Sistem_Saraf_2023.pdf

By: apt. Ridho Islamie, S.Farm., M.Si., Ph.D.  Tujuan Pembelajaran: Mahasiswa diharapkan… Mampu mengklasifikasikan sistem saraf Mampu memahami anatomi dan fisiologi sel saraf (neuron) Mampu menjelaskan fisiologi neuroglia Mampu memahami mekanisme potensial aksi Mampu memahami mekanisme...

By: apt. Ridho Islamie, S.Farm., M.Si., Ph.D.  Tujuan Pembelajaran: Mahasiswa diharapkan… Mampu mengklasifikasikan sistem saraf Mampu memahami anatomi dan fisiologi sel saraf (neuron) Mampu menjelaskan fisiologi neuroglia Mampu memahami mekanisme potensial aksi Mampu memahami mekanisme komunikasi antar saraf Mampu memahami jenis, fungsi dan transmisi neurotransmitter dalam sistem saraf termasuk beberapa reseptor spesifiknya Mampu memahmi perbedaan anatomi dan fisiologi otak dan sum-sum tulang belakang Mampu memahami perbedaan anatomi dan fisiologi sistem saraf perifer Mampu memahami perbedaan sistem saraf simpatis dan sistem saraf parasimpatis  Klasifikasi Sistem Saraf Sel Saraf Jaringan Saraf Potensial Aksi Outline Komunikasi Antar Sel Saraf Neurotransmitter Sistem Saraf Pusat (CNS): Brain and Spinal Cord Sistem Saraf Perifer (PNS): Somatic and Autonomic  Nervous System Peripheral Central Nervous Nervous System System (CNS) (PNS) Brain Afferent Division Efferent Division Nervous System Classification Somatic Nervous Autonomic Spinal Cord Nervous System System (SNS) (ANS) Sympathetic Nervous System Parasympathetic Nervous System Functions of the Nervous System Sensory function: Motor function: Once Sensory receptors sensory information is detect internal stimuli, Integrative function: integrated, the nervous such as an increase in The nervous system system may elicit an blood pressure, or processes sensory appropriate motor external stimuli (for information by response by activating example, a raindrop analyzing it and making effectors (muscles and landing on your arm). decisions for glands) through cranial This sensory appropriate responses - and spinal nerves. information is then an activity known as Stimulation of the carried into the brain integration. effectors causes and spinal cord through muscles to contract and cranial and spinal glands to secrete. nerves. Neuron Cell A Structural Classification of Neurons  Functional Classification of Neurons Sensory or afferent neurons: which transmit impulses toward the CNS Motor or efferent neurons which transmit impulses away from the CNS Interneurons or association neurons are mainly located within the CNS between sensory and motor neurons, which process sensory input and coordinate motor responses, lie entirely within the central nervous system NEUROGLIA CELL  Ependymal Cells assist in producing, circulating, and monitoring cerebrospinal fluid (CSF) Astrocytes Neuroglia Maintain blood–brain barrier (BBB); provide structural Cell in support; regulate ion, nutrient, and dissolved- gas Central concentrations; absorb and recycle neurotransmitters; form scar tissue after injury Nervous System Oligodendrocytes Myelinate CNS axons; provide structural framework Microglia Remove cell debris, wastes, and pathogens by phagocytosis  regulate O2, CO2, Satellite nutrient, and Neuroglia Cells neurotransmitter levels around neurons in ganglia Cell in Peripheral Nervous Surround all axons in System Schwann PNS; responsible for myelination of peripheral Cells axons; participate in repair process after injury  IRRITABILITY