The relaxation is essential so the heart can fill with blood for the next cycle. The refractory period is very long to prevent the possibility of tetany, a condition in which muscle remains involuntarily contracted. In the heart, tetany is not compatible with life, since it would prevent the heart from pumping blood.
What is the purpose of the refractory period?
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 is the refractory period heart?
The functional refractory period (FRP) is the shortest interval between two consecutively conducted impulses out of a cardiac tissue resulting from any two consecutive input impulses into that tissue (i.e., the shortest output interval that can occur in response to any input interval in a particular tissue).
What is effective refractory period in heart?
In electrocardiography, during a cardiac cycle, once an action potential is initiated, there is a period of time that a new action potential cannot be initiated. This is termed the effective refractory period (ERP) of the tissue.
What causes the long plateau phase of the cardiac muscle action potential?
Another difference between cardiac and nerve and muscle action potentials is the role of calcium ions in depolarization. … In non-pacemaker cells, calcium influx prolongs the duration of the action potential and produces a characteristic plateau phase.
What happens after the refractory period?
The refractory period occurs after the resolution stage. During the refractory period, a male cannot get an erection. This type of response is a physiological refractory period, meaning a person is physically unable to have sex again.
What is the average refractory period?
According to some studies, 18-year-old males have a refractory period of about 15 minutes, while those in their 70s take about 20 hours, with the average for all men being approximately half an hour. Although rarer, some males exhibit no refractory period or a refractory period lasting less than 10 seconds.
What refractory means?
1 : resisting control or authority : stubborn, unmanageable. 2a : resistant to treatment or cure a refractory lesion. b : unresponsive to stimulus.
What does refractory period mean in psychology?
The term psychological refractory period (PRP) refers to the period of time during which the response to a second stimulus is significantly slowed because a first stimulus is still being processed.
What would be the effect on the neuron if there was no refractory period?
An important effect of the refractory period is that it regularizes the spike train: i.e., a neuron having a refractory period but otherwise the same mean ISI as a neuron without refractory period will have a more regular spike train.
What happens during relative refractory period?
During the relative refractory period, a stronger than normal stimulus is needed to elicit neuronal excitation. After the absolute refractory period, Na+ channels begin to recover from inactivation and if strong enough stimuli are given to the neuron, it may respond again by generating action potentials.
How can you improve the effective refractory period?
Sodium-channel blockers (particularly Class IA) also increase the ERP by prolonging the inactivation state of fast-sodium channels. Drugs that increase the ERP can be particularly effective in abolishing reentry currents that lead to tachyarrhythmias.
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.
Why is there a plateau in cardiac action potential?
During phase 1, there is partial repolarization, because of a decrease in sodium permeability. Phase 2 is the plateau phase of the cardiac action potential. Membrane permeability to calcium increases during this phase, maintaining depolarization and prolonging the action potential.
Does cardiac muscle Hyperpolarize?
Abstract. When a bundle of cardiac muscle cells is hyperpolarized, membrane current declines with time. … Following prolonged hyperpolarization, membrane current near the resting potential was generally outward. The half-time of decay of this outward current was approximately 2.5 sec at -60mV.
What happens when the bundle of His is completely interrupted?
effect of pacemaker
…of conductive fibres called the bundle of His, which induces the contraction of the ventricles. When electrical conduction through the atrioventricular node or bundle of His is interrupted, the condition is called heart block.