BIO110: PHYSIOLOGY FIG 7.1

Which statement best describes the event indicated by the letter “C” in Figure 7.1 and how that event is initiated?

A) It is a subthreshold graded potential resulting from the opening of sodium channels, closure of potassium channels, or opening of ion channels for sodium and potassium.

B) It is a suprathreshold graded potential resulting from the opening and closing of sodium and potassium channels.

C) It is a hyperpolarization of the membrane due to the outward movement of potassium ions.

D) It is a suprathreshold depolarization representing an action potential.

E) It is an excitatory potential that causes the relative refractory period.

A

Which statement best describes the events responsible for the phase represented by the letter “A” in Figure 7.1?

A) The opening of sodium channels
B) The opening and closing of sodium channels
C) The opening of potassium channels
D) The closing of sodium channels and the opening of potassium channels
E) The opening of potassium channels and the closing of sodium channels

A

Which statement best describes the events responsible for the phase represented by the letter “B” in Figure 7.1?

A) The opening of sodium channels
B) The opening and closing of sodium channels
C) The opening of potassium channels
D) The closing of sodium channels and the opening of potassium channels
E) The opening of potassium channels and the closing of sodium channels

A

Identify the type of summation that is occurring in Figure 7.1 where “S” refers to a stimulus from one source measured in the postsynaptic membrane.

A) Multiplier
B) Spatial
C) Subthreshold
D) Suprathreshold
E) Temporal

E

In Figure 7.1, if the direction of event “C” (hyperpolarization) was reversed, how would this affect the ability of the postsynaptic membrane to generate an action potential?

A) Hyperpolarization will reduce the likelihood that an action potential will be generated.
B) Hyperpolarization only causes refractory periods.
C) Hyperpolarization will increase the likelihood that an action potential will be generated.
D) Hyperpolarization will cause an equilibrium potential to be reached between the intracellular fluid and the extracellular fluid.
E) Hyperpolarization only occurs in graded potentials.

A

In Figure 7.1, if S2 indicated a stimulus from a different source and occurred coincident with S1, what type of summation has been generated?

A) Temporal
B) Spatial
C) Subthreshold
D) Suprathreshold
E) Multiplier

B

Movement of what ion is responsible for event “D” in Figure 7.1?

A) Sodium (Na⁺)
B) Potassium (K⁺)
C) Chloride (Cl⁻)
D) Calcium (Ca²⁺)
E) Phosphate (PO₄⁻)

B