Biofisika Neuron

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Tentang Biofisika Neuron Universitas Airlangga

Text of Biofisika Neuron

  • BIOFISIKA NEURON(Biophysics of Neuron)

    Aqsa SjuhadaDept of Physiology / Oral Biology, Airlangga University@aqsas

    http://aqsas.blogspot.com

  • Biofisika Neuron 2

    BODY LIQUID

    Total : 60%

    Intracellular: 40%

    Extracell: 20% (kecuali cair serebrospinal, cairansendi, cairan saliva)

    - cairan interstitial 15%

    - cairan plasma 5%

    - cairan sel darah

    - cairan intra vaskuler

  • Biofisika Neuron 3

    TRANSPORT BAHAN

    ACTIVE TRANSPORT

    1. primary

    2. secondary

    - bulk transport

    - exocytosis

    - endocytosis

    - phagocytosis

    - pinocytosis

    PASSIVE TRANSPORT

    - osmosis

    - diffusion

    - filtration

    -solvent drag

  • Biofisika Neuron 4

    ACTIVE

    TRANSPORT

    PASSIVE

    TRANSPORT

    CELLULAR

    ENERGY

    required not required, only

    kinetic energy

    PROCESS physiology -

    biology

    physics

  • Biofisika Neuron 5

    DIFFUSION

    Particle movement

    Simple diffusion : O2, CO2, alcohol

    Facilitated diffusion : glucose, amine acid

    OSMOSIS Liquid movement

    Hypotonic - Hypertonic

  • Biofisika Neuron 6

    DIFFUSION

  • Biofisika Neuron 7

    OSMOSIS

  • Biofisika Neuron 8

    MACAM GERAKAN

    DARI

    ARAH

    GERAKAN

    PLASMA

    MEMBRAN

    CARRIER

    SYSTEM

    ENERGY

    CELLULAR

    Osmosis Solvent CC SP Tidak Tidak

    Diffusi Solut CC +/- Tidak Tidak

    Active

    Transp

    Solut CC SP Ada Ada

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  • Biofisika Neuron 11

    eyeem.com/aqsa

  • Biofisika Neuron 12

    SEL EKSITABEL

    Sel yg mampu menimbulkan / menjalankan

    impuls elektrokimia sepanjang membran

    plasmanya.

    Sel saraf, sel otot, sel kelenjar

  • Biofisika Neuron 13

    MEMBRAN PLASMA

    STRUKTUR DAN KOMPOSISI MEMBRAN PLASMA

    Lemak dynamic mozaic design / lipid bilayer 42%

    Protein 55%

    Karbohidrat 3%

  • Biofisika Neuron 14

    SIFAT

    - Elastis tipis, ketebalan 6-10nm

    FUNGSI

    - Physical isolation

    - Regulation of exchange with the environment ---nutrition, ion

    - Sensitivity --- receptor function

    - Structural support

    JENIS

    - Impermeable

    - Semi permeable

    - Selective permeable

  • Biofisika Neuron 15

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    PROTEIN

    Sebagian besar glicoprotein

    Protein integral / protein perifer, fungsinya:

    membatasi pergerakan membran plasma

    sebagai channel

    carrier system

    enzyme

    receptor

    Karbohidrat; berada di luar berikatan dg glicoprotein

    maupun lipid bilayer, fungsi: sebagai indikator sel.

  • Biofisika Neuron 17

    NEURON

    = Sel saraf

  • Biofisika Neuron 18

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    Dentrites

    Cell Body

    Axon

    Terminal

    A Typical Neuron Overview

  • Biofisika Neuron 20

    Diverse Neuron Forms and Functions

  • Biofisika Neuron 21

    Basic Concepts

    Volt

    A charge difference between two points in space

  • Biofisika Neuron 22

    Basic Concepts

    Ions charged particles

    Anions Negatively charged particles

    Cations Positively charged particles

  • Biofisika Neuron 23

    Basic Concepts

    Forces that determine ionic movement

    Electrostatic forces

    Opposite charges attract, Identical charges repel

    Concentration forces

    Diffusion movement of ions through semipermeable membrane

    Osmosis movement of water from region of high concentration to low

    Hydrostatic Forces

    Gravity forces upon osmosis

    The combination of these forces leads to dynamic equilibrium in the cellular environment

  • Biofisika Neuron 24

    POTENSIAL MEMBRAN

    Perbedaan muatan listrik di luar dan di dalam membran sel

    RMP

    =Resting Membran Potential

    =Potensial Membran Istirahat

    Berbedaan muatan listrik di luar dan di dalam membran sel dalam keadaan tidak ada aktivitas elektris.