CONDUCTIVITY SEL SARAF KEMAMPUAN KEMAMPUAN MEMPUNYAI 2 MERESPON MEMINDAHKAN STIMULUS & IMPULS LISTRIK FUNGSI MENGUBAHNYA KE SEL SARAF UTAMA : MENJADI YANG LAIN ATAU IMPULS LISTRIK KE EFEKTOR (OTOT DAN KELENJAR)  STIMULUS YANG DATANG HARUS DIUBAH MENJADI IMPULS LISTRIK MELALUI PROSES POTENSIAL AKSI IRRITABILITY PROSES POTENSIAL AKSI MELIBATKAN PERISTIWA- PERISTIWA : RESTING POTENTIAL, DEPOLARISASI, REPOLARISASI  POTENSIAL AKSI DIHANTARKAN MELALUI AKSON MELIBATKAN DIFUSI ION-ION EKSTRA DAN INTRA SEL SARAF HANTARAN POTENSIAL AKSI MEMPUNYAI HUKUM : ALL OR NONE CONDUCTIVITY PADA AKSON YANG BERMIELIN: POTENSIAL AKSI BERJALAN DARI NODUS RANVIER YANG SATU KE NODUS YANG LAIN = SALTATORY CONDUCTION PADA AKSON YANG TIDAK BERMIELIN : POTENSIAL AKSI BERJALAN SEPANJANG AKSON.  Ion Channels in Neurons: 1. Leak Channel Gated channels that randomly open and close. Found in nearly all cells, including dendrites, cell bodies, and axons of all types of neurons.  Ion Channels in Neurons: 2. Ligand-gated Channel Gated channels that open in response to binding of ligand (chemical) stimulus Dendrites of some sensory neurons such as pain receptors and dendrites and cell bodies of interneurons and motor neurons.  Ion Channels in Neurons: 3. Mechanically-gated Channel Gated channels that open in response to mechanical stimulus (such as touch, pressure, vibration, or tissue stretching). Dendrites of some sensory neurons such as touch receptors, pressure receptors, and some pain receptors.  Ion Channels in Neurons: 4. Voltage-gated Channel Gated channels that open in response to voltage stimulus (change in membrane potential). Axons of all types of neurons Resting Potential: Potensial membran yang terdapat pada instrasel ketika sel saraf dalam keadaan istirahat pada umumnya bermuatan negatif sebesar -70 mV Ion Na+: bermuatan positif, Ion K+: bermuatan positif, Ion Cl-: bermuatan negatif, Ion Ca2+: bermuatan positif RESTING POTENTIAL Ion Na+: bermuatan positif, Ion K+: bermuatan positif, Ion Cl-: bermuatan negatif, Ion Ca2+: bermuatan positif  ACTION POTENTIALS: THRESHOLD Martini: - 60 mV Tortora: - 55 mV If a stimulus is strong enough to depolarize the membrane to a critical level referred to as threshold Once threshold is reached, the continued depolarization takes place automatically.  Generation of an Potential Action 1. 2. Resting State Depolarizing phase 4. 3. Repolarization phase continues Repolarizing phase begins  ACTION outflow of potassium ions (K+) causes the repolarizing phase of an action POTENTIALS: potential. Inflow of sodium ions (Na+) causes the depolarizing phase Berkurangnya perbedaan potensial pada Depolarisasi menyebabkan penerusan membrane sel antara intra dan ekstra sel potensial aksi sepanjang sel saraf, menyebabkan terjadinya Depolarisasi yang Hiperpolariasi menyebabkan penghambatan penting dalam potensial aksi sepanjang sel saraf penerusan potensial tersebut Bagaimana Cara Antar Sel Saraf Berkomunikasi? Signal Transmission at Synapses (a region where communication occurs between two neurons or between a neuron and an effector cell) Tahap Komunikasi Antar Saraf 1. Potensial Aksi mencapai Ujung Terminal Akson à Kanal Ion Ca2+ terbuka 2. Ion Ca2+ masuk ke dalam pra sinaps à mendorong Vesikel menuju ujung membrane pra sinaps 3. Vesikel mengalami eksositosis untuk merilis neurotransmitter ke celah sinaps 4. Dicelah sinaps Neurotransmitter menuju membrane post sinaps. 