absolute refractory period

絶対不応期

WordNet

1. something that is conceived or that exists independently and not in relation to other things; something that does not depend on anything else and is beyond human control; something that is not relative; "no mortal being can influence the absolute"
2. perfect or complete or pure; "absolute loyalty"; "absolute silence"; "absolute truth"; "absolute alcohol"
3. complete and without restriction or qualification; sometimes used informally as intensifiers; "absolute freedom"; "an absolute dimwit"; "a downright lie"; "out-and-out mayhem"; "an out-and-out lie"; "a rank outsider"; "many right-down vices"; "got the job through sheer persistence"; "sheer stupidity" (同)downright, out-and-out, rank, right-down, sheer
4. not capable of being violated or infringed; "infrangible human rights" (同)infrangible, inviolable
5. expressing finality with no implication of possible change; "an absolute guarantee to respect the nations authority"
6. not limited by law; "an absolute monarch"
7. a unit of geological time during which a system of rocks formed; "ganoid fishes swarmed during the earlier geological periods" (同)geological period
8. (ice hockey) one of three divisions into which play is divided in hockey games
9. the end or completion of something; "death put a period to his endeavors"; "a change soon put a period to my tranquility"
10. the interval taken to complete one cycle of a regularly repeating phenomenon
11. a punctuation mark (.) placed at the end of a declarative sentence to indicate a full stop or after abbreviations; "in England they call a period a stop" (同)point, full_stop, stop, full point
12. temporarily unresponsive or not fully responsive to nervous or sexual stimuli; "the refractory period of a muscle fiber"
13. not responding to treatment; "a stubborn infection"; "a refractory case of acne"; "stubborn rust stains" (同)stubborn
14. (Persian folklore) a supernatural being descended from fallen angels and excluded from paradise until penance is done
15. a beautiful and graceful girl

PrepTutorEJDIC

1. 『まったくの』,完全な(complete) / 『絶対的な力を持った』,絶対の / 確かな,確固とした(certain) / 無条件の,制約のない / (文法で)独立の,単独の
2. (あることが続く)『期間』 / (歴史的な)『時代』 / (試合の)『一区切り』,ピリオド / 授業時間,時限: / (循環して起こる現象などの)周期 / (回転運動などの)周期 / 紀(地質時代の区分の一つ;era(代)の下,epoch(世)の上) / 《おもに米》『ピリオド』,終止符(《英》full stop;Mr.,U.S.など略語の符号(.)も含む) / 《複数形で》《文》掉尾(とうび)文(多くの節から成り,論理的に緊密な構成をもっている文) / 《名詞の前にのみ用いて》ある時代[特有]の,時代物の / (文の終わりに感嘆詞的に)以上,終わり・月経（期間）
3. (人などが)手に負えない,強情な / (病気が)治りにくい,がんこな / (金属などが)溶けにくい,耐火性の
4. 屈折媒体(レンズ) / =refracting telescope

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/02/27 16:34:18」(JST)

wiki en

[Wiki en表示]

This article is about refractory periods in physiology. For sexual refractory periods, see refractory period (sex).

Refractoriness is the fundamental property of any object of autowave nature (especially excitable medium) not to respond on stimuli, if the object stay in the specific refractory state. In common sense, refractory period is the characteristic recovery time, a period of time that is associated with the motion of the image point on the left branch of the isocline (for more details, see also Reaction-diffusion and Parabolic partial differential equation).

Schematic of an electrophysiological recording of an action potential showing the various phases that occur as the wave passes a point on a cell membrane.

In physiology, a refractory period is a period of time during which an organ or cell is incapable of repeating a particular action, or (more precisely) the amount of time it takes for an excitable membrane to be ready for a second stimulus once it returns to its resting state following an excitation. It most commonly refers to electrically excitable muscle cells or neurons. Absolute refractory period corresponds to depolarisation and repolarisation, whereas relative refractory period corresponds to hyperpolarisation.

Electrochemical usage

See also: Action potential

After initiation of an action potential, the refractory period is defined two ways:

• The absolute refractory period is the interval during which a second action potential absolutely cannot be initiated, no matter how large a stimulus is applied.
• The relative refractory period is the interval immediately following during which initiation of a second action potential is inhibited but not impossible.

The absolute refractory period coincides with nearly the entire duration of the action potential. In neurons, it is caused by the inactivation of the Na⁺ channels that originally opened to depolarize the membrane. These channels remain inactivated until the membrane hyperpolarizes. The channels then close, de-inactivate, and regain their ability to open in response to stimulus.

