What is absolute and relative refractory period?

Asked By: Moira Kringler | Last Updated: 30th March, 2020
Category: medical health heart and cardiovascular diseases
4.5/5 (1,039 Views . 13 Votes)
Absolute: Is the period of time during which a second action potential ABSOLUTELY cannot be initiated, no matter how large the applied stimulus is. Relative: Is the interval immediately following the Absolute Refractory Period during which initiation of a second action potential is INHIBITED, but not impossible.

Click to see full answer


Also to know is, what is the relative refractory period?

Medical Definition of relative refractory period : the period shortly after the firing of a nerve fiber when partial repolarization has occurred and a greater than normal stimulus can stimulate a second response — compare absolute refractory period.

Furthermore, what does absolute refractory period mean? The absolute refractory period refers to a period during the action potential. This is the time during which another stimulus given to the neuron (no matter how strong) will not lead to a second action potential.

Beside this, what causes absolute and relative refractory period?

In summary, inactivation of Na+ channels is solely responsible for the absolute refractory period. Both Na+ channel inactivation and greater than resting pK value are responsible for the relative refractory period.

What is absolute refractory period of heart?

Refractory period of cardiac muscle cells . In cardiac muscle cells , There are absolute and relative refractory periods . Absolute refractory period : is a period during which the cardiac excitability is totally cancelled ( cardiac muscle will not respond to any stimulus) .

38 Related Question Answers Found

What happens during a refractory period?

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.

Why is relative refractory period important?

In summary, the relative refractory period is a time in which the neuron can fire an action potential, but it needs a greater stimulus. The refractory period is important because it allows us to adjust briefly to a stimulus and limits the amount of action potentials sent per minute.

What would happen if there was no refractory period?

Refractory period returns the repolarization period to the nerve's resting potential . it's the time taken for recovery of a neuron to generate another impulse being excited by another stimulus . so if nerve doesn't have refractory period they wouldn't be able to return to its resting potential & generate new impulse .

What is the purpose of refractory period?

The Refractory Period. These transitory changes make it harder for the axon to produce subsequent action potentials during this interval, which is called the refractory period. Thus, the refractory period limits the number of action potentials that a given nerve cell can produce per unit time.

How long is the absolute refractory period?


This is the time during which another stimulus given to the neuron (no matter how strong) will not lead to a second action potential. Thus, because Na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials. The absolute refractory period takes about 1-2 ms.

What is the molecular basis of the absolute refractory period?

The absolute refractory period is the time during which another stimulus given to the cell (no matter how strong) will not lead to a second action potential. The molecular basis of the absolute refractory period is described by the ball-and-chain model.

What happens during hyperpolarization?

Hyperpolarization is a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization. It inhibits action potentials by increasing the stimulus required to move the membrane potential to the action potential threshold.

Why does cardiac muscle have long refractory period?

It is important for the cardiac muscle cells to have a longer refractory period because if they were short, the heart could enter tetanic contraction/summation which is when the muscle is stimulated so rapidly that it does not have a chance to relax at all between stimuli.

How would the absolute refractory period be affected?

How would the absolute refractory period be affected if voltage-regulated sodium channels failed to inactivate? It would last indefinitely. It would be much briefer. Muscle tissue and neurons both have refractory periods.

What would most likely lead to an IPSP?


What would most likely lead to an IPSP? A local hyperpolarization that changes a postsynaptic neuron's membrane from resting potential to -85 mV is: an excitatory postsynaptic potential (EPSP).

Why is the resting membrane potential negatively charged?

When the neuronal membrane is at rest, the resting potential is negative due to the accumulation of more sodium ions outside the cell than potassium ions inside the cell.

What does depolarization mean?

In biology, depolarization is a change within a cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell. Depolarization is essential to the function of many cells, communication between cells, and the overall physiology of an organism.

What is the absolute refractory period quizlet?

absolute refractory period (neuron) The interval from the beginning of the action potential until the nerve fiber is able to conduct another action potential; during most of this interval the Na+ and K+ channels remain open. You just studied 6 terms!

What is Saltatory conduction?

Saltatory conduction (from the Latin saltare, to hop or leap) is the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials.

How does the threshold change during the relative refractory period?


This action potential can only occur more frequently if there is a constant source of stimulation after the relative refractory period. Your answer: The threshold changes during the refractory period because it needs a stronger stimulus after the first action potential.

What is the refractory period quizlet?

Refractory Period. The time period from the beginning of the action potential to the return to resting state during which the membrane will not respond normally to additional stimuli. Absolue Refractory Period. Period during which the sodium channels are open or inactivated and no action potential is possible.

What are the two types of refractory periods?

There are two types of refractory periods; the absolute refractory period, which corresponds to depolarization and repolarization, and the relative refractory period, which corresponds to hyperpolarization.