5. Di membrane post sinaps Neurotransmiter berikatan dengan reseptor (yang terikat pada kanal ion Na). 6. Kanal ion Na+ terbuka à Ion Na masuk ke dalam membrane post sinaps à tjd Depolarisasi membrane post sinaps à Potensial Aksi diteruskan ke sel saraf berikutnya  Neurotransmitter Classification Based on their effects on postsynaptic membranes, neurotransmitters are often classified as excitatory or inhibitory. Excitatory neurotransmitters cause depolarization and promote the generation of action potentials; whereas Inhibitory neurotransmitters cause hyperpolarization and suppress the generation of action potentials. The effect of a neurotransmitter on the postsynaptic membrane depends on the properties of the receptor, not on the nature of the neurotransmitter.  Acetylcholine (ACh) Glutamate (Glu) Gamma-aminobutyricacid(GABA) Neurotransmitter: Small-Molecule Norepinephrine (NE) Neurotransmitters Epinephrine (E) Dopamine (DA) Serotonin: 5-hydroxy- tryptamine (5-HT) GOLONGAN CATECHOLAMINES: DOPAMINE, NOR-EPINEPHRINE, EPINEPHRINE GOLONGAN MONOAMINE: SEROTONIN Neurotransmitter 1. Synthesis in the presynapse 2. Storage inside the vesicles via vesicular transporter 3. Release out to the synaptic cleft 4. Bind to the Receptor at Pre-synaptic or Post-synaptic membrane 5. Enzymatic Degradation: in the synaptic cleft or in the presynaptic membrane 6. Reuptake into presynaptic membrane using the transporter or into glial cell Gamma-aminobutyricacid Cl- Cairan Ekstrasel Cl- Cl- (GABA) GABA à Neurotransmiter penghambat (inhibitorik) utama di otak Sintesis dari Glutamat dengan enzim Glutamat Dekarboksilase Glutamate à Glutamat Dekarboksilase à GABA 3 reseptor GABA: GABAA, GABAB, GABAc GABAA & GABAc à Reseptor yang terikat dengan kanal Ion Cl- Aktivasi reseptor GABA oleh neurotransmitternya à kanal ion Cl terbuka à hiperpolarisasi à penghambatan potensial aksi Sitoplasma Cl- Cl- Degradasi: Enzim GABA Transaminase Reuptake: GABA Transporter  GABA Transmission Pathway Glutamate Glutamat : neurotransmitter pemicu (excitatory) utama di otak Tidak menembus sawar otak dan tidak disuplai dari sistem sirkulasi Disintesis di presinaptik otak melalui prekusor: 1. Glutamin à Glutaminase à Glutamat 2. Aspartat à transaminase à Glutamat Glutamat disimpan didalam vesikel melalui vesicular glutamate transporter Glutamat Reuptake Transporter à Reuptake membran presinaptik & sel glia (glutamat à glutamin sintetase à glutamin) Reseptor glutamat, ada 3 kelompok utama: 1. NMDA (N-methyl-D-aspartat) 2. AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazile propionic acid) 3. Kainate RESEPTOR Glutamat Terikat kanal ion Na dan Ca Aktivasi reseptor à pembukaan kanal ion Na & Ca à konsentrasi Na dan Ca sel meningkat à hipereksitasi impuls saraf  Glutamate Transmission Pathway Serotonin: 5-hydroxy-tryptamine (5-HT) 5-HT is concentrated in the neurons in a part of the brain called the raphe nucleus. It Involved in sensory perception, temperature regulation, control of mood, appetite, and the induction of sleep. Receptor: 5-HT1, 5-HT2, 5-HT3 : Terikat kanal Ion Reuptake: Serotonin Reuptake Transporter Enzyme Degradation: Monoamin Oksidase (MAO) dan catechol-O- methyltransferase (COMT)  Serotonin Transmission Pathway Dopamine (DA) a CNS neurotransmitter released in many areas of the brain Brain neurons containing the neurotransmitter dopamine (DA) Active during motional responses (Locomotor