Many phenotypic traits are genetically variable within species, they can readily evolve by natural selection and genetic drift.

TLS Online TPP Program

#Id: 5448

#Unit 7. System Physiology – Animal

During the refractory periods, excitable cells are incapable of producing normal action potentials

TLS Online TPP Program

#Id: 5449

#Unit 7. System Physiology – Animal

Refractory period is divided into:

Absolute refractory period

Relative refractory period

TLS Online TPP Program

#Id: 5450

#Unit 7. System Physiology – Animal

The absolute refractory period overlaps with almost the entire duration of the action potential. During this period, no matter how great the stimulus, another action potential cannot be elicited.

TLS Online TPP Program

#Id: 5451

#Unit 7. System Physiology – Animal

The basis for the absolute refractory period is closure of the inactivation gates of the Na+ channel in response to depolarization. These inactivation gates are in the closed position until the cell is repolarized back to the resting membrane potential.

TLS Online TPP Program

#Id: 5452

#Unit 7. System Physiology – Animal

The relative refractory period begins at the end of the absolute refractory period and overlaps primarily with the period of the hyperpolarizing afterpotential.

TLS Online TPP Program

#Id: 5453

#Unit 7. System Physiology – Animal

During the relative refractory period, stronger than normal stimuli can cause excitation