Deck 45: Neurons and Nervous Systems

Question 1

Which statement accurately describes an action potential?

A) Its magnitude increases along the axon.
B) Its magnitude decreases along the axon.
C) All action potentials in a single neuron are of the same magnitude.
D) During an action potential, the membrane potential of a neuron remains constant.
E) An action potential permanently shifts a neuron's membrane potential away from its resting value.

Answer 1

C

Question 2

What is the difference between a nerve and a neuron?

A) A nerve includes parts of multiple neurons.
B) A neuron is only the soma, or body, of a nerve.
C) Nerves carry information away from the brain, whereas neurons carry information to the brain.
D) Nerves are cells that nourish and support the neurons.
E) None of the above; there is no difference between these terms.

Answer 2

A

Question 3

The difference between slow and fast synapses is

A) the width of the synaptic cleft.
B) the size of the synapse.
C) whether or not the neurotransmitter acts directly on ion channels.
D) the density of receptors on the postsynaptic membrane.
E) the amount of neurotransmitter that is released.

Answer 3

C

Question 4

The rising phase of an action potential is due to the

A) closing of K⁺ channels.
B) opening of chemically gated Na⁺ channels.
C) closing of voltage-gated Ca²⁺ channels.
D) opening of voltage-gated Na⁺ channels.
E) spread of positive current along the plasma membrane.

Question 5

Graded membrane potentials

A) can be more negative than resting potential.
B) can be less negative than resting potentials.
C) integrate the many synaptic inputs to a cell.
D) are important means of summing sensory inputs.
E) are all of the above.

Question 6

Some organisms, such as earthworms and squid, have clusters of neurons called

A) the spinal cord.
B) the central nervous system.
C) the peripheral nervous system.
D) ganglia.
E) None of the above

Question 7

Whether a synapse is excitatory or inhibitory depends on the

A) type of neurotransmitter.
B) presynaptic axon terminal.
C) size of the synapse.
D) nature of the postsynaptic receptors.
E) concentration of neurotransmitter in the synaptic space.

Question 8

The two primary cell types of the nervous system are _______ and _______.

A) fibroblasts; chondrocytes
B) neurons; glial cells
C) epithelial cells; glandular cells
D) neurons; epithelial cells
E) neuromuscular cells; epithelial cells

Question 9

The binding of an inhibitory neurotransmitter to the postsynaptic receptors results in

A) depolarization of the membrane.
B) generation of an action potential.
C) hyperpolarization of the membrane.
D) increased permeability of the membrane to sodium ions.
E) increased permeability of the membrane to calcium ions.

Question 10

The fear response that is triggered by a potentially dangerous situation results from activation of the

A) geniculate nucleus.
B) hippocampus.
C) amygdala.
D) frontal lobe.
E) cortex.

Question 11

Which of the following behaviors might result from an injury to the amygdala?

A) Walking in the middle of a busy highway
B) Perceiving the color red as blue
C) Misinterpreting the sound of a siren as music
D) Mistaking a person for a hat
E) Sleeping incessantly

Question 12

Which statement about synaptic transmission is not true?

A) The synapses between neurons and skeletal muscle cells use ACh as their neurotransmitter.
B) A single vesicle of neurotransmitter can cause a muscle cell to contract.
C) The release of neurotransmitter at the neuromuscular junction causes the motor end plate to depolarize.
D) In vertebrates, the synapses between motor neurons and muscle fibers are always excitatory.
E) Inhibitory synapses cause the resting potential of the postsynaptic membrane to become more negative.

Question 13

When you decide to mark a particular answer to this question, and your nervous system sends the comm­and to your hand to do so, the command is carried by

A) afferent neurons.
B) efferent neurons.
C) nodes.
D) glial cells.
E) None of the above

Question 14

The resting potential of a neuron is due mostly to

A) local current spread.
B) open Na⁺ channels.
C) synaptic summation.
D) open K⁺ channels.
E) open Cl^- channels.

Question 15

What is the difference between glia and neurons?

