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Neuroanatomi DasarNeuroanatomi Dasar

Dr. ZainuriDr. ZainuriDepartemen Anatomi FK UIIDepartemen Anatomi FK UII

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KOMUNIKASI INTERSELULER :KOMUNIKASI INTERSELULER :Molekul sinyal

Fungsi : Sebagai ligan: akan mengubah konfigurasi protein penyusun reseptor yg diikatnya.

* Asam amino * Asam amino * * Polipeptida Polipeptida * * Steroid Steroid * * MikromolekulMikromolekul

Misal: Misal: - Hormon Hormon - Sitokin Sitokin - Growth factor - Growth factor - - Neurotransmitter

ENDOKRIN : : Sel endokrin Sel endokrin memproduksi memproduksi hormon → masuk hormon → masuk aliran darah → aliran darah → berpengaruh pada berpengaruh pada sel-sel lain yg sel-sel lain yg letaknya jauh dari letaknya jauh dari sel yg sel yg memproduksinya.memproduksinya.

PARAKRIN : : Beberapa macam Beberapa macam sel dapat sel dapat memproduksi memproduksi molekul yg akan molekul yg akan berpengaruh pada berpengaruh pada sel-sel yg dekat sel-sel yg dekat letaknya.letaknya. Salah satunya :Salah satunya : neurotransmitter signal penghubung signal penghubung neuron di sinapsisneuron di sinapsis(signal kimia)(signal kimia)

AUTOKRIN : : Suatu molekul yg Suatu molekul yg dikeluarkan oleh dikeluarkan oleh suatu sel, namun suatu sel, namun juga berpengaruh juga berpengaruh terhadap sel itu terhadap sel itu sendiri.sendiri.

JUKSTAKRINJUKSTAKRIN : : Suatu sel Suatu sel memproduksi pesan memproduksi pesan yang tidak yang tidak disekresikan keluar disekresikan keluar sel diekspresikan pd sel diekspresikan pd membran selnya. membran selnya. Pesan tsb. Hanya Pesan tsb. Hanya dapat diterima oleh dapat diterima oleh sel tetangga sel tetangga sebelahnya saja.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 SarafFungsi Dasar Sistem Saraf

1.1. SensasiSensasi Memonitor segala perubahan/event yang terjadi di Memonitor segala perubahan/event yang terjadi di

lingkungannya. Perubahan tersebut kmdn disebut lingkungannya. Perubahan tersebut kmdn disebut stimulistimuli dan sel dan sel yang menangkap rangsangan disebut yang menangkap rangsangan disebut receptorsreceptors..

2.2. IntegrasiIntegrasi Secara bersamaan berfungsi sebagai processing dan intrepretasi Secara bersamaan berfungsi sebagai processing dan intrepretasi

terhadap berbagai stimuli yang sesuaiterhadap berbagai stimuli yang sesuai

3.3. ReaksiReaksi Keluarannya bersifat motorikKeluarannya bersifat motorik

Mengaktivasi otot dan kelenjar (glands) (typically via the release of Mengaktivasi otot dan kelenjar (glands) (typically via the release of neurotransmittersneurotransmitters (NTs)) (NTs))2 cell types

1. Neurons Functional, signal conducting cells

2. Neuroglia Supporting cells

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Komunikasi NeuronalKomunikasi NeuronalNeuron Sebutan untuk sel saraf dan semua

processusnya

Most neurons have a single Most neurons have a single axonaxon – a long – a long (up to 1m) process designed to convey info (up to 1m) process designed to convey info away from the cell body.away from the cell body.

Originates from a special region of the cell Originates from a special region of the cell body called the body called the axon hillockaxon hillock..

Transmit APs from the soma toward the end Transmit APs from the soma toward the end of the axon where they cause NT release.of the axon where they cause NT release.

