POTENSIAL AKSI

Oleh :

Drg. Berlian Bidarisugma

NERVOUS SYSTEM

Peripheral NS :Nn. CranialisNn. Spinalis

Central NS :Otak &Medulla spinalis

Autonomic NS :Sympathetic NS

Parasympathetic NS

Excitable cell

Neuron Myocyte = Muscle cell

Neuron

Signal transduction

Message / stimulus / substance / Hormone / Cytokine / Zat

RECEPTOR first messenger

(membrane cell / organells )

Bahan / substant : second messenger

Characteristic excitability tissue

Stimulus

Neurolemma = membrane cell of neuron

Action Potential

conduction

Ions for action potential

1. Natrium

channel : open n close rapidly

2. Kalium

channel : open n close slowly

- 70 mV

+30 mV

- 55 mV

- 0 mV

Firing level

repolarization

depolarization

Action potential

Overshoot

ACTION POTENTIAL

1.Stimulus

2.Cannel Na+ open : Na+ influx

3.Depolarization

4.Channel Na+ close

5.Cl- influx : first repolarization

6.Channel K+ open : K+ efflux

7.Repolarization

Na+

gate

Closed

Na+

Na+

Opened

Voltage – gated sodium channels

amyelin axon

+ +

+

+ +

- --

- -

Potensial aksi

Action Potential

Node of Ranvier

Saltatory conduction

myelin axon

Schwann cell

neuroglia – type : oligodendrocyte

Function : - Protect for neuron- Form myelin sheath

Firing level

Time

Potensial Lokal

NA

0mVolt

Summasi

Potensial aksi

Types of stimulus

1.Subliminal : local potential

2.Liminal : action potential

3.Supraliminal : sda

Action potential

1. Follow ‘All or None’2. Propagation 3. No summasi

Local potential

1. No ‘All or None’2. No propagation 3. summasi

Summasi

Potensial aksi

Potensial lokal

Axon

Propagation

Action potential

Hipopolarisasi

mvolt

- 55

- 70

Firing level

RMP

Hiperpolarisasi

Na+

Na+

Na+

+Bgate

Opened

Closed

SELAMAT BELAJAR