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.
What is the difference between absolute refractory and relative refractory?
Absolute and relative refractory periods. During the absolute refractory period, a second stimulus (no matter how strong) will not excite the neuron. During the relative refractory period,
a stronger than normal stimulus is needed to elicit
neuronal excitation.
What is the relative refractory period?
The relative refractory period is
the interval of time during which a second action potential can be initiated
, but initiation will require a greater stimulus than before. Refractory periods are caused by the inactivation gate of the Na
+
channel.
What happens in the absolute refractory period?
The cell membrane cannot immediately produce a second AP. The period of time when the majority of voltage-gated Na
+
channels are inactivated defines the ABSOLUTE REFRACTORY PERIOD, when
no amount of depolarizing current can cause an action potential
.
What causes the absolute and relative refractory periods?
Explanation: Absolute refractory period occurs because of the inactivation of sodium channels. Since the sodium channels are inactivated, the neuron can’t depolarize and initiate another action potential. Relative refractory period occurs due to
the slow inactivation of potassium channels
.
What is the benefit of a relative refractory period?
Why is the Relative Refractory Period Important For Our Bodies? The relative refractory period
prevents the same stimulus from becoming overwhelming
. Since it takes a greater stimulus to produce an action potential, the body needs more sensory input to continue feeling the same way.
What are the benefits of a refractory period?
It is initiated by paced or sensed events; after a sensed event, the refractory period
prevents double counting the same event
, whereas after a paced event, it prevents sensing the pacing stimulus, its after-potential, or the evoked response. Events within the refractory period do not reset the LRI.
Why do we use the absolute refractory period?
The absolute refractory period is a period where it is completely impossible for another action potential to be activated, regardless of the size of the trigger (stimulus). This is because
the sodium channels are inactivated and remain that way until hyperpolarisation occurs
.
How long is the absolute refractory period?
The absolute refractory period is the brief interval after a successful stimulus when no second shock, however maximal, can elicit another response. Its duration in mammalian A fibres is
about 0.4 ms
; in frog nerve at 15
o
C it is about 2 ms.
What is the refractory stage?
The refractory period occurs
right after you reach your sexual climax
. It refers to the time between an orgasm and when you feel ready to be sexually aroused again. It’s also called the “resolution” stage.
Which channel gets open up after a stimulus is applied?
The opening of
sodium channels
allows nearby sodium channels to open, allowing the change in permeability to spread from the dendrites to the cell body.
What is ERP 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 is an example of a refractory period?
An example of the refractory period is
when talking on the phone while driving causes you to react slower to seeing a stopped car in front of you
. So the next time you see a friend texting and driving, remind them that by doing so they are slowing their reaction time, which could be dangerous.
What are the two types of graded potentials?
Graded potentials can be of two sorts, either they are
depolarizing or hyperpolarizing
(Figure 1).
How does the threshold change during relative refractory period?
How does the threshold change during the relative refractory period?
The threshold that must be achieved is higher than the original stimulus intensity during the relative refractory period
.
What happens after the refractory period?
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
.