Often branch sparsely, forming Often branch sparsely, forming collateralscollaterals.. Each collateral may split into Each collateral may split into telodendriatelodendria

which end in a which end in a synaptic knobsynaptic knob, which , which contains contains synaptic vesiclessynaptic vesicles – membranous – membranous bags of NTs.bags of NTs. - Badan sel (soma)

- Procesus/tonjolan soma (axons/dendrites)

- Bagian penerima input (dendrites/soma)

- Bagian konduksi (axon)- Bagian output/sekretori

(axon terminal)

NeurogliaNeuroglia

4. Oligodendrocytes4. Oligodendrocytes Produce the Produce the

myelin myelin sheathsheath which which provides the provides the electrical electrical insulation for insulation for certain certain neurons in the neurons in the CNSCNS

Myelination in the CNS

Myelination in the PNS

Substantia grisea

Substantia alba

Interaksi antara neuron dan astrosit pada sinapsis

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SynapsisSynapsisTempat dua neuron berdekatan satu denganYang lain dan terjadi fungsi komunikasi Interneuronal

Neuron

Mampu membuat sinap dengan 1000 atau lebih neuron lain

Mampu menerima sampai 10.000 atau lebih Hubungan dengan neuron lain

doking

Bersinap dengan otot

Myoneuronal Junction

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Action PotentialsAction Potentials If VIf VMM reaches threshold, Na reaches threshold, Na+ + channels open and Nachannels open and Na++ influx influx

ensues, depolarizing the cell and causing the Vensues, depolarizing the cell and causing the VMM to increase. to increase. This is the rising phase of an AP. This is the rising phase of an AP.

Eventually, the NaEventually, the Na++ channel will have inactivated and the K channel will have inactivated and the K++ channels will be open. Now, Kchannels will be open. Now, K++ effluxes and repolarization effluxes and repolarization occurs. This is the falling phase. occurs. This is the falling phase. KK++ channels are slow to open and slow to close. This causes the V channels are slow to open and slow to close. This causes the VMM to to

take a brief dip below resting Vtake a brief dip below resting VMM. This dip is the . This dip is the undershootundershoot and is an and is an example of example of hyperpolarizationhyperpolarization..

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Animasi

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NaNa++ Channels Channels They have 2 gates.They have 2 gates.

At rest, one is closed (the At rest, one is closed (the activationactivation gategate) and the ) and the other is open (the other is open (the inactivationinactivation gategate).).

Suprathreshold Suprathreshold depolarization affects both depolarization affects both of them.of them.

1

2

Animasi

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3

4 5

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Saltatory ConductionSaltatory Conduction Occurs in myelinated axons.Occurs in myelinated axons. SaltareSaltare is a Latin word meaning “to leap.” is a Latin word meaning “to leap.” Recall that the myelin sheath is not completed. There exist Recall that the myelin sheath is not completed. There exist

myelin free regions along the axon, the nodes of Ranvier.myelin free regions along the axon, the nodes of Ranvier.

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Animasi

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Synaptic Synaptic TransmissionTransmission An AP reaches the axon An AP reaches the axon

terminal of the presynaptic terminal of the presynaptic cell and causes V-gated cell and causes V-gated CaCa2+2+ channels to open. channels to open.

CaCa2+2+ rushes in, binds to rushes in, binds to regulatory proteins & regulatory proteins & initiates NT exocytosis.initiates NT exocytosis.

NTs diffuse across the NTs diffuse across the synaptic cleft and then synaptic cleft and then bind to receptors on the bind to receptors on the postsynaptic membrane postsynaptic membrane and initiate some sort of and initiate some sort of response on the response on the postsynaptic cell.postsynaptic cell.

