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
