Exam 1 Quiz Qs 1-3

Question 1

In a voltage clamp, which of the following is measured?

Answer 1

Magnitude and direction of the ionic current

Question 2

How does a voltage clamp work?

Answer 2

It holds the voltage of a neuron constant by injecting current equal to the ionic current passing across the cell membrane.

Question 3

What is the main contributor to the absolute refractory period following the onset of an action potential?

Answer 3

Inactivation of voltage-gated sodium channels

Question 4

Which cells form myelin sheets in the central nervous system?

Answer 4

Oligodendrocytes

Question 5

What is the name of the periodic interruptions of myelin sheets along nerve fibers?

Answer 5

Nodes of Ranvier

Question 6

Which factors make propagation of electrical signals in dendrites more complex than in axons?

Answer 6

Dendrites contain a wide variety of different voltage-gated ion channels

Question 7

What drives primary active transport?

Answer 7

The hydrolysis of ATP

Question 8

What drives secondary active transport?

Answer 8

Ion flux down their electrochemical gradient

Question 9

Why is the sodium–potassium exchange pump said to be electrogenic?

Answer 9

Because it transports unequal numbers of sodium and potassium ions across the membrane

Question 10

How can ion exchange mechanisms be made to run backwards?

Answer 10

By altering one or more of the ion gradient involved in the exchange

Question 11

The neuronal connections in the nervous system can be

Answer 11

convergent, divergent, recurrent, or parallel

Question 12

Which scientist defined the neuron as the single cell unit of the nervous system?

Answer 12

Ramon y Cajal

Question 13

The signal intensity is encoded by which property of the action potential?

Answer 13

Frequency

Question 14

Local graded potentials encode the intensity of a signal by

Answer 14

size of the membrane potential change

Question 15

are arranged with their polar, hydrophilic heads facing outward and their hydrophobic tails extending to the middle of the layer.

Answer 15

Plasma membrane lipid molecules

Question 16

Channel “activation” is a(n)

Answer 16

increase in the frequency of channel opening

Question 17

Hyperpolarization occurs when the membrane potential

Answer 17

becomes more negative

Question 18

Which is true of the potassium equilibrium potential?

Answer 18

It is the membrane potential where electrical forces and concentration gradients are equal and opposite

Question 19

In a model cell at rest, what is the relative concentration of potassium inside the cell?

Answer 19

Higher than the concentration of potassium outside the cell

Question 20

The action of the sodium-potassium exchange pump is electrogenic. What does this mean?

Answer 20

The exchange pump produces an electrical charge.

Question 21

The signal intensity is encoded by which property of the action potential?

Answer 21

Frequency

Question 22

Local graded potentials encode the intensity of a signal by

Answer 22

size of the membrane potential change

Question 23

Channel “activation” is a(n)

Answer 23

increase in the frequency of channel opening

Question 24

In a voltage clamp, which of the following is measured?

Answer 24

Magnitude and direction of the ionic current

Question 25

How does a voltage clamp work?

Answer 25

It holds the voltage of a neuron constant by injecting current equal to the ionic current passing across the cell membrane.

Question 26

The late current observed in voltage clamp experiments contributes to which of these phases of the action potential?

Answer 26

Repolarization

Question 27

Which of the following ions is responsible for the late current following a voltage step in a voltage clamp experiment?

Answer 27

Potassium

Question 28

Which of the following can be attributed to the flow of sodium ions across the membrane?

Answer 28

Early current

Question 29

When Hodgkin and Huxley recorded from a neuron under voltage clamp at +52 mV, which of the following describes what they observed?

Answer 29

No early current and an outward late current

Question 29

When triethanolamine (TEA) is applied to a neuron in a voltage clamp experiment, what results are observed?

Answer 29

An inward early current followed by no late current