Axon teraktivasi dan tidak teraktivasiAxon terminal sebelum teraktivasi

Axon terminal teraktivasi

Voltage gatedCa2+ tertutup

Presinaptik(axon terminal)

NeurotransmiterVesikel sinaptik

Celah sinaptik Reseptor neurotransmiter

Sel postsinaptik

Voltage gatedCa2+ terbuka

Neurotransmiterdilepas ke celah sinaptik

Impuls saraf(signal elektrik/potensial aksi)

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Conversion of chemical signal to electrical signal

Neurotransmitter diffuses across synaptic cleft and binds to neurotransmitter receptors concentrated on postsynaptic membrane of target cell

Binding of neurotransmitter to receptors change in membrane potential

If membrane potential depolarises above threshold action potential

Neurotransmitter rapidly removed from synaptic cleft by enzyme degradation or reuptake into terminal when presynaptic cell stops firing postsynaptic cells stop firing

Neurotransmitter receptors of various types but most commonly transmitter (ligand)-gated ion channels rapid response - milliseconds

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Excitatory and inhibitory synapses Excitatory neurotransmitters cause postsynaptic cell to fire

action potentials Inhibitory neurotransmitters prevent postsynaptic cell from

firing Excitatory 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 potential

Inhibitory neurotransmitters (eg -aminobutyric acid (GABA) and glycine) act on Cl- channels

Neurotransmitter binding to receptor channel opening Cl- influx prevents depolarisation of postsynaptic membrane no action potential

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EPSPs & IPSPsEPSPs & IPSPs Typically, a single synaptic interaction will Typically, a single synaptic interaction will

not create a graded depolarization not create a graded depolarization strong enough to migrate strong enough to migrate to the axon hillock and to the axon hillock and induce the firing of an AP. induce the firing of an AP. However, a graded depolarization will bring the neuronal VHowever, a graded depolarization will bring the neuronal VMM closer to closer to

threshold. Thus, it’s often referred to as an threshold. Thus, it’s often referred to as an excitatory postsynaptic excitatory postsynaptic potential or EPSPpotential or EPSP..

Graded hyperpolarizations bring the Graded hyperpolarizations bring the neuronal Vneuronal VMM farther away from threshold farther away from threshold and thus are referred to as and thus are referred to as inhibitory postsynaptic inhibitory postsynaptic potentials or IPSPs. potentials or IPSPs.

Pembagian secara anatomis

Organisasi sistem sarafOrganisasi sistem saraf

2 pembagian utama:2 pembagian utama:1.1. Sistem saraf pusatSistem saraf pusat

Otak + Medula spinalisOtak + Medula spinalis Mrpk pusat kontrol dan Mrpk pusat kontrol dan

integrasiintegrasi

2.2. Sistem saraf periferSistem saraf perifer Sistem saraf yang keluar dari Sistem saraf yang keluar dari

otak dan med. spinalisotak dan med. spinalis Terdiri dari:Terdiri dari:

31 pasang saraf Spinal31 pasang saraf Spinal Membawa sinyal ke Membawa sinyal ke

dan dari med. spinalisdan dari med. spinalis 12 pasang saraf Cranial12 pasang saraf Cranial

Membawa sinyal ke Membawa sinyal ke dan dari otakdan dari otak

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SulcusGyrus

Fissura

Lobus

Cerebrum

Cerebelum

Medulla oblongataMesencephalon

Substantia grisea

Substantia alba

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

CORTEX CEREBRI

ThalamusThalamus 80% of the diencephalon 80% of the diencephalon Sensory relay station where sensory Sensory relay station where sensory

signals can be edited, sorted, and signals can be edited, sorted, and routed.routed.

Also has profound input on motor Also has profound input on motor (via the basal ganglia and (via the basal ganglia and cerebellum) and cognitive function.cerebellum) and cognitive function.

Not all functions have been Not all functions have been elucidated.elucidated.

