Deck 4: Extension: A - the Structure and Electrical Activity of Neurons

Question 1

The information - processing units of the nervous system are:

A) glial cells.
B) ependymal cells.
C) neurons.
D) nuclei.

Answer 1

neurons.

Question 2

Under resting conditions, the opening of Na⁺ channels results in a(n) _____ of Na⁺ ions.

A) efflux
B) influx
C) reflux
D) discharge

Answer 2

influx

Question 3

Which of the following ions is LEAST likely to pass through the cell membrane when the neuron is at rest?

A) organic anions
B) sodium cations
C) potassium cations
D) chloride anions

Answer 3

organic anions

Question 4

Depolarization is usually due to the movement of _____.

A) K⁺
B) Cl^-
C) Na⁺
D) An^-

Question 5

Exocytosis is the process by which:

A) old neural cells are replaced with newly generated neurons.
B) cellular constituents are transferred from dendrites to axons of neurons.
C) proteins are taken up by neural cells from the extracellular environment.
D) proteins are released by cells into the extracellular environment.

Question 6

In order for a neuron to reach the threshold for generating an action potential, it must be:

A) hyperpolarized.
B) unipolarized.
C) depolarized.
D) inhibited.

Question 7

The basic structure of the cell membrane of a neuron consists of a double layer of phospholipid molecules in which are embedded _____.

A) proteins
B) neurotransmitters
C) chromosomes
D) ions

Question 8

A brief but large reversal in the membrane potential is characteristic of:

A) the resting membrane potential.
B) graded excitatory potentials.
C) the action potential.
D) a voltage gradient.

Question 9

It is currently held that humans have about _____ active genes.

A) 20,000-25,000
B) 8000-9000
C) 100,000-200,000
D) 2000-3000

Question 10

Electrical excitability in neurons is maintained by a molecular pump which exchanges _____ across the plasma membrane.

A) Na⁺ and Cl^-
B) K⁺ and A^-
C) K⁺ and Cl^-
D) Na⁺ and K⁺

Question 11

Neurotransmitters are chemicals responsible for:

A) propagating the nerve impulse.
B) transmitting signals between neurons.
C) transmitting signals within neurons.
D) providing energy to power cellular processes.

Question 12

The chemical energy used to power a neuron's activities is synthesized by the:

A) Golgi apparatus.
B) nucleus.
C) mitochondria.
D) synaptic vesicles.

Question 13

The main ion responsible for the restoration of the resting potential is _____.

A) sodium
B) calcium
C) potassium
D) magnesium

Question 14

The small protrusions found on the dendrites of neurons are called:

A) spines.
B) thorns.
C) terminal buttons.
D) receptors.

Question 15

The process by which molecules move from areas of high concentration to areas of low concentration is called:

A) diffusion.
B) osmosis.
C) gating.
D) exocytosis.

Question 16

A change in the membrane potential from -65 mV to -70 mV is an example of:

A) hyperpolarization.
B) depolarization.
C) an action potential.
D) saltatory conduction.

Question 17

Newly synthesized proteins are integrated into a membrane and "addressed" by the:

A) Nissl substance.
B) Golgi apparatus.
C) lipofuscin granules.
D) mitochondria.

Question 18

The main ion responsible for initiating the action potential at the axon hillock is _____.

A) potassium
B) sodium
C) chlorine
D) calcium

Question 19

A characteristic resting potential in a neuron would be about _____ mV.

A) -30
B) 0
C) -70
D) 50

Question 20

The biochemical process by which the information encoded in RNA is used to make proteins is:

A) translation.
B) transcription.
C) transduction.
D) transliteration.

Question 21

The movement of which of the following ions is MOST likely to produce a hyperpolarization following an action potential?

A) potassium
B) calcium
C) sodium
D) organic anion

Question 22

The Na⁺ channel - blocking poison found in puffer fish is:

A) tetraethylammonium.
B) tetrodotoxin.
C) curare.
D) ouabain.

Question 23

A long, myelinated axon lacking nodes of Ranvier would probably:

A) propagate nerve impulses faster than one with nodes of Ranvier.
B) propagate impulses at the same rate as one with nodes of Ranvier.
C) not propagate nerve impulses more slowly than one with nodes of Ranvier.
D) propagate nerve impulses backward.

Question 24

Tetrodotoxin most specifically interferes with which component of neural transmission?

A) neurotransmitter release
B) neurotransmitter synthesis
C) action potential propagation
D) protein synthesis

Question 25

Nerve impulses in mammals can travel at speeds up to about _____ meters per second.

A) 10
B) 1000
C) 30
D) 120

Question 26

During _____ a neuron is incapable of generating an action potential.

A) saltatory conduction
B) neurotransmitter release
C) the absolute refractory period
D) the relative refractory period

Question 27

Multiple sclerosis results from the deterioration of _____.

A) Na⁺ channels
B) myelin
C) axon hillock
D) the blood-brain barrier

Question 28

The closer a synapse is to the _____, the more influential it is going to be in determining the production of action potentials in that neuron.

A) dendrites
B) teleodendria
C) nodes of Ranvier
D) axon hillock
Answer Key

Question 29

Multiple sclerosis is a neurodegenerative disorder in which:

A) myelin is damaged.
B) dendrites lose their spines.
C) neurotransmitter synthesis is blocked.
D) there is excess electrical activity.

Question 30

The two factors that determine nerve impulse speed in the axon are:

A) axon diameter and myelination.
B) axon length and myelination.
C) nodes of Ranvier and myelination.
D) axon diameter and the availability of Na⁺ ions.

Question 31

Saltatory conduction occurs in neurons with _____.

A) synaptic connections
B) voltage differentials
C) organic ions
D) myelin sheaths

Question 32

The movement of the action potential from axon hillock to axon terminal is known as:

A) the graded potential.
B) the refractory period.
C) the nerve impulse.
D) anterograde transport.