A) Glia include parts of multiple neurons.
B) A neuron is only the soma, or body, of a glial cell.
C) Glia carry information away from the brain, whereas neurons carry information to the brain.
D) Glia are cells that nourish and support the neurons.
E) None of the above; there is no difference between these terms.

Question 16

A neuron that has just fired an action potential cannot be immediately restimulated to fire a second action potential. The short interval of time during which restimulation is not possible is called

A) hyperpolarization.
B) the resting potential.
C) depolarization.
D) repolarization.
E) the refractory period.

Question 17

Which of the following is not one of the functions of glial cells?

A) Supporting neurons during embryonic development
B) Supplying nutrients
C) Conducting nerve impulses
D) Consuming foreign particles
E) Insulating nerve tissue

Question 18

When you read this question and your nervous system sends the information from your eyes to your brain, the information is carried by

A) afferent neurons.
B) efferent neurons.
C) nodes.
D) glial cells.
E) None of the above

Question 19

The brain center called the amygdala is responsible for

A) coordinating information between both hemispheres of the brain.
B) the emotion and memory of fear.
C) night vision.
D) interpretation of music.
E) long-term memory

Question 20

Which of the following is a likely mechanism for long-term potentiation?

A) When glutamate binds to postsynaptic AMPA receptors, it activates intracellular changes.
B) When glutamate binds to NMDA receptors, it allows magnesium ions to enter the cell, which initiate intracellular changes.
C) When sufficient glutamate is released by the presynaptic neuron, it dislodges Mg²⁺ from the AMPA receptors and allows Ca²⁺ to leave the cell.
D) When sufficient glutamate is released, both AMPA and NMDA receptors are activated, and NMDA receptors allow Ca²⁺ as well as Na⁺ to enter the cell, thus initiating intracellular changes.
E) When both glutamate and ACh are released together, they create a long-lasting depolarization of the postsynaptic cell.

Question 21

Neurons that transmit information from sensory cells to the central nervous system are part of the

A) brain.
B) peripheral nervous system.
C) central nervous system.
D) spinal cord.
E) nerve net.

Question 22

Which of the following brain areas integrates sensory and motor information?

A) Brain stem
B) Olfactory lobe
C) Cerebrum
D) Cerebellum
E) None of the above

Question 23

Many parts of the nervous system are glistening white in appearance because

A) of the actions of astrocytes.
B) they are coated in a matrix similar to that of bone.
C) they are coated with myelin.
D) they co-occur with fatty adipose tissue.
E) None of the above

Question 24

At the anterior ends of animals, some ganglia become enlarged or even fuse together

A) in a continuous process as the animals get older.
B) as one moves from simple to more complex animals.
C) at sexual maturity.
D) in animals showing radial symmetry.
E) when glial cells are damaged.

Question 25

Which of the following differs the least among species?

A) Brainstem
B) Olfactory lobe
C) Cerebrum
D) Cerebellum
E) These all vary equally among species.

Question 26

The myelin sheath that surrounds some axons in the peripheral nervous system is formed by

A) neurons.
B) Schwann cells.
C) bacteria that have invaded the nervous system.
D) synapses.
E) None of the above

Question 27

The area where two neurons come into close contact with each other and pass along information

A) is nearly always in a ganglion.
B) differs with different types of neurons.
C) is called a synapse.
D) is at the node of Ranvier.
E) is located in the middle of the neurons.

Question 28

Ganglia frequently come in pairs

A) with one ganglion at each end of an animal.
B) with one ganglion controlling afferent neurons and the other controlling efferent neurons.
C) in animals that show bilateral symmetry.
D) with one ganglion controlling sensory neurons and the other controlling effectors.
E) None of the above

Question 29

When you touch a hot stove a nerve impulse travels up your arm, passes briefly through your central nervous system, and a response is sent down your arm to move your hand. The system described here

A) would also rely on an effector.
B) has evolved only in humans.
C) constitutes a neural network.
D) does not involve the peripheral nervous system.
E) Both a and c

Question 30

Neurons

A) have a uniform shape throughout the nervous system.
B) are more numerous than glial cells in the nervous system.
C) are found in mammals and birds only.
D) communicate with other cells at synapses.
E) All of the above

Question 31

While you read this question, your neurons are busy sending information to and from your brain; meanwhile, the metabolic needs of those neurons are met by

A) afferent neurons.
B) efferent neurons.
C) interneurons.
D) glial cells.
E) None of the above

Question 32

Which of the following is not a type of glial cell?