Activity), addictive behaviors, and pleasurable experiences dopamine-releasing neurons help regulate skeletal muscle tone and some aspects of movement due to contraction of skeletal muscles Synthesis: Tyrosine à DOPA à Dopamine Receptor: D1 & D2 à Tidak Terikat Kanal Ion Dopamine Degradation: catechol-O-methyltransferase (COMT) dan monoamine oxidase (MAO)  Dopamine Transmission Pathway RECEPTORS IN NERVOUS SYSTEM RESEPTOR TERIKAT KANAL ION RESEPTOR TERGANDENG PROTEIN-G Disebut juga Reseptor Disebut juga Reseptor Ionotropik (Ligand-gated ion Metabotropik channel receptor) Yang termasuk: Yang termasuk: Reseptor Muskarinik (Ach) Reseptor Nikotinik (Ach) Reseptor Adrenergik Reseptor Reseptor GABAA Reseptor Dopamin Reseptor Glutamat Reseptor 5-HT3 (SEROTONIN)  Peripheral Nervous System (PNS) Afferent Division Efferent Division Peripheral Autonomic Nervous Somatic Nervous Nervous System System System (SNS) (ANS) Classification Sympathetic Nervous System Parasympathetic Nervous System  1. Afferent division carries sensory information toward the CNS: Involved Sensories Receptor: mekanoreseptor, The PNS kemoreseptor, termoreseptor, nosiseptor consists of 2. Efferent division two divisions carries motor information away from the CNS toward the effector tissues (muscles and glands). Terbagi menjadi: Sistem saraf somatik dan sistem saraf otonom  Efferent Division in PNS  Efferent division: Somatic Nervous System Voluntary: Pergerakan disadari Organ Utama: Otot Skeletal Neurotransmitter: Asetilkolin Tidak ada preganglion dan postganglion  Efferent division: Autonomic Nervous System Involuntary: Pergerakan atau aktivitas tidak disadari Organ: Otot jantung, Otot Polos, dan Kelenjar. Neurotransmitter: Parasimpatis: Asetilkolin Simpatis: Noradrenalin Ada Preganglion dan Postganglion Preganglion: myelinated à rlis ACh Postganglion: unmyelinated  Sympathetic VS Parasympathetic Some organs are innervated by just one division, But most vital organs receive dual innervation, so they receive instructions from both the sympathetic and parasympathetic divisions. Where dual innervation exists, the two divisions commonly have opposing effects Dual innervation: Opposing effects is most obvious in the digestive tract, heart, and lungs Martini 9th Ed, p.532, Tortora, 14th Ed. p.540 à WAJIB BACA Cholinergic Neurons and Receptors Parasympathetic Release the neurotransmitter Acetylcholine (ACh) ACh is stored in synaptic vesicles and released by exocytosis It then diffuses across the synaptic cleft and binds with specific Cholinergic Receptors The two types of cholinergic receptors, both of which bind ACh, are Nicotinic receptors and Muscarinic receptors Muscarinic subtype receptor: M1 – M5 à Metabotropic receptor Nicotinic receptor à Ionotropic receptor  The Sequence of Events at a Typical Cholinergic Synapse: Synaptic Activity Adrenergic Neurons and Receptors Sympathetic Adrenergic neurons: release nor-epinephrine (NE), also known as noradrenalin NE Synthesis: Tyrosine à Dopa à Dopamine à nor-epinephrine (NE) NE and E Degradation: catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO) NE is stored in synaptic vesicles and released by exocytosis Adrenergic receptors bind both norepinephrine and epinephrine. Adrenergic Receptors: Alpha receptors (𝜶) and Beta receptors (𝜷) Adrenergic Receptors: Metabotropik Receptors Subtypes Receptors à 𝜶1, 𝜶2, 𝜷1, 𝜷2, and 𝜷3 THANK YOU !!! SEE YOU NEXT WEEK