The relative refractory period immediately follows the absolute. As voltage-gated potassium channels open to terminate the action potential by repolarizing the membrane, the potassium conductance of the membrane increases dramatically. K⁺ ions moving out of the cell bring the membrane potential closer to the equilibrium potential for potassium. This causes brief hyperpolarization of the membrane, that is, the membrane potential becomes transiently more negative than the normal resting potential. Until the potassium conductance returns to the resting value, a greater stimulus will be required to reach the initiation threshold for a second depolarization. The return to the equilibrium resting potential marks the end of the relative refractory period.

Cardiac refractory period

Effective Refractory Period

The refractory period in cardiac physiology is related to the ion currents that, in cardiac cells as in nerve cells, flow into and out of the cell freely. The flow of ions translates into a change in the voltage of the inside of the cell relative to the extracellular space. As in nerve cells, this characteristic change in voltage is referred to as an action potential. Unlike that in nerve cells, the cardiac action potential duration is closer to 100 ms (with variations depending on cell type, autonomic tone, etc.). After an action potential initiates, the cardiac cell is unable to initiate another action potential for some duration of time (which is slightly shorter than the "true" action potential duration). This period of time is referred to as the refractory period, which is 250ms in length and helps to protect the heart.

In the classical sense, the cardiac refractory period is separated into an absolute refractory period and a relative refractory period. During the absolute refractory period, a new action potential cannot be elicited. During the relative refractory period, a new action potential can be elicited under the correct circumstances.

The cardiac refractory period can result in different type of re-entry, which is considered as a main cause of many kinds of tachycardia. As a sort of re-entry, the vortices of excitation in the myocardium (autowave vortices) is considered to be the main mechanism of life-threatening cardiac arrhythmias. In particular, the autowave reverberator is a typical in thin walls of the atria, with the auricular flutter producing.

Neuronal refractory period

The refractory period in a neuron occurs after an action potential and generally lasts one millisecond. An action potential consists of three phases.

Phase one is depolarization. During depolarization, voltage-gated sodium ion channels open, increasing the neuron's membrane conductance for sodium ions and depolarizing the cell's membrane potential (from typically -70 mV toward a positive potential). In other words, the membrane is made less negative. After the potential reaches the activation threshold (-55 mV), the depolarization is actively driven by the neuron and overshoots the equilibrium potential of an activated membrane (+30 mV).

Phase two is repolarization. During repolarization, voltage-gated sodium ion channels inactivate (different from the close state) due to the now-depolarized membrane, and voltage-gated potassium channels activate (open). Both the inactivation of the sodium ion channels and the opening of the potassium ion channels act to repolarize the cell's membrane potential back to its resting membrane potential.

When the cell's membrane voltage overshoots its resting membrane potential (near -60mV), the cell enters a phase of hyperpolarization. This is due to a larger-than-resting potassium conductance across the cell membrane. This potassium conductance eventually drops and the cell returns to its resting membrane potential.

The refractory periods are due to the inactivation property of voltage-gated sodium channels and the lag of potassium channels in closing. Voltage-gated sodium channels have two gating mechanisms, the activation mechanism that opens the channel with depolarization and the inactivation mechanism that closes the channel with repolarization. While the channel is in the inactive state, it will not open in response to depolarization. The period when the majority of sodium channels remain in the inactive state is the absolute refractory period. After this period, there are enough voltage-activated sodium channels in the closed (active) state to respond to depolarization. However, voltage-gated potassium channels that opened in response to depolarization do not close as quickly as voltage-gated sodium channels return to the active closed state. During this time, the extra potassium conductance means that the membrane is at a higher threshold and will require a greater stimulus to cause action potentials to fire. This period is the relative refractory period.

See also

• Autowave
• Excitable medium
• Parabolic partial differential equation
• Reaction-diffusion

Notes

References

• Books

• Papers

UpToDate Contents

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English Journal

• Why are sensory axons more vulnerable for ischemia than motor axons?

• Hofmeijer J, Franssen H, van Schelven LJ, van Putten MJ.SourceClinical Neurophysiology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands ; Department of Neurology, Rijnstate Hospital, Arnhem, The Netherlands.
• PloS one.PLoS One.2013 Jun 20;8(6):e67113. doi: 10.1371/journal.pone.0067113. Print 2013.
• OBJECTIVE: In common peripheral neuropathies, sensory symptoms usually prevail over motor symptoms. This predominance of sensory symptoms may result from higher sensitivity of sensory axons to ischemia.METHODS: We measured median nerve compound sensory action potentials (CSAPs), compound muscle acti
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• Left ventricular assist device to avoid heart-lung transplant in an adolescent with dilated cardiomyopathy and severely elevated pulmonary vascular resistance.

