*Neuroanatomi DasarDr. ZainuriDepartemen Anatomi FK UII

*KOMUNIKASI INTERSELULER :Molekul sinyal

Fungsi : Sebagai ligan: akan mengubah konfigurasi protein penyusun reseptor yg diikatnya. * Asam amino * Polipeptida * Steroid * MikromolekulMisal: Hormon Sitokin - Growth factor - NeurotransmitterENDOKRIN : Sel endokrin memproduksi hormon masuk aliran darah berpengaruh pada sel-sel lain yg letaknya jauh dari sel yg memproduksinya.PARAKRIN : Beberapa macam sel dapat memproduksi molekul yg akan berpengaruh pada sel-sel yg dekat letaknya. Salah satunya : neurotransmitter signal penghubung neuron di sinapsis(signal kimia)AUTOKRIN : Suatu molekul yg dikeluarkan oleh suatu sel, namun juga berpengaruh terhadap sel itu sendiri. JUKSTAKRIN : Suatu sel memproduksi pesan yang tidak disekresikan keluar sel diekspresikan pd membran selnya. Pesan tsb. Hanya dapat diterima oleh sel tetangga sebelahnya saja.

Forms of cell signaling. (A) Hormones produced in endocrine glands are secreted into the bloodstream and can be distributed widely throughout the body. (B) Paracrine signals are released by cells into the extracellular medium in their neighborhood and act locally. (C) Neuronal signals are transmitted along axons to remote target cells. (D) Contact-dependent signaling requires cells to be in direct membrane-to-membrane contact with each other. Many of the same types of signal molecules are used in endocrine, paracrine, and neuronal signaling. The crucial differences lie in the speed and selectivity with which the signals are delivered to their targets KOMUNIKASI SEL

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Fungsi Dasar Sistem SarafSensasiMemonitor segala perubahan/event yang terjadi di lingkungannya. Perubahan tersebut kmdn disebut stimuli dan sel yang menangkap rangsangan disebut receptors.IntegrasiSecara bersamaan berfungsi sebagai processing dan intrepretasi terhadap berbagai stimuli yang sesuaiReaksiKeluarannya bersifat motorikMengaktivasi otot dan kelenjar (glands) (typically via the release of neurotransmitters (NTs))

2 cell types Neurons Functional, signal conducting cells Neuroglia Supporting cells

*Komunikasi NeuronalNeuronSebutan untuk sel saraf dan semuaprocessusnyaMost neurons have a single axon a long (up to 1m) process designed to convey info away from the cell body.Originates from a special region of the cell body called the axon hillock.Transmit APs from the soma toward the end of the axon where they cause NT release.Often branch sparsely, forming collaterals.Each collateral may split into telodendria which end in a synaptic knob, which contains synaptic vesicles membranous bags of NTs.

Badan sel (soma)Procesus/tonjolan soma (axons/dendrites)Bagian penerima input (dendrites/soma)Bagian konduksi (axon)Bagian output/sekretori (axon terminal)

Neuroglia4. OligodendrocytesProduce the myelin sheath which provides the electrical insulation for certain neurons in the CNS

Myelination in the CNSMyelination in the PNS

Interaksi antara neuron dan astrosit pada sinapsis

*SynapsisTempat dua neuron berdekatan satu denganYang lain dan terjadi fungsi komunikasi Interneuronal NeuronMampu membuat sinap dengan 1000 atau lebih neuron lain Mampu menerima sampai 10.000 atau lebih Hubungan dengan neuron lain dokingBersinap dengan otot Myoneuronal Junction

*Action PotentialsIf VM reaches threshold, Na+ channels open and Na+ influx ensues, depolarizing the cell and causing the VM to increase. This is the rising phase of an AP. Eventually, the Na+ channel will have inactivated and the K+ channels will be open. Now, K+ effluxes and repolarization occurs. This is the falling phase. K+ channels are slow to open and slow to close. This causes the VM to take a brief dip below resting VM. This dip is the undershoot and is an example of hyperpolarization.

*Animasi

*Na+ ChannelsThey have 2 gates.At rest, one is closed (the activation gate) and the other is open (the inactivation gate).Suprathreshold depolarization affects both of them.12Animasi

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*Saltatory ConductionOccurs in myelinated axons.Saltare is a Latin word meaning to leap.Recall that the myelin sheath is not completed. There exist myelin free regions along the axon, the nodes of Ranvier.

*Animasi

*Synaptic TransmissionAn AP reaches the axon terminal of the presynaptic cell and causes V-gated Ca2+ channels to open.Ca2+ rushes in, binds to regulatory proteins & initiates NT exocytosis.NTs diffuse across the synaptic cleft and then bind to receptors on the postsynaptic membrane and initiate some sort of response on the postsynaptic cell.