  • Biofisika Neuron 25

  • Apa penyebab Resting Membrane

    Potential mempunyai beda

    potensial -70 mV ?

    Adanya perbedaan distribusi ion di luar dan

    di dalam membran sel, terutama ion K+

    dan Na+

    Biofisika Neuron 26

  • Biofisika Neuron 27

    Perbedaan distribusi ion di luar dan di dalam

    membran

  • Biofisika Neuron 28

    Besar RMP 70 mV

    Artinya ?

    Potensial elektriks di dalam membran sel lebih negatif dibandingkan di luar membran sel sebesar 70mV

  • Biofisika Neuron 29

    eyeem.com/aqsa

  • Biofisika Neuron 30

    RANGSANGAN

    Adekuat Tidak adekuat

    Mencapai threshold Tidak mencapai

    threshold

    POTENSIAL AKSI LOCAL POTENTIAL

    Dirambatkan ke segala arah Tidak dirambatkan

    Hukum ALL OR NONE Sumasi

  • Rangsangan menyebabkan

    Natrium+ influx

    Biofisika Neuron 31

  • Biofisika Neuron 32

    Action Potential Sequence

    Involves the action of voltage-gated channels

    Exchanges of ions in and out of the cell

  • Biofisika Neuron 33

    Action Potential Stages: Overview

  • Biofisika Neuron 34

    ANIMASI ACTION POTENTIAL

  • Biofisika Neuron 35

    Action Potential

    Sequence

    Saluran Na+ terbuka, terjadilah fast natrium

    influx, depolarisasi.

  • Biofisika Neuron 36

    Action Potential

    Sequence

    Pada keadaan +40 mV, saluran Na+ menutup, tetapi saluran K+ sekarang terbuka, menyebabkan pengeluaran ion K+ (gradien konsentrasi), menyebabkan penurunan gradien elektris.

  • Biofisika Neuron 37

    Action Potential

    Sequence

    Saluran K+ menutup, terjadilah akumulasi ion K+ di ekstrasel. Hal ini menyebabkan depolarisasi, sedemikian rupa sehingga terjadi undershoot pada akhir action potential

    Equilibrium

    membran

    potential

    dikembalikan

  • Biofisika Neuron 38

    Action Potential

    Sequence

    Na+-K+ pump (pompa Na+-K+) berfungsi

    mengembalikan keadaan serupa, yaitu RMP.

  • Biofisika Neuron 39

  • Biofisika Neuron 40

    Membrane & Channel Changes during an

    Action Potential

  • Biofisika Neuron 41

    Refractory Period

    Two types

    Absolute

    When Na+ channels close, at peak of AP, they

    do not reopen for a time

    Relative

    Membrane hyperpolarized

    Some Na+ channels still refractory

  • Biofisika Neuron 42

    Propagation of the Action Potential

    Action Potential spreads down the axon in a

    chain reaction

    Unidirectional

    it does not spread into the cell body and

    dendrite due to absence of voltage-gated

    channels there

    Refraction prevents spread back across axon

  • Biofisika Neuron 43

    Propagation of the Action Potential

    Speed of propagation varies with the axon

    diameter

    Faster with larger axons

    In large axons of mammals

    5m/second 2um axons

    20m/second in 20um axons

  • Biofisika Neuron 44

    Propagation of the Action Potential

    Speed of propagation also assisted by the

    myelin sheath

    Provides resistance to AP

    Regular gaps in the myelin sheath (1mm

    intervals)

    Nodes of Ranvier

    Increase conduction speed up to 15 times

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  • Biofisika Neuron 48

  • Terima Kasih

    Biofisika Neuron 49

    www.flickr.com/humanis

    Blue trees, Seattle, WA