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Japanese Journal

• 確率的イオンチャネルが実装された聴神経線維モデルにおける自発性発火レートに依存する共振現象

• カムサ パーリチャット,簑 弘幸
• 電子情報通信学会技術研究報告. MBE, MEとバイオサイバネティックス 111(314), 29-32, 2011-11-17
• 音刺激が与えられていないときでさえも発火する聴神経での活動電位は、自発性スパイク発火とよばれており、それらの生起の時間間隔は指数関数的な確率密度関数で近似され、発火のレート(単位時間あたりのスパイク生起数)で特徴づけられている。本報告では、内有毛細胞シナプスでの神経伝達物質の不規則な分泌に伴う自発性スパイクの発火レートの変化が、確率的イオンチャネルが実装された聴神経有髄線維モデルに正弦波的な音刺激 …
• NAID 110009466116

• 心筋細胞モデルの結合数が拍動リズムに与える影響(グラフ,ペトリネット,ニューラルネット,及び一般)

• 木竜 雄一郎,前田 義信,飯島 敦彦 [他],林 豊彦
• 電子情報通信学会技術研究報告. CAS, 回路とシステム 111(293), 113-118, 2011-11-10
• 長い絶対不応期(プラトー相)を有する活動電位を発生させる心筋細胞は,互いの結合により消費エネルギーが低下すると共に振動数が増加する"高効率加速現象"を起こしうる.本研究では心筋細胞をHodgkin-Huxley型方程式でモデル化したNobleモデル40個を用い,モデルの相互結合数(本研究では2〜12個)が"高効率加速現象"に与える影響についてinsilicoIDEを用いて調べた.その結果,全ての結 …
• NAID 110009465624

• 心筋細胞モデルの結合数が拍動リズムに与える影響(グラフ,ペトリネット,ニューラルネット,及び一般)

• 木竜 雄一郎,前田 義信,飯島 敦彦 [他],林 豊彦
• 電子情報通信学会技術研究報告. MSS, システム数理と応用 111(294), 113-118, 2011-11-10
• 長い絶対不応期(プラトー相)を有する活動電位を発生させる心筋細胞は,互いの結合により消費エネルギーが低下すると共に振動数が増加する"高効率加速現象"を起こしうる.本研究では心筋細胞をHodgkin-Huxley型方程式でモデル化したNobleモデル40個を用い,モデルの相互結合数(本研究では2〜12個)が"高効率加速現象"に与える影響についてinsilicoIDEを用いて調べた.その結果,全ての結 …
• NAID 110009465573

Related Links

• Refractory period (physiology) - Wikipedia, the free encyclopedia

The relative refractory period immediately follows the absolute. As voltage-gated potassium channels open to terminate the action potential by repolarizing the membrane, the potassium conductance of the membrane increases dramatically. ...

Related Pictures

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★リンクテーブル★

リンク元	「有効不応期」「絶対不応期」
関連記事	「refractory」「peri」「absolute」「period」

「有効不応期」

　　[★]

英

effective refractory period, ERP

関

相対不応期

• 絶対不応期と同じような概念。
• The effective refractory period is the shortest interval at which a premature stimulus results in a propagated response and often is used to describe drug effects in intact tissue.(GOO.903)
• This period is also termed the absolute refractory period (ARP). (1)
• 有効不応期は絶対不応期を含むperiodであり、0相から3相の一部を指す(PHD.22)。3相の初期には何らかの刺激により活動電位を発生しうるが、活動電位の伝播は周りに伝わらず局所的なものにとどまる(PHD.22)。すなわち活動電位を発生しない期間に加え、伝播しうる活動電位を発生しない期間を指す。

参考

• 1. wikipedia en

• http://en.wikipedia.org/wiki/Effective_refractory_period

「絶対不応期」

　　[★]

英

absolute refractory period

関

過常期、不応期

「refractory」

　　[★]

• adj.

• 手に負えない、御しがたい
• (病気などが)難治性の、抗療性の。(刺激に)不応性の、無反応性の。抵抗性がある、免疫性の(to)

関

intractable、inveterate、recalcitrance、recalcitrant、refractoriness、resistance、resistant、resistive

　 　 　

「peri」

　　[★]

• pref.

• 近い、周り、周囲の

• ex.

• pericardium 心膜　←　心外膜はepicardium
• perimetrium 子宮外膜
• periosteum 骨膜

関

ambient、around、circumferential、surrounding

　 　

「absolute」

　　[★]

• adj.

• 絶対的な、絶対の、無条件の、(化学)無水の

関

absolutely、anhydrous、categorically、obligate、unconditional、unconditioned

　 　 　 　 　 　 　

「period」

　　[★]

• n.

• 期間、時期

関

duration、phase、stage、term、time