Chapter 12 mastering a & p

In a(n) ________ synapse, current flows directly between cells. a) chemical b) cell c) electrical d) osmotic e) gap

c) electrical

The sum of the electrical and chemical forces acting on an ion is known as its a) summation difference. b) permeability gradient. c) electrochemical gradient. d) thermodynamic difference. e) action potential.

c) electrochemical gradient

Regions of the CNS where neuron cell bodies dominate constitute the ________ matter. a) ganglion b) neural c) gray d) brain e) white

c) gray

If a nerve cell receives many IPSPs in different locations at the same time, __________. a) the membrane potential will depolarize b) the nerve cell will approach threshold c) it will show spatial summation

c) it will show spatial summation

After acetylcholinesterase acts, the synaptic terminal a) reabsorbs the acetate. b) reabsorbs the acetylcholine. c) reabsorbs the choline. d) reabsorbs axoplasm. e) pinches off and a new terminal grows.

c) reabsorbs the choline

Regions of the CNS with an abundance of myelinated axons constitute the ________ matter. a) ganglion b) white c) neural d) gray e) brain

b) white

The axon is connected to the soma at the

axon hillock

Type ________ fibers have the largest diameter axons. a) F b) A c) C d) S e) B

b) A

A neuron that receives neurotransmitter from another neuron is called a) a satellite cell. b) the postsynaptic neuron. c) the presynaptic neuron. d) the motor neuron. e) an oligodendrocyte.

b) a postsynaptic neuron

Which of these substances is considered a neuromodulator? a) norepinephrine b) endorphins c) nitric oxide d) acetylcholine

b) endorphins

EPSPs (excitatory postsynaptic potentials) occur when e) hyperpolarizations occur. a) chloride ions enter a cell. b) extra sodium ions enter a cell. c) more potassium ions than usual leak out of a cell. d) more calcium ions than usual leak out of a cell.

b) extra sodium ions enter the cell

Voltage-gated channels are present a) on the soma of neurons. b) in the membrane that covers axons. c) on the surface of dendrites. d) along the perikaryon of neurons. e) at the motor end plate.

b) in the membrane that covers axons

Which type of ion channel is always open? a) mechanically-gated b) leak c) chemically-gated d) voltage-gated

b) leak

The sodium-potassium ion exchange pump a) depends on a hydrogen gradient for energy. b) moves sodium and potassium opposite to the direction of their electrochemical gradients. c) must reestablish ion concentrations after each action potential. d) transports sodium ions into the cell during depolarization. e) transports potassium ions out of the cell during repolarization.

b) moves sodium and potassium opposite to the direction of their electrochemical gradients

The neurotransmitter GABA blocks presynaptic voltage-gated calcium channels. Consequently, GABA produces __________. a) EPSPs b) presynaptic inhibition c) IPSPs d) presynaptic facilitation

b) presynaptic inhibition

Rapid impulse conduction from "node" to "node" is called a) synaptic transmission. b) saltatory propagation. c) divergent propagation. d) spatial propagation. e) continuous propagation.

b) saltatory propagation

How would the absolute refractory period be affected if voltage-regulated sodium channels failed to inactivate? a) It would last indefinitely. b) It would be much briefer. c) It would be basically unaffected.

a) it would last indefinitely

Which of these neurotransmitters is released at CNS adrenergic synapses? a) norepinephrine b) serotonin c) adrenaline d) GABA

a) norepinephrine

When cholinergic receptors are stimulated, a) sodium ions enter the postsynaptic neuron. b) chloride ions leave the postsynaptic neuron. c) norepinephrine deactivates acetylcholine. d) chloride ions enter the postsynaptic neuron. e) sodium ions leave the postsynaptic neuron.

a) sodium ions enter the postsynaptic neuron

The ________ nervous system controls the skeletal muscles A) somatic b) autonomic c) parasympathetic d) sympathetic e) afferent

a) somatic

functions of the neuroglia (4)

-maintenance of blood-brain barrier -phagocytosis -support -secretion of cerebrospinal fluid

The period during which an excitable membrane can respond again, but only if the stimulus is greater than the threshold stimulus, is the ________ period. a) relative refractory b) resting c) stationary d) lag e) absolute refractory

A) relative refractory

When you take a pain reliever, which of the following best describes, in general terms, how this affects the threshold of neurons? A) Taking a pain reliever decreases the threshold. B) Taking a pain reliever increases the threshold. C) Taking a pain reliever does not affect the threshold of neurons. D) Taking a pain reliever affects the all-or-none principle of neurons. So, neurons reaching threshold send an action potential at 50%.

