MODULE 2 QUIZ Flashcards
true/false: stimulus strength is encoded by the frequency of APs
true
true/false: hyperpolarization occurs when the membrane potential becomes more positive
false
which statement best describes the AP?
-AP is specialized to transmit signals over only very short distances
-AP is a brief (about 1 ms) change in membrane potential from positive to negative
-AP is an active response that occurs when the cell’s membrane potential reaches threshold
-the level of depolarization is graded in proportion to the magnitude of the stimulus
-AP is initiated by hyperpolarization
AP is an active response that occurs when the cell’s membrane potential reaches threshold
subthreshold current injected into an axon flows ____ along the axon and ____ with distance from the site of injection
-actively, grows
-passively, decays
-passively, remains constant
-actively, decays
-actively, remains constant
passively, decays
which statement about ionic distributions in nerve cells is true?
-postassium is higher outside cells than inside cells
-sodium is higher outside cells than inside cells
-calcium is higher inside cells than outside cells
-the concentrations of all ionic species are the same for all nerve cells in animals
sodium is higher outside cells than inside cells
the resting potential of a cell is negative because
-there is an excess of Na+ outside of the cell at rest
-there is an excess of K+ outside of the cell at rest
-at rest there is an excess of K+ inside the cell, and the membrane is selectively permeable to K+
-at rest there is an excess of Na+ outside of the cell, and the membrane is selectively permeable to Na+
at rest there is an excess of K+ inside the cell, and the membrane is selectively permeable to K+
how does the resting membrane potential of a typical neuron compare to the equilibrium potential (calculated by the Nernst equation) for potassium?
-the resting membrane potential is not exactly equal to the equilibrium potential for potassium because potassium does not contribute to the resting membrane potential
-the resting membrane potential is not exactly equal to the equilibrium potential for potassium because the membrane has some resting permeability to ions other than potassium
-the resting membrane potential is exactly equal to the equilibrium potential for potassium
-the resting membrane potential is not exactly equal to the equilibrium potential for potassium because rapid fluctuations in membrane potential prevent accurate measurements
the resting membrane potential is not exactly equal to the equilibrium potential for potassium because the membrane has some resting permeability to ions other than potassium
studies of the ionic basis of the AP in squid giant axon found that
-decreasing sodium outside the cell increases the size of the AP
-decreasing potassium outside the cell has no effect on the AP
-decreasing sodium outside the cell decreases the size of the AP
-decreasing sodium outside the cell has no effect on the AP
decreasing sodium outside the cell decreases the size of the AP
in a 2-compartment model of a cell with a K+ permeable membrane, at K+ equilibrium potential, there is ____ flux of K+ ions
-a small inward
-a large inward
-a small outward
-no net
-a large outward
no net
how does membrane permeability to K+ (P of K) and Na+ (P of Na) change during an AP?
-P of Na exceeds P of K at rest; P of K temporarily increases during the AP
-P of K exceeds P of Na at rest; P of Na temporarily increases during the AP
-P of Na always exceeds P of K; permeability does not change for either ion
-P of K always exceeds P of Na; permeability does not change for either ion
-P of K exceeds P of Na at rest; P of Na increases during the AP and remains higher than P of K until the next AP, then it quickly drops
P of K exceeds P of Na at rest; P of Na temporarily increases during the AP