Axon teraktivasi dan tidak teraktivasi

*Conversion of chemical signal to electrical signalNeurotransmitter diffuses across synaptic cleft and binds to neurotransmitter receptors concentrated on postsynaptic membrane of target cellBinding of neurotransmitter to receptors change in membrane potentialIf membrane potential depolarises above threshold action potentialNeurotransmitter rapidly removed from synaptic cleft by enzyme degradation or reuptake into terminal when presynaptic cell stops firing postsynaptic cells stop firingNeurotransmitter receptors of various types but most commonly transmitter (ligand)-gated ion channels rapid response - milliseconds

*Excitatory and inhibitory synapsesExcitatory neurotransmitters cause postsynaptic cell to fire action potentialsInhibitory neurotransmitters prevent postsynaptic cell from firingExcitatory neurotransmitters (eg acetylcholine, glutamine) act on ion channel receptors selective for Na+ and Ca2+Neurotransmitter binding to receptor channel opening Na+ influx depolarisation of postsynaptic membrane threshold action potentialInhibitory neurotransmitters (eg -aminobutyric acid (GABA) and glycine) act on Cl- channelsNeurotransmitter binding to receptor channel opening Cl- influx prevents depolarisation of postsynaptic membrane no action potential

*EPSPs & IPSPsTypically, a single synaptic interaction will not create a graded depolarization strong enough to migrate to the axon hillock and induce the firing of an AP.However, a graded depolarization will bring the neuronal VM closer to threshold. Thus, its often referred to as an excitatory postsynaptic potential or EPSP.Graded hyperpolarizations bring the neuronal VM farther away from threshold and thus are referred to as inhibitory postsynaptic potentials or IPSPs.

Pembagian secara anatomis

Organisasi sistem saraf2 pembagian utama:Sistem saraf pusatOtak + Medula spinalisMrpk pusat kontrol dan integrasiSistem saraf periferSistem saraf yang keluar dari otak dan med. spinalisTerdiri dari:31 pasang saraf SpinalMembawa sinyal ke dan dari med. spinalis12 pasang saraf CranialMembawa sinyal ke dan dari otak

*Lobus pada cortex cerebri: Frontalis, Parietalis, Temporalis, Occipitalis, Limbik, Insularis.

CORTEX CEREBRI

Thalamus80% of the diencephalon Sensory relay station where sensory signals can be edited, sorted, and routed.Also has profound input on motor (via the basal ganglia and cerebellum) and cognitive function.Not all functions have been elucidated.

HypothalamusFungsi:Pusat kontrol autonomInfluences HR, BP, resp. rate, GI motility, pupillary diameter.Can you hold your breath until you die?Respon Emotional Involved in fear, loathing, pleasureDrive center: sex, hungerPengatur Suhu TubuhPengatur Masukan makananContains a satiety centerPengaturan keseimbangan cairan dan hausPengaturan siklus tidur/jagaPengontrol hormonReleases hormones that influence hormonal secretion from the anterior pituitary gland.Releases oxytocin and vasopressin

Limbic SystemIncludes nuclei and tracts along the border btwn the cerebrum and the diencephalon.Functional grouping rather than anatomicalFunctions include:Establishing emotional statesLinking conscious cerebral cortical functions w/ unconscious functions of the brainstemFacilitating memory storage and retrievalLimbic lobe of the cerebrum consists of 3 gyri that curve along the corpus callosum and medial surface of the temporal lobe.Limbic system the center of emotion anger, fear, sexual arousal, pleasure, and sadness.

CerebellumLies inferior to the cerebrum and occupies the posterior cranial fossa.

2nd largest region of the brain.10% of the brain by volume, but it contains 50% of its neuronsHas 2 primary functions:Adjusting the postural muscles of the bodyCoordinates rapid, automatic adjustments, that maintain balance and equilibriumProgramming and fine-tuning movements controlled at the subconscious and conscious levelsRefines learned movement patterns by regulating activity of both the pyramidal and extrapyarmidal motor pathways of the cerebral cortexCompares motor commands with sensory info from muscles and joints and performs any adjustments to make the movement smooth

CerebellumThe cerebellum can be permanently damaged by trauma or stroke or temporarily affected by drugs such as alcohol.These alterations can produce ataxia a disturbance in balance.

Pembagian secara embriologis

Sistem Saraf PeriferMenghubungkan timbal balik antara sistem saraf pusat dengan bagian-bagian tubuh.Dapat dibagi menjadi:Divisi Sensoris Afferent Menghantarkan sinyal dari reseptor ke SS pusatInformasi berasal dari bagian dalam tubuh dan dari luar Serabut saraf sensoris terdiri dari somatic (dari kulit, otot rangka atau sendi) atau visceral (organ2 organ dalam)Divisi MotorEfferent Menghantarkan sinyal/impuls dari SS pusat ke organ target/effector (muscles/glands)Serabut saraf terdiri dari Somatomotorik bersifat VOLUNTARY (volunter/disadari) menuju ke otot rangka atau visceromotorik bersifat INVOLUNTARY (involunter/tak disadari) meniji ke otot polos, otot jantung dan kelenjar

Peripheral nervous system

Pembagian secara fungsional

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