Question

What is Relative refractory period occ?

Answer 1

The term refractory period is usually quoted as the time during which a particular cell or organ cannot repeat a particular function that it is known to perform such as action potential in case of nervous system.

Complete answer:
Refractory period can be divided into two types namely:
i) Absolute refractory period
ii) Relative refractory period

Absolute refractory period
The absolute refractory period is mostly identical and similar in time to the entire action potential in case of neurons. It is caused by the inactivation of the $Na_+$ channels that normally open during the polarization of the nerve membrane. These channels continue to be inactivated unless hyperpolarization usually occurs following which they close and can then respond to another stimulus.

Relative refractory period
The relative refractory period is defined as the one that follows the absolute one. The $K_+$ channels open to depolarize the membrane at the duration of. This period the potassium ions also move out of the membrane due to increased permeability leading to hyperpolarization. This is aided by returning the membrane to its normal resting potential that also gives the sign of the end of the relative refractory period.

Note: Thus, the refractory period can lead to the production of a time lag between two action potentials. Unless the membrane returns back to its original resting state it cannot be excited with another stimulus. Thus, it is helpful in limiting the rate at which action potentials are generated and also plays a role in the unidirectional propagation that is only in one direction of action potential through a particular axon.