Biolistrik

Irfiansyah Irwadi

Outline

Bioelectricity • Action potential

@. Electrolyte @. depolarization@. RMP @. repolarization

• Electric signal recording@. Electrocardiograph (EKG)@. Electroencephalograph (EEG)@. Electromiograph (EMG)

Action potential

- 70 mV

+30 mV

- 55 mV

- 0 mV

Firing level

depolarization

repolarization

Action potential

Overshoot

Membran plasma

Lipid bilayer

Sifat : Semipermeabel

Fungsi : 1. Pemisah cairan ekstrasel dan intrasel2. Perlindungan bagian dalam sel terhadap lingkungannya3. Sarana transpor bahan-bahan yang akan masuk ke dalam sel atau

dikeluarkan oleh sel

Membran plasma

Composition :1. Protein (55%)

2. Lemak – Fosfolipid (25%)– Kolesterol (13%)– Lipid lain (4%)

3. Karbohidrat (3%)– Glikoprotein– Glikoloipid

Membran Sel

Electrolyte ECF vs ICF

Ion Plasma Interstisial Intracellular Direction

Na + 142 139 14 In

Ca ++ 1,3 1,2 <<< In

K + 4,2 4 140 Out

CL - 108 108 <<< / 4 In

ICF : intra cellular fluid (cytoplasm)ECF : extra cellular fluid (plasma + interstitial)

RMP (resting membrane potential)

• The difference of ion concentration between ECF & ICF electrial membrane gradient

• RMP = ± -70 till - 90 mv depend on cell

RMP : ICF is more negative than ECF-70 till -90 mv

+ + + +

- - - -++

- -

Stimulation

• Stimulation (electric or chemical) open voltage or ligand gated channel

• ECF & ICF is conected ion move influx or eflux increase or decrease membran potential

• Stimulation must be adequate, more than firing level

• Firing level : minimum intensity to stimulate depolarization

Copyright © Allyn & Bacon 2004

Membrane Potentials

1. Resting

Potential (just

described)

2. Excitato

ry Post-

synaptic potential

threshold4.

Inhibitory Post-

synaptic potential

3. Action

Potential

Excitatory Post-synaptic Potential (EPSP)

Post-synaptic neuron

Pre-synaptic neuron

1. The pre-synaptic neuron releases a neurotransmitter.

2. Neurotransmitter diffuses across extra-cellular space - synaptic cleft.

3. Neurotransmitter binds to post-synaptic receptor.

4. Binding of neurotransmitter causes Na+ channels in post-synaptic membrane to open.

5. Depolarization occurs (excitatory potential)

Post-synaptic neuron

Pre-synaptic neuron

Excitatory Post-synaptic Potential (EPSP)

14

OUTSIDE

INSIDE

K+ = Potassium; Na+ = Sodium; Cl- = Chloride; Pr- = proteins

Na+

Na+

K+

K+

Force of Diffusion

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - -

Cl-

Force of Diffusion

Cl-

Pr-

Closedchannel

openchannel

openchannel

nochannel

OPEN Na+CHANNEL

+ + +

- 65 mV- 50 mV

1. Resting Membrane PotentialExcitatory Post-Synaptic Potential (EPSP)

EPSP

• EPSP is a “graded” potential• Multiple EPSPs are integrated across

space and time.

Excitatory Post-synaptic potential

Integration

• Once the threshold is reached, voltage-dependent sodium channels are opened

• The cell is depolarized (action potential)

Electric stimulation

Na+ channel opened

Na+Na+ channel

closed

Membrane

Cell

Fast response channel : fast opened and closed, ex : NaVoltage gated ion channel

Electric sensor

Electric stimulation

K+ channel opened

K+

K+ channel closed

Membrane

Cell

Slow response channel : late in opened and closed, ex : Ca & KVoltage gated ion channel

Electric sensor

Chemical stimulation

Cl- channel opened

Cl-

K+ channel closed

Membrane

Cell

Ligand gated channel, slow in response ex : ClChemical substance : GABA, benzodiazepine

receptor

Ligand

Stimmulation↓

Fast natrium channel is opened↓

Natrium influx↓

membrane potential decrease↓

Depolarization↓

Fast natrium channel closed & Slow kalium channel opened

↓Kalium eflux

↓ membran potential back increase

↓repolarization

Cl- ligand gated Channel complex

Cl-

Action potential

- 70 mV

+30 mV

- 55 mV

- 0 mV

Firing level

depolarization

repolarization

Action potential

Overshoot

Electrical stimulation : stimulate at the same time but in the different quick response

Fast response Slow response

Na channel open

depolarization

Ca channel open

Cl channel open

K channel open

repolarization

Depolarization Vs Repolarization

• Depolarization : decrease in membrane potential, approaching zero (0 mv)

• Depolarization natrium influx

• Repolarization : increase in membrane potential, back to the RMP

• Repolarization kalium eflux

After potential

Inwarding Na & outwarding K are trapped

↓Positif after potensial

↓Danger

↓Stimulate Na/K ATP ase pump

↓Active Transport

↓Decrease in Membrane

potential ~ RMP

RMP

FL

0

PRA PRR

Refracted Periods

• Periods when cell become insensitive even stimulate again

• Refracted periods :

@. Absolute :

when depolarization

@. Relatif :

when repolarization, need higher intensity

RMP

FL

0

PRA PRR

Hipopolarisasi

mvolt

- 55

- 70

Firing level

RMP

Hiperpolarisasi

Propagation

• Conducting action potential through the membrane

• By stimulation on electric sensor of fast natrium channel

• So there is electrical conduction

Plateau in action potential

Plateau delay on repolarization, which sign as steady state after depolarization Because of 2 factors : @ Delay on kalium channel opening or@ Slow natrium-calcium channel open (it only in cardiac and smooth muscle

Action potential

• Spike• Neuron, skeletal

muscle

• Plateau• Cardiac muscle,

smooth muscle

Cardiac muscle

StimulationNa–Ca channel

complex

Fast Na Channel open first

Slow Ca Channel

Open later

Quick depolarization

Plateau

Chapter 4 Principles of Neural and Hormonal CommunicationHuman Physiology by Lauralee Sherwood ©2010 Brooks/Cole, Cengage Learning

Electrical signal recording

EMG, EEG, EKG

Electromiogram (EMG)

• record electrical signal from peripheral neuron and skeleltal muscle

• EMG consist of a protrude which administered to the muscle & completed by electrical stimulator

• EMG is used to measure function & diagnose neuron & muscle disturbaces, ex : myasthenia gravis, polio & paralysis

Electroencefalogram (EEG)

• Record electrical signal from brain or CNS• EEG consist of some electrodes which putted in

head• EEG is used to evaluate brain function &

diagnose in brain disturbances, ex : sleep disorder & epilepsy

Electrocardiogram (ECG)

• ECG record in cardiac electricity, depolarization & repolarization

• The recording is a result of electrical vector which in one direction

• These show cardiac axis and cardiac apex location

Depend on electrode location ?

Depolarization/ repolarization ventrikel

Deflect +

Deflect -

Bifasic

Elektrodes

• Unipolar

@. Augmented : aVR, aVL, aVF

@. Chest : V1-6

• Bipolar

Lead I

Lead II

Lead III

Lead II recording

P wave atrium depol

qrs complex ventrikel depol

t waveVentrikel repol

Question :atrium Repol..?

Why t wave (Ventr repol) defleksi + ?