Web connect chapter 12 review

In the CNS, myelin is produced by glial cells called ____________

Oligodendrocytes

Between the nodes of Ranvier are myelin-covered segments of axon encircled by Schwann cells. Which term refers to these segments?

Axon collaterals

Internodes

Synaptic knobs

Synapses

Internodes

The picture shows the most common structural type of neuron. It contains one axon and multiple dendrites, and it is classified as what type of neuron.

Multipolar

Bipolar

Unipolar

Multipolar

True or false: Damaged nerve fibers in the CNS regenerate very fast whereas damaged nerve fibers in the PNS never regenerate.

False

The myelin sheath is composed mostly of which of the following?

Multiple choice question.

Lipids

Proteins

Glycoproteins

Carbohydrates

Lipids

Which best describes an electrical potential?

Multiple choice question.

The movement of charged particles like ions

A positively or negatively charged atom or molecule

A form of potential energy that can produce current

The opposition to the flow of electrical current across a membrane

A form of potential energy that can produce current

Which term refers to the gaps between segments of myelin along an axon?

Multiple choice question.

Initial segments

Synapses

Internodes

Nodes of Ranvier

Nodes of Ranvier

What term refers to the flow of charged particles from one point to another?

Current

True or false: Unmyelinated nerve fibers (axons) in the PNS are enveloped in Schwann cells.

True

Which type of glial cell aids in regeneration of damaged peripheral nerve fibers by forming a regeneration tube to help reestablish the former connection?

Schwann cells

Choose all the factors that influence the speed of nerve signal conduction.

Size of soma

Type of neuron (multipolar vs. unipolar)

Diameter of axon

Presence of myelin

Diameter of axon

Presence of myelin

Choose all that are characteristics of local potentials.

Graded

All-or-none

Decremental

Self-propagating

Graded

Decremental

Choose all that are properties of action potentials.

Graded (amplitude proportional to stimulus strength)

Self-propagating

All or none

Nondecremental (signal maintains amplitude)

Self-propagating

All or none

Nondecremental

Which is true about a neuron with a large diameter, myelinated axon as compared to a neuron with a small diameter, unmyelinated axon?

More neurotransmitter will be released

Signal conduction will be faster

Less neurotransmitter will be released

Signal conduction will be slower

Signal conduction will be faster

3 multiple choice options

Choose all of the following statements that are true about signal conduction along unmyelinated fibers.

A zone of depolarization excites voltage-gated channels immediately distal to the action potential.

The signal conduction in unmyelinated fibers is saltatory.

Unmyelinated fibers have voltage-gated channels along their entire length.

Unmyelinated fibers have voltage-gated channels along their entire length.

A zone of depolarization excites voltage-gated channels immediately distal to the action potential.

Which best describes signal conduction in unmyelinated axons?

a. The signal is transmitted from one node of Ranvier to the next through saltatory conduction.

b. The entire axon depolarizes at the same time.

c. A wave of depolarization opens more voltage-gated channels immediately distal to the action potential.

d. A local potential is passively conducted down the entire length of the axon.

c. A wave of depolarization opens more voltage-gated channels immediately distal to the action potential.

Which statements are true about signal conduction along myelinated fibers?

1. There are few voltage-gated ion channels at the myelin-covered internodes and multiple channels at the nodes of Ranvier.

2. Action potentials occur only at the nodes of Ranvier.

3. Ions can be exchanged with the ECF only at the nodes of Ranvier.

4. No nerve signal conduction occurs at the internodes.

1,2,3

Choose all the statements that characterize neurotransmitters?

1. They are synthesized by presynaptic neurons.

2. They are found in dendrites of postsynaptic neurons.

3. They stimulate the opening of voltage-regulated gates at the postsynaptic membrane.

4. Neurotransmitters stimulate the opening of ligand-gated ion channels.

5. They bind to receptors and alter the physiology of the postsynaptic cell.

They are released in response to stimulation.

1,4,5

In electrical synapses, electrical signals move quickly from cell to cell through which of the following?

Na+-K+ pumps

Gap junctions

Neurotransmitter receptors

Voltage-gated ion channels

Gap junctions

The neurotransmitters glutamate and GABA are examples of which of the following?

