All about Medical

06 March 2009

Bio Electric

I. Potential membrane

Membrane potentialing to constitute potential that begat by marks sense distinctive content on the side in and membrane extern flank cell. Potential membrane really gets essential role in various cell function as cell of gland, afferent passing and other as it.

A. Membrane Potential

Process that gets role on potential is diffusion, transport is Na's active and leakage and k through membranes. Available 2 membrane potential conditions, which is potential action and resting is membrane (membrane rest term).

B. Diffusion

Happening diffusion because cell membrane character that semipermeabel, because of concentration in tall cell, ion k tend gets cell issue diffusion so reduce positive charge at deep danmembentuk elektropositif's cell outside cell and elektronegatif in cell. didusi is ion k terhenti after cell outboard condition have force enough (94 mV) to refuse its issue ion k from within despite cell concentrates ion k deep cell still by a long shot higher than openair cell. But Na's ion experience contrariwise condition, Na's ion diffusion that terhenti will afters reach potential difference as big as 61 mV. Tetapan as big as 94 mV divides ions k and 61mV divides Na's ions at conceive of Potential Nernst.

C. Goldman's equation

Goldman's equation declares for that:

If membrane gets permeabel's half character to some ion kind therefore effect potential developing diffusion process hinges on 3 factors:

  • electricity polarity each ion
  • membrane permeability
  • concentration each ion by the side of in and membrane extern flank

D. Transport Actives

Transport is active happens since mark sense Na's pump and k one gets elektrogenik's character because of more a lot of issue positive ion (3 ion Na will come out each 2 ion k inputs). This instance evoke tall concentration gradient among ion Na and ion k for capital first few that diffusion happening.

  • Na at in cell / Na cell outboard: 0,1
  • K at deep cell / k cell outboard: 35,0

E Membrane Potential conditions

E.1 Resting Potential Membrane

Resting is potential membrane constitute membrane potential while afferent cell lies on rest condition, usually as big as 90 mV. Factor that gets role on resting membrane covers:

  • Diffusion potential k(-94 mV)
  • Na's diffusion potential(+64 mV)
  • Na's pump k(-4 mV)

Action Potential

Action potential constitutes changing quick on potential membrane, cell component that gets role be Na's ion canal and ion canal K. Potential action consisting of umpteen phase, which is:

a. Rest phase (polarization)
b. Depolarisation
c. Repolarisasi

b. Depolarisation

Happening depolarisation because membrane suddenly becomes really permeabel to Na's ion, this permeability step-up can reach 500 until 5000 times of previous conditions so Na's ions drowns akson and makes potentials worked up presto toward positive (depolarisation), even on big afferent cell can went behind zero number.

c. Repolarisasi

With interrupts seperbeberapa puluh's time thousand increasing afters seconds Na's permeabilities, channel Na will be closed and channel k broad more openended than condition of previous so happening ion diffusion k membrane issue that back membrane condition on condition of before depolarisation.

F. Main components that get role on Potential Action

Main components that get role on potential action covers:

a. Na's canal
b . Canal k

a. Na's Canal

Na's canal consisting of activation gate at nurginal outer and inaktivasi's gate at nurginal deep. Activation gate is opened if few changed membrane potential more positive of 90 mV (about 70 mV). Gate inaktivasi will close automatic one about umpteen thousand setelahgerbang's seconds activation is opened and won't most reopen up to membrane potential was aptly most perfect polarizations.

b. Canals k

While is canal rest k in condition enclosed,canal will gently open many milidetik after channel Na is opened if changed potentials of 90 mV towards zero. Since its opening slowing canal k, therefore this canal will full open upon Na's canal starts to close. Its openended is this canal cause its issue ion k one ensues on gets its quick process replorisasi.

G. Positive After Potentials

Positive after is potential is membrane potential condition which more negative of condition of rest. milidetik's umpteen happening after gets finally action potential, slowing effect happening it ion canal foreclosure k and constitutes incorrect terminology ordinary effect historical factor in measurement ilmuan to membranes potential action.

H. Other Ion Roles in Potential Action

H.1 Anion

Anion is not permeabel to membrane channel, on hands to negative potential at deep cell if positive ion moves to come out membrane.

H.2 Ca's Ions

Nearly exhaustive body cell has to pump Ca, Ca's ion plays ball with or replace Na's ion in potential action. Ca's ion concentration membrane outboard 10.000 times over is even greater than concentrations in sel.e body Cell (particularly cardiac muscle and plain muscle) also have exposed Na Ca canal slower (10 - 20 slower times of Na's channels). If Ca's ion rate cell extra menurun, Na's channel becomes easier exposed (just meagrely changed of 90 mV). If Ca's ion rate 50% subnormal, can potential action happening at afferent perifer even without stimulus from outside.

I. Created Action Potentials

Up to nerve membrane be not been troubled won't happen action potential. If there is stimulus which make rise voltage


AditDot on Friday, March 06, 2009 said...

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