A) Oligodendrocytes
B) Neural crest cells
C) Astrocytes
D) Microglial cells
E) Schwann cells

Question 33

Most synapses

A) in vertebrates are chemical synapses.
B) cover a space about 25 nanometers wide.
C) are crossed by neurotransmitters.
D) are about 1/2000^th the width of a human hair.
E) All of the above

Question 34

The blood-brain barrier protects the brain

A) mostly during fetal development.
B) from toxic chemicals.
C) by maintaining a blood supply for the brain that is separate from the rest of the body.
D) through the action of microglial cells that reduce the permeability of small blood vessels.
E) Both b and d

Question 35

Which of the following structures is not a part of most neurons?

A) Nodes
B) Cell body
C) Axon terminal
D) Dendrite
E) Axon

Question 36

The human capacity to learn, process information, carry out complex tasks, and experience emotions

A) diminishes with age.
B) is due to the human brain's lack of synapses, which allows for increased speed of signal transmission.
C) is due to the weakness of the human sensory system, relative to other animals, which allows the human brain to focus on higher cognitive functions and emotional responses.
D) is due to the capacity of synapses to change their number and size and become more or less sensitive.
E) None of the above

Question 37

Which of the following statements about the nervous system is false?

A) It is the most complex system of the human body.
B) Oligodendrocytes cover the axons of neurons in the peripheral nervous system.
C) Effectors are muscles or glands.
D) Sensory cells transduce information into electric signals that can be transmitted by neurons.
E) Thousands of synapses impinge on most neurons.

Question 38

When you read this question and eventually mark an answer, your neurons busily send information to and from your brain, and compare it against what you learned in class. Coordination of these processes is supplied by

A) afferent neurons.
B) efferent neurons.
C) interneurons.
D) glial cells.
E) None of the above

Question 39

There are about _______ neurons in the human brain.

A) 100,000
B) 1 million
C) 100 million
D) 1 billion
E) 100 billion

Question 40

Anesthetics and alcohol can permeate the blood-brain barrier because

A) they are small molecules.
B) they are water-soluble.
C) they are fat-soluble.
D) they pass through gated channels.
E) there are receptors for them on blood vessels.

Question 41

The sodium-potassium pump

A) needs energy to work.
B) moves potassium ions to the inside of a neuron and sodium ions to the outside.
C) works against a concentration gradient.
D) All of the above
E) None of the above

Question 42

The resting potential across the neuronal membrane is generally maintained by the

A) sodium-potassium pump.
B) action potential.
C) resting potential.
D) voltage-gated channels.
E) negative ion pump.

Question 43

Nerves _______ have the most rapid action potentials.

A) with the thinnest axon diameters
B) with myelin sheaths
C) of invertebrate animals
D) with the greatest membrane potential
E) with the most ion channels

Question 44

Which of the following describes the resting potential of the neuronal cell membrane?

A) The inside is 60 millivolts more positive than the outside.
B) The outside is 60 millivolts more positive than the inside.
C) The inside is 30 millivolts more positive than the outside.
D) The outside is 30 millivolts more positive than the inside.
E) The inside has about the same charge as the outside.

Question 45

The action potential

A) travels along all axons at the same speed.
B) is slowed down in myelinated nerve cells.
C) is blocked at the nodes of Ranvier.
D) causes a brief depolarization of the membrane potential.
E) triggers a simultaneous change in potential along the entire axon.

Question 46

When an action potential arrives at an axon terminal, it causes the opening of _______ channels, which triggers fusion of neurotransmitter vesicles with the cell membrane.

A) calcium
B) sodium
C) potassium
D) chloride
E) acetylcholine

Question 47

Which of the following statements about voltage-gated channel proteins is true?

