Na+ K+PERUBAHAN POTENSIAL PERUBAHAN POTENSIAL TRANSMEMBRANTRANSMEMBRANMembran channel mengontrol pergerakan ion melewati membranPassive channels / leak channels : selalu terbuka, berperan menjaga kestabilan saat potensial istirahatActive/gate channels : membuka/menutup tergantung stimulus- Chemically regulated channels - Voltage-regulated channels - Mechanically regulated channels CHEMICALLY REGULATED CHEMICALLY REGULATED CHANNELSCHANNELSVOLTAGE-REGULATED CHANNELSVOLTAGE-REGULATED CHANNELSMECHANICALLY REGULATED MECHANICALLY REGULATED CHANNELSCHANNELSGRADED POTENTIALSGRADED POTENTIALSLocal potentialsStimulus channel terbuka graded potentialsDepolarisasi : perubahan/penurunan potensial transmembran, Na masuk ke ICFDerajat depolarisasi dipengaruhi oleh stimulus, sitosol, leak channelsHiperpolarisasi : penurunan potensial transmembran, menjadi semakin negatif, K+ keluar ke ECFRepolarisasi : kembali ke potensial istirahatPOTENSIAL AKSIPOTENSIAL AKSIStimulus mampu membuka voltage-regulated sodium channels (10-15mV)Timbulnya potensial aksi :- depolarisasi- aktivasi sodium channels (positive feed back)- inaktivasi sodium channels dan aktivasi potassium channels-kembali ke normalPeriode refraktori : periode sejak timbulnya potensial aksi sam pai kembali ke potensial istirahat., dimana membran tidak berespon terhadap stimulus tambahanKLASIFIKASI AKSONKLASIFIKASI AKSONType A fbers are the largest axons, with diameters ranging from 4 to 20 m. These are myelinated axons that carry action potentials at speeds of up to 140 meters per second, or over 300 mph. Type B fbers are smaller myelinated axons, with diameters of 2-4 m. Their propagation speeds average around 18 meters per second, or roughly 40 mph. Type C fbers are unmyelinated and less than 2 m in diameter. These axons propagate action potentials at the leisurely pace of 1 meter per second, or a mere 2 mphType A fbers carry to the CNS sensory information about position, balance, and delicate touch and pressure sensations from the skin surface. The motor neurons that control skeletal muscles also send their commands over large, myelinated Type A axons. Type B fbers and Type C fbers carry to the CNS information about temperature, pain, and general touch and pressure sensations and carry instructions to smooth muscle, cardiac muscle, glands, and other peripheral efectors.SINAPSSINAPSPada sistem saraf, informasi dikonduksikan di sepanjang akson dalam bentuk potensial aksi (impuls saraf)Perjalanan impuls antar neuron diperantarai oleh sinapsPresinaptic neuronPostsinaptic neuronELECTRICAL SINAPSELECTRICAL SINAPSCNS dan PNS, jarangThey are present in some areas of the brain, including the vestibular nuclei, in the eye, and in at least one pair of PNS ganglia (the ciliary ganglia). At an electrical synapse, the presynaptic and postsynaptic membranes are locked together at gap junctions. The lipid portions of the opposing membranes, separated by only 2 nm, are held in position by binding between integral membrane proteins called connexons. These proteins contain pores that permit the passage of ions between the cells. Because the two cells are linked in this way, changes in the transmembrane potential of one cell will produce local currents that afect the other cell as if the two shared a common cell membrane. As a result, an electrical synapse quickly and efciently propagates action potentials from one cell to the next.CHEMICAL SINAPSCHEMICAL SINAPSPeran neurotransmitterEksitasi dan inhibisiAsetilkolin (Ach)- terdapat di semua neuromuscular junction otot skelet- banyak di CNS- seluruh neuron PNS- seluruh neuromuscular dan neuroglandular parasimpatik ANSPEMROSESAN INFORMASIPEMROSESAN INFORMASINEUROTRANSMITTER LAINNEUROTRANSMITTER LAINNorepinephrineDopamineSerotoniinGamma aminobutyric acid/GABANeuromodulator: komponen yang mempengaruhi sekresi neurotransmitterNEUROTRANSMITTER DAN NEUROTRANSMITTER DAN NEUROMODULATORNEUROMODULATORMemiliki efek langsung terhadap potensial membran dengan membuka.menutup channelsMemiliki efektidak langsung terhadap potensial membran, sehingga memerlukan second messengerLipid solubelLife is beautifulAlways pray