Stronger stimuli are able to increase the frequency of action potentials by intruding on the:

What happened to the amount of neurotransmitter release when you switched from the extracellular fluid with no Ca++ to the extracellular fluid with low Ca?

The absolute refractory period is the result of voltage gated channels being , which means that they cannot be opened regardless of stimulus strength.  (refer to the Vander textbook if needed.)

Activity 5:  How does the absolute refractory period ensure directionality of action potential propagation? Include the role of Na+ voltage gated channels.

The action potential changes the membrane potential from mV (resting) to mV and back again to the resting membrane potential. This is the result of a change in membrane permeability first to ions then to ions due to the opening of gated channels.

Why is a long refractory period beneficial for cardiac muscle? Vanders’s Human Physiology textbook is a good source for this question.

Lidocaine differs from TTX in that it and is .

action potentials are recorded at  when TTX is applied between R1 and R2 because it propagation of action potentials from

Hyperpolarized membranes are threshold and require a stimulus that is to generate an action potential.

Activity 4: TTX blocks diffusion of through channels.