A) If the membrane voltage reaches threshold potential, ions are pumped through the membrane.
B) If the membrane voltage reaches threshold potential, ions can diffuse through the membrane.
C) Ions can move through the membrane only if the overall membrane voltage stays the same.
D) Ions are pumped through the membrane in order to maintain existing membrane voltage.
E) When the gates close, membrane voltage does not change.

Question 48

Action potentials

A) are initiated by the membrane's increased permeability to potassium.
B) return to resting when the sodium channels open.
C) can be triggered in very rapid succession, with no delay.
D) involve voltage-gated channels in the membrane.
E) are propagated only because chloride ions move through the membrane.

Question 49

Saltatory conduction results when

A) continuous propagation of the nerve impulse speeds up.
B) a nerve impulse jumps from one neuron to another.
C) the threshold for an action potential is suddenly increased.
D) action potentials spread from node to node down the axon.
E) the direction of an action potential suddenly changes.

Question 50

The frequency at which a single neuron can "fire" action potentials is limited by the

A) number of synapses that the neuron forms.
B) number of other cells that the neuron contacts.
C) refractory period for the neuron's Na⁺ channel.
D) length of the axon of the neuron.
E) number of dendrites on the neuron.

Question 51

Which of the following can carry electric charges across the cell membrane?

A) Electrons
B) Protons
C) Water
D) Ions
E) Proteins

Question 52

Action potentials are also called

A) potential energy.
B) resting potentials.
C) nerve impulses.
D) neural potentials.
E) leak currents.

Question 53

The sodium-potassium pump is a(n) _______ membrane protein.

A) uniport
B) antiport
C) symport
D) biport
E) ionoport

Question 54

Which of the following ions is most responsible for generating an action potential?

A) Na⁺
B) K⁺
C) Cl^-
D) H⁺
E) OH^-

Question 55

Patch clamping

A) fixes a break in a cell membrane.
B) records electrical activity inside a cell.
C) records ion movements through a single channel.
D) records ion movements through the entire neuron.
E) records an action potential through a single channel.

Question 56

Voltage is to the flow of electrically charged particles as

A) pressure is to the flow of water.
B) width is to a pond.
C) altitude is to air particles.
D) primary structure is to an amino acid.
E) None of the above

Question 57

If Na⁺ channels open and sodium ions diffuse into the cell,

A) the cell will become hyperpolarized.
B) other sodium ions will move out of the cell.
C) voltage-gated channels will remain closed.
D) the charge across the nearby membrane will change.
E) action potentials will be triggered.

Question 58

Hodgkin and Huxley's studies of the electrical properties of axonal membranes were performed on the very large neurons of

A) the African elephant.
B) the blue whale.
C) redwood trees.
D) squids.
E) the short-tailed shrew.

Question 59

Following depolarization, the neural membrane potential is restored in some neurons when

A) Na⁺ ions rush outward through the membrane.
B) K⁺ ions rush outward through the membrane.
C) Cl^- ions rush inward through the membrane.
D) a pump moves ions to their original concentrations.
E) the membrane becomes freely permeable to many ions.

Question 60

The resting potential of a neuron is produced by

A) voltage-gated channels in the membrane.
B) chemically gated channels in the membrane.
C) potassium channels in the membrane that are permanently open.
D) the concentration difference in Na⁺ across the membrane.
E) blockage of the sodium-potassium pump.

Question 61

Which of the following statements about acetylcholine is false?

A) Acetylcholine is a neurotransmitter.
B) Acetylcholine is found at mammalian neuromuscular junctions.
C) Both smooth muscles and skeletal muscles respond to acetylcholine.
D) Acetylcholine is degraded by acetylcholinesterase.
E) Acetylcholine increases contractility of the heart.

Question 62

Narcotic drugs such as opium activate _______ receptors.

A) GABA
B) endorphin
C) enkephalin
D) Both b and c
E) All of the above

Question 63

Long-term potentiation

A) was discovered by neurobiologists working with brain slice preparations.
B) involves an enhanced postsynaptic response.
C) results from repeated stimulation of a presynaptic cell.
D) involves activation of the NMDA receptor.
E) All of the above

Question 64

When an action potential arrives at the axon terminal, the voltage-gated calcium channels at the terminal

A) release calcium into the synaptic cleft.
B) actively transport neurotransmitter into the synaptic cleft.
C) open; the influx of calcium causes the vesicles to fuse with the presynaptic membrane and release a neurotransmitter into the synaptic cleft.
D) depolarize the membrane at the axon terminal.
E) cause the membrane receptors to bind the neurotransmitter.

