The Forces of Evolution

Mutation, 

Genetic drift

Gene flow or migration

Selection

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

TLS Online TPP Program

#Id: 5454

#Unit 7. System Physiology – Animal

The basis for the relative refractory period is the higher K+ conductance than is present at rest. 

TLS Online TPP Program

#Id: 5455

#Unit 7. System Physiology – Animal

The spatial distribution of ion channels along the axon plays a key role in the initiation and regulation of the action potential

TLS Online TPP Program

#Id: 5456

#Unit 7. System Physiology – Animal

Voltage-gated Na+ channels are highly concentrated in the nodes of Ranvier and the initial segment in myelinated neurons.