B) taking a pain reliever increases the threshold

A shift of the resting transmembrane potential toward 0 mV is called a) polarization. b) hyperpolarization. c) potential difference. d) depolarization. e) repolarization.

D) depolarization

The tiny gaps between adjacent Schwann cells are called The tiny gaps between adjacent Schwann cells are called terminals. A) vesicles. b) axolemma. c) neurillema. d) nodes of Ranvier.

D) nodes of Renvier

________ line the brain ventricles and spinal canal.

Ependymal cells

________ account for roughly half of the volume of the nervous system.

Neuroglia

Clusters of RER and free ribosomes in neurons are called

Nissl bodies

Glial cells that surround the neurons in ganglia are

Satellite cells

what are the two types of neuroglia that are found in the PNS

Satellite cells and Shwann cells

The neurilemma of axons in the peripheral nervous system is formed by

Shwann cells

True or False Dendrites contain chemically gated ion channels

True

The ________ division of the nervous system carries motor commands to muscles and glands. A) efferent b) spinal c) afferent D) peripheral e) autonomic

a) efferent

If EPSPs summate to a sustained value above threshold, then the initial segment will __________. a) generate a string of action potentials b) generate larger than normal action potentials c) hyperpolarize d) be inhibited

a) generate a string of action potentials

Voltage-gated sodium channels have both an activation gate and a(n) ________ gate. a) inactivation b) ion c) repolarization d) swinging E) threshold

a) inactivation

________ carry sensory information to the CNS.

afferent

The ________ nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity.

autonomic

The sodium-potassium exchange pump stabilizes resting potential of the neuron membrane at about __________. a) -90 mV b) +66 mV c) -70 mV d) -20 mV

c) -70 mV

________ open or close in response to binding specific molecules. a) Leak channels b) Voltage-gated channels c) Chemically gated channels d) Voltage-gated and chemically gated channels e) Activated channels

c) Chemically gated channels

Synaptic delay is caused by a) the lack of permeability of the post-synaptic membrane. b) binding of acetylcholine to post-synaptic receptors. c) calcium influx and neurotransmitter release. d) production and transport of neurotransmitter within the neuron. e) neurotransmitter diffusion.

c) calcium influx and neurotransmitter release

Branches that may occur along an axon are called

collaterals

The following are the steps involved in transmission at a cholinergic synapse. What is the correct sequence for these events? 1. Chemically-gated sodium channels on the postsynaptic membrane are activated. 2. Calcium ions enter the synaptic terminal. 3. Acetylcholinesterase hydrolyzes acetylcholine. 4. An action potential depolarizes the synaptic terminal at the presynaptic membrane. 5. The pre-synaptic terminal reabsorbs choline. 6. Acetylcholine is released from storage vesicles by exocytosis. 7. Acetylcholine binds to receptors on the postsynaptic membrane. 8. Calcium ions are removed from the cytoplasm of the pre- synaptic terminal. The following are the steps involved in transmission at a cholinergic synapse. What is the correct sequence for these events? a) 2, 5, 4, 6, 7, 1, 8, 3 b) 4, 2, 6, 7, 8, 5, 3, 1 c) 6, 4, 2, 7, 1, 8, 3, 5 d) 4, 2, 6, 7, 1, 8, 3, 5 e) 2, 4, 6, 7, 1, 8, 3, 5

d) 4,2,6,7,1,8,3,5

Cholinergic synapses release the neurotransmitter a) norepinephrine. b) serotonin. c) GABA. d) acetylcholine. e) adrenalin.

d) acetylcholine

Compared to type A axons, type C axons are __________. a) smaller diameter b) slower propagating c) unmyelinated d) All of the listed responses are correct.

d) all of the listed responces are correct

IPSPs (inhibitory postsynaptic potentials) a) block the efflux of calcium ions. b) block the efflux of potassium ions. c) increase membrane permeability to sodium ions. d) are local hyperpolarizations. e) are local depolarizations.