Question 65

When the neurotransmitter diffuses across the synaptic cleft,

A) it automatically causes depolarization of the post­synaptic membrane.
B) it can be excitatory or inhibitory, depending on the type of postsynaptic membrane.
C) a single molecule is sufficient to trigger activation of the postsynaptic membrane.
D) only a few molecules make it to the postsynaptic membrane.
E) it must move through nodes in the myelin sheath.

Question 66

Electrical synapses

A) do not integrate information well.
B) contain gap junctions.
C) cannot be inhibitory.
D) are a rapid means of signal transmission.
E) All of the above

Question 67

Most nerve cells communicate with others by means of

A) electric signals that pass across synapses.
B) chemical signals that pass across synapses.
C) bursts of pressure that "bump" the postsynaptic cell membrane.
D) Na⁺ ions as they are released from one cell and enter the next.
E) None of the above

Question 68

Which of the following statements about dopamine is true?

A) It is a derivative of tyrosine.
B) It is a neurotransmitter of the central nervous system.
C) It is a monoamine.
D) All of the above
E) None of the above

Question 69

Which of the following neurotransmitters is used by neurons as an intercellular messenger?

A) Glycine
B) Norepinephrine
C) Nitric oxide
D) Adenosine
E) None of the above

Question 70

The most critical area in a neuron for "decision making" is the

A) axon hillock.
B) presynaptic terminal.
C) postsynaptic terminal.
D) cell body.
E) synapse.

Question 71

Muscarinic receptors of acetylcholine

A) are found in heart muscle.
B) tend to be inhibitory.
C) are an example of a metabotropic receptor.
D) Both a and b
E) All of the above

Question 72

Neurons communicate with each other at electrical synapses by means of

A) a myelin sheath.
B) ionotropic receptors.
C) metabotropic receptors.
D) gap junctions.
E) tight junctions.

Question 73

Which of the following is involved in the sequence of events that triggers synaptic transmission?

A) The action potential
B) The opening of Ca²⁺ channels at the synaptic terminal
C) The entry of Ca²⁺ into the presynaptic terminal
D) Fusion of synaptic vesicles with the presynaptic membrane
E) All of the above

Question 74

Mice with modified NMDA receptors

A) run through mazes more slowly than normal mice do.
B) remember the routes in mazes for longer periods of time than normal mice do.
C) fail to learn tasks.
D) remember the routes in mazes for shorter periods of time than normal mice do.
E) a, c, and d

Question 75

Synaptic clefts can be cleansed of neurotransmitters by means of

A) enzymatic degradation.
B) simple diffusion.
C) active transport.
D) Both a and c
E) All of the above

Question 76

Which of the following neurotransmitters is a peptide?

A) Acetylcholine
B) Norepinephrine
C) Serotonin
D) Glycine
E) Endorphin

Question 77

Long-term potentiation

A) may be involved in learning and memory.
B) involves a decreased postsynaptic response.
C) involves AMPA receptors only.
D) results from low frequency of stimulation.
E) None of the above

Question 78

Which of the following statements about neurons is true?

A) They fire action potentials only on the basis of the number of excitatory inputs they receive.
B) They sum excitatory and inhibitory postsynaptic potentials.
C) The "decision" to fire is made in the dendrites.
D) They make spatial, but not temporal, summations.
E) Both a and c

Question 79

Neurotransmitters

A) have multiple types of receptors.
B) may be excitatory or inhibitory.
C) may have different effects in different tissues.
D) include dopamine and serotonin, which are monoamines.
E) All of the above

Question 80

A postsynaptic cell's processing of information from synapses at different sites is called

A) excitatory postsynaptic potential.
B) inhibitory postsynaptic potential.
C) spatial summation.
D) temporal summation.
E) action potential.