HypothalamusHypothalamus Fungsi:Fungsi:

Pusat kontrol autonomPusat kontrol autonom Influences HR, BP, resp. rate, Influences HR, BP, resp. rate,

GI motility, pupillary diameter.GI motility, pupillary diameter. Can you hold your Can you hold your

breath until you die?breath until you die? Respon Emotional Respon Emotional

Involved in fear, loathing, pleasureInvolved in fear, loathing, pleasure Drive center: sex, hungerDrive center: sex, hunger

Pengatur Suhu TubuhPengatur Suhu Tubuh Pengatur Masukan makananPengatur Masukan makanan

Contains a satiety centerContains a satiety center Pengaturan keseimbangan cairan dan hausPengaturan keseimbangan cairan dan haus Pengaturan siklus tidur/jagaPengaturan siklus tidur/jaga Pengontrol hormonPengontrol hormon

Releases hormones that influence hormonal Releases hormones that influence hormonal secretion from the anterior pituitary gland.secretion from the anterior pituitary gland.

Releases oxytocin and vasopressinReleases oxytocin and vasopressin

Limbic Limbic SystemSystem

Includes nuclei and tracts along the Includes nuclei and tracts along the border btwn the cerebrum and the border btwn the cerebrum and the diencephalon.diencephalon.

Functional grouping rather than Functional grouping rather than anatomicalanatomical

Functions include:Functions include:1.1. Establishing Establishing emotional emotional statesstates2.2. Linking conscious cerebral cortical Linking conscious cerebral cortical

functions w/ unconscious functions of the functions w/ unconscious functions of the brainstembrainstem

3.3. Facilitating memory storage and retrievalFacilitating memory storage and retrieval

• Limbic 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.

CerebellumCerebellum• Lies 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 neurons

• Has 2 primary functions:1. Adjusting the postural muscles of the body

• Coordinates rapid, automatic adjustments, that maintain balance and equilibrium

2. Programming and fine-tuning movements controlled at the subconscious and conscious levels• Refines learned movement patterns by regulating activity of both the

pyramidal and extrapyarmidal motor pathways of the cerebral cortex• Compares motor commands with sensory info from muscles and joints

and performs any adjustments to make the movement smooth

CerebellumCerebellum

The cerebellum can be The cerebellum can be permanently damaged permanently damaged by trauma or stroke or by trauma or stroke or temporarily affected temporarily affected by drugs such as by drugs such as alcohol.alcohol.

These alterations can These alterations can produce produce ataxiaataxia – a – a disturbance in balance.disturbance in balance.

Pembagian secara embriologis

Sistem Saraf PeriferSistem Saraf Perifer Menghubungkan timbal balik antara sistem saraf pusat Menghubungkan timbal balik antara sistem saraf pusat

dengan bagian-bagian tubuh.dengan bagian-bagian tubuh. Dapat dibagi menjadi:Dapat dibagi menjadi:

Divisi SensorisDivisi Sensoris Afferent Afferent

Menghantarkan sinyal dari reseptor ke SS Menghantarkan sinyal dari reseptor ke SS pusatpusat

Informasi berasal dari bagian dalam tubuh dan Informasi berasal dari bagian dalam tubuh dan dari luar dari luar

Serabut saraf sensoris terdiri dari Serabut saraf sensoris terdiri dari somaticsomatic (dari kulit, otot rangka atau sendi) atau (dari kulit, otot rangka atau sendi) atau visceralvisceral (organ2 organ dalam) (organ2 organ dalam)

Divisi MotorDivisi Motor Efferent Efferent

Menghantarkan sinyal/impuls dari SS pusat Menghantarkan sinyal/impuls dari SS pusat ke organ target/effector (muscles/glands)ke organ target/effector (muscles/glands)

Serabut saraf terdiri dari Serabut saraf terdiri dari SomatomotorikSomatomotorik bersifat VOLUNTARY (volunter/disadari) bersifat VOLUNTARY (volunter/disadari) menuju ke otot rangka ataumenuju ke otot rangka atau visceromotorik visceromotorik bersifat INVOLUNTARY (involunter/tak bersifat INVOLUNTARY (involunter/tak disadari) meniji ke otot polos, otot jantung disadari) meniji ke otot polos, otot jantung dan kelenjardan kelenjar

Peripheral nervous system

Pembagian secara fungsional