Permian - Major mass extinctions, amphibians decline

TLS Online TPP Program

#Id: 5445

#Unit 7. System Physiology – Animal

Sodium channels can be blocked by a toxin called tetrodotoxin when it is applied to the outside of the cell membrane (activation gates)

TLS Online TPP Program

#Id: 5446

#Unit 7. System Physiology – Animal

Tetraethylammonium ion blocks the potassium channels when it is applied to the interior of the nerve fiber.

TLS Online TPP Program

#Id: 5447

#Unit 7. System Physiology – Animal

All-or-none action potentials

the minimal intensity of stimulating current (threshold intensity) that, acting for a given duration, will just produce an action potential. The thresholdintensity varies with the duration; with weak stimuli it is long, and with strong stimuli it is short

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.