d) are local hyperpolarizations

When a person has a stroke, blood leaks into the brain tissue. Which type of neuroglia cells would make structural repairs to the damage? A) oligodendrocytes B) satellite cells c) ependymal cells d) astrocytes

d) astrocytes

The simplest level of information processing takes place at the __________. a) dendrites b) axon terminals c) soma d) axon hillock

d) axon hillock

Ion channels that are always open are called ________ channels. a) local b) regulated c) active d) leak e) gated

d) leak

When pressure is applied to neural tissue, all of the following effects are possible except When pressure is applied to neural tissue, all of the following effects are possible except a)glial cells degenerate. b)a change in neuron excitability. c)a decrease in available oxygen. d)neurons are triggered to divide. e)a decrease in blood flow.

d) neurons are triggered to divide

Adrenergic synapses release the neurotransmitter a) dopamine. b) serotonin. c) acetylcholine. d) norepinephrine. e) GABA.

d) norepinephrine

What most directly causes the exocytosis of Ach in synaptic vesicles? a) active transport of calcium ions out of the axon terminal b) arrival of an action potential at the presynaptic terminal c) depolarization of the membrane at the axon terminal d) arrival of calcium ions in the axon terminal

d) the arrival of calcium ions in the axon terminal

Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons? a) The absolute refractory period would be shorter than normal. b) Neurons would depolarize more rapidly. c) Action potentials would lack a repolarization phase. d) The axon would be unable to generate action potentials. e) None, because the chemically gated sodium channels would still function.

d) the axon would be unable to generate action potentials

The period during which an excitable membrane cannot respond to further stimulation is the ________ period. a) stationary b) lag c) relative refractory d) resting e) absolute refractory

e) absolute refractory

Any stimulus that opens a ________ ion channel will produce a graded potential. a) chemically gated b) sodium c) mechanically gated d) voltage-gated e) All of the answers are correct.

e) all of the answers are correct

Ions can move across the plasma membrane in which of the following ways? a) through voltage-gated channels as in the action potential B) by ATP-dependent ion pumps like the sodium-potassium exchange pump c) through passive or leak channels d) through chemically gated channels as in neuromuscular transmission e) All of the answers are correct.

e) all of the answers are correct

The effect that a neurotransmitter has on the postsynaptic membrane depends on the a) quantity of neurotransmitters released. b) frequency of neurotransmitter release. c) nature of the neurotransmitter. d) characteristics of the receptors. e) All of the answers are correct.

e) all of the answers are correct

During propagation of the action potential, __________. a) after threshold is reached, voltage-gated sodium b) channels open rapidly c)local currents depolarize a spot adjacent to the active zone d)the axon hillock depolarizes the initial segment e)All of the listed responses are correct.

e) all of the listed responses are correct

In the peripheral nervous system, Schwann cells participate in the repair of damaged nerves by a) producing more satellite cells that fuse to form new axons. b) producing new axons. c) regenerating cell bodies for the neurons. d) clearing away cellular debris. e) forming a cellular cord that directs axonal regrowth.

e) forming a cellular cord that directs axonal regrowth

________ channels open or close in response to physical distortion of the membrane surface. a) Chemically gated b) Voltage-gated c) Active d) Leak E) Mechanically gated

e) mechanically gated

Summation that results from the cumulative effect of multiple synapses at multiple places on the neuron is designated a) hyperpolarization. b) impulse transmission. c) inhibition of the impulse. d) temporal summation. e) spatial summation.

e) spatial summation

When a second EPSP (excitatory postsynaptic potential) arrives at a single synapse before the effects of the first have disappeared, what occurs? a) temporal summation b) hyperpolarization c) decrease in speed of impulse transmission d) spatial summation e) inhibition of the impulse

e) temporal summation

Small, wandering cells that engulf cell debris and pathogens in the CNS are called

microglia

Most CNS neurons fall into which structural category?

multipolar

The most abundant class of neuron in the central nervous system is

multipolar nuerons

what is contained inside axon terminals

neurotransmitter molecules

The cytoplasm that surrounds the nucleus of a neuron is called the

perikaryon

The rabies virus travels to the CNS via

retrograde axoplasmic transport

________ nerves are nerves that connect to the spinal cord.

spinal

Axons terminate in a series of fine extensions known as

telodendria

Neurons in which dendritic and axonal processes are continuous and the soma lies off to one side are called

unipolar

sensory neurons

unipolar