Neuroscience-Chapter 2

Question 1

What do electrical signals arise from?

Answer 1

Ion fluxes and non-uniform distribution of ions through the neuron’s semi-permeable membrane

Question 2

Is the resting potential of a membrane negative or positive?

Answer 2

Negative (between -40 and -90 mV)

Question 3

What are receptor potentials?

Answer 3

Activation of sensory neurons by external stimuli

Question 4

What are synaptic potentials?

Answer 4

Electrical signals that travel along axons (“spikes” or “impulses”)

Question 5

What happens when a current makes the membrane potential more negative? (Hyperpolarization)

Answer 5

Nothing

Question 6

What happens when current makes the membrane potential more positive? (Depolarization)

Answer 6

An action potential may or may not occur

Question 7

What is the purpose of an action potential?

Answer 7

Boosts electrical signals of axons so that electrical signals do not degrade over the length of the axon

Question 8

Why do neurons need action potentials?

Answer 8

Because axons are leaky and not good conductors

Question 9

Why are electrical signals generated?

Answer 9

Differences in concentrations of specific ions across nerve cell membranes and selective permeability to these ions

Question 10

How is the ion concentration gradient established?

Answer 10

Active transporters and ion channels

Question 11

What is electrochemical equilibrium?

Answer 11

An exact balance between the concentration gradient that causes K to move from inside to outside and the opposing electrical gradient that tries to stop K from leaving the membrane

Question 12

Is the number of ions that need to flow to produce an action potential significant?

Answer 12

No

Question 13

How can equilibrium potential be predicted?

Answer 13

The Nernst Equation

Question 14

What is the Nernst equation?

Answer 14

E=(58/z)log[x(out)/x(in)]

Question 15

Would the membrane potential be negative or positive if the membrane was more permeable to K than Na?

Answer 15

Negative

Question 16

As K moves outside the cell, does it create a positive or negative membrane potential?

Answer 16

Negative

Question 17

What is the Goldman equation used for?

Answer 17

To determine the voltage across a membrane when it is permeable to more than one ion

Question 18

How does an action potential work?

Answer 18

The resting potential is negative until the membrane potential is depolarized by synaptic action. The permeability to Na increases, making the membrane potential more positive. An action potential occurs. Once the action potential is gone, permeability to K is restored and permeability to Na inactivates and the membrane potential returns to resting level.

Question 19

What did Alan Hodgkin and Bernard Katz do?

Answer 19

Altered the concentration of K in a squid neuron and showed that the membrane of a resting neuron is more permeable to K.

Question 20

Is there a higher concentration of Na on the outside of a neuron or the inside?

Answer 20

Outside

Question 21

What happens during an undershoot?

Answer 21

The membrane potential is hyperpolarized because K permeability, which is even greater than at rest. Hyperpolarization eventually subsides.