Refractory Period of the Heart

Ventricular muscle, unlike skeletal muscle, is incapable of any significant degree of summation of contractions, and this is a very good thing. Imagine that cardiac muscle were able to undergo a prolonged tetanic contraction. During this period, no ventricular filling could occur since filling can occur only when the ventricular muscle is relaxed, and the heart would therefore cease to function as a pump.

The inability of the heart to generate tetanic contractions is the result of the long absolute refractory period of cardiac muscle, defined as the period during and following an action potential when an excitable membrane cannot be re-excited. As described in Chapter 11, the absolute refractory periods of skeletal muscle are much shorter (1 to 2 ms) than the duration of contraction (20 to 100 ms), and a second contraction can therefore be elicited before the first is over (summation of contractions). In contrast, because of the long plateau in the cardiac-muscle action potential, the absolute refractory period of cardiac muscle lasts almost as long as the contraction (250 ms), and the muscle cannot be re-excited in time to produce summation (Figure 14-23).

In this and previous sections, we have presented various similarities and differences between cardiac and skeletal muscle. These were summarized in Table 11-6.

PART THREE Coordinated Body Functions

Vander et al.: Human Physiology: The Mechanism of Body Function, Eighth Edition

PART THREE Coordinated Body Functions

Tension developed

Tension developed

Muscle Contraction Refractory Period

FIGURE 14-23

Relationship between membrane potential changes and contraction in a ventricular muscle cell. The refractory period lasts almost as long as the contraction.

FIGURE 14-23

Relationship between membrane potential changes and contraction in a ventricular muscle cell. The refractory period lasts almost as long as the contraction.

