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 [x] voltage gated channels being [y], 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 [x] mV (resting) to [y] mV and back again to the resting membrane potential. This is the result of a change in membrane permeability first to [z] ions then to [a] ions due to the opening of [b] 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 [a] and is [b].

[d] action potentials are recorded at [a] when TTX is applied between R1 and R2 because it [b] propagation of action potentials from [c]

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

Activity 4: TTX blocks diffusion of [x] through [y] [z] channels.