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Responses

  • jasmin
    Why the refractory period a good thing for cardiac muscle?
    7 years ago
  • mezan tesmi
    Why beneficial for refractory period in cardiac muscle?
    7 years ago
  • fabiola
    Why would it be beneficial for cardiac muscle to have a long refractory period?
    7 years ago
  • bilbo
    Why is absolute refractory beneficial for the heart?
    7 years ago
  • renato
    Why would it be beneficial for cardiac muscle to have a long absolute refractory period?
    7 years ago
  • ennio
    What is the significance of the long refractory period to the function of the heart?
    7 years ago
  • Bodo Puddifoot
    Does absolute refractory period in the heart lasts till cardiac contraction?
    7 years ago
  • Freyja
    Why would a second contraction occur in the refractory period of the heart?
    7 years ago
  • yvonne
    Which muscle has a shorter absolute refractory period?
    7 years ago
  • raffaella li fonti
    Which muscle has a long refractory period and what is its contraction?
    7 years ago
  • GARRY
    What is absolute refractory period skeletal muscle?
    7 years ago
  • ALFRED STEVENSON
    What different functions result from from different absolute refractory period in muscles?
    7 years ago
  • zahra
    When we can program post ventricular refractory period?
    6 years ago
  • John
    What is significant of a long refractory period of the heart?
    6 years ago
  • Dora
    Why long refractory period is functional in cardiac muscle?
    6 years ago
  • gene
    Why does skeletal muscle have short refractory period?
    6 years ago
  • Sanna-Leen Kulmala
    What is The total refractory period of cardiac muscle?
    6 years ago
  • Hagosa
    Why do cardiac cells have a long refractory period?
    6 years ago
  • LIISI
    Why is the refractory period of cardiac muscle is much longer than that of skeletal muscle?
    6 years ago
  • linda
    Why do cardiac fibers have a long refractory period?
    6 years ago
  • Ali
    Does skeletal muscle or cardiac have a shorter refractory period?
    6 years ago
  • ralf
    Does skeletal or heart muscle have a shorter refractory period?
    6 years ago
  • pupa
    What is functional ventricular refractory?
    6 years ago
  • Paul
    Which muscle has the longest refractory period?
    6 years ago
  • peter brown
    Why does the skeletal muscle have a shorter refactory?
    6 years ago
  • florian
    Why is a long refractory period necessary in cardiac muscle cells?
    6 years ago
  • irene
    Why do cardiac muscle cell have a long refractory period?
    6 years ago
  • agostino
    Why is refractory longer in the heart?
    5 years ago
  • Learco
    Does a refractory period of cardiac muscle lasts as long as a contraction period?
    5 years ago
  • annett friedmann
    Why is the refractory period longer in the heart?
    5 years ago
  • selam
    Why is it necessary for the refractory phase of a cardiac muscle to be longer than a skeletal muscle?
    5 years ago
  • venera
    What is the sigificance of refractory period in heart function?
    5 years ago
  • andrea
    How does a long refractory period happen in the heart?
    5 years ago
  • shawn
    Why cardaic muscles have long refractory period?
    3 years ago
  • jonah
    WHY IS CARDIAC MUSCLEIS LONGER THAN SKELETAL MUSCLES DURING REFACTORY PERIOD?
    2 years ago
  • Semere
    Why long refractory venticular?
    2 years ago
  • Annika
    When absolute refractory period is longest?
    2 years ago
  • Genet Kifle
    Why refractory period is longer in cardiac muscles?
    2 years ago
  • bradley
    Which cells have the longest refractory period?
    2 years ago
  • Venanzio
    Which cardiac cell has the longest refractory period?
    2 years ago
  • AINO
    What are the importance of refractory period of cardiac muscle?
    2 years ago
  • hagos
    What means refractory of cardiac muscle?
    2 years ago
  • Nazario
    What is a normal refractory period for a heart?
    2 years ago
  • Alex
    Why is the heart incapable of any degree of summation of the contractions?
    2 years ago
  • samsa
    What is the refractory period in human heart?
    2 years ago
  • gimja
    Why is a longer refractory period desired?
    2 years ago
  • posco
    What is the importance of the refractory periods of the heart?
    2 years ago
  • noemi
    Which muscle have longer duration of refractory period?
    2 years ago
  • Grimalda
    Why does myocardium has long refractory period and its importance?
    2 years ago
  • saradoc
    What is the importance of prolong refrac?
    2 years ago
  • johnnie
    Why is refractory period important in normal cardiac function?
    1 year ago
  • eyob tewelde
    Why refractory period of cardiac muscle is prolonged?
    1 year ago
  • Helen Lang
    What is the cause of the long refractory period of a heart muscle?
    1 year ago
  • robert
    What is the cause of the long refractory period of the heart muscle of the toad heart?
    1 year ago
  • Barbara
    Why avoid heart refratory period?
    1 year ago
  • seren
    What is the meaning of heart period in the body?
    1 year ago
  • iivari
    How long does refractory period in skeletal muscle last?
    1 year ago
  • jeremy
    Why is the refractory period of atrial muscle shorter than ventricle?
    1 year ago
  • amanuel
    Why refractive period of cardiacmuscles is high?
    1 year ago
  • joseph
    Why do cardiac muscles have a short period of contraction?
    1 year ago
  • rosa sackville
    Does smooth musle have short or long refractory period?
    1 year ago
  • Cora
    Why hesart have long refrectory peroid?
    1 year ago
  • jennifer
    What is reason of long refrectory period of heart muscle ?
    12 months ago
  • alesha
    Why does cardiac muscle have a longe refractory period?
    11 months ago
  • ann
    What is absolutely necessary for heart function?
    11 months ago
  • almaz
    What is a relative refractory period and why do muscles have them?
    11 months ago
  • katja
    Why refrectory period is long in cardian mucles?
    11 months ago
  • Ilkka
    Why cardiac muscle have high refractory periode?
    10 months ago
  • eino p
    Why relative refractory period muscle is longer?
    10 months ago
  • Declan
    What special of refractory period of cardiac muscles?
    10 months ago
  • Charley
    Why cardiac muscle does not get tired due to plateau phase?
    9 months ago
  • tom
    Why don't cardiac muscles get tired due to plateau phase?
    9 months ago
  • Marko
    How long is a typical venticular muscle cell?
    9 months ago
  • sago chubb-baggins
    Is the plateau in cardiac muscle is part of absolute refractory period?
    8 months ago
  • MYLES
    Why refractory period of atria is small than ventricle?
    8 months ago
  • nina
    Does cardiac muscle have tetanic contraction?
    8 months ago
  • Robert
    Do the heart muscle action potential summate?
    8 months ago
  • angelica
    How much refectory period in human heart?
    7 months ago
  • asphodel
    What happens tothe heart if it undergo etanuc?
    7 months ago
  • Reece Smith
    What prevents the heart from undergoing summation?
    6 months ago
  • ensio kolkkala
    What is a refractory peiod for a cardiac cell?
    6 months ago
  • Gerda
    Do cardiac cells have a longer refractory period?
    6 months ago
  • Virpi
    What is relatively refractory and absolute refractory differ in the skeletal and cardiac muscle?
    6 months ago
  • ANTHONY
    Why do cardiac mucles have long absolute refractory periods?
    6 months ago
  • ben
    How does absolute refractory and relative refractory period differ in skeletal and cardiac muscle?
    6 months ago
  • safa
    How does skeletal muscle refractory period end before peak tension is reached?
    6 months ago
  • MARIA
    Why does the cardiacs long refractory period prevents summation?
    6 months ago
  • monika
    How refractory period differs in cardiac muscle and skeletal muscle?
    6 months ago
  • tuomo
    Which heart cells have a refractory period in their action potential?
    4 months ago
  • abel
    How long is a typical ventricular muscle cell?
    4 months ago
  • geoffrey woolf
    Why cardiac muscles have high refractory period?
    2 months ago
  • ALESHA WOOD
    Do cardiac muscles summate?
    2 months ago
  • monika
    Why does the heart musce have a long refractory period?
    9 days ago
  • onni
    Why does the heart have long absolute refractory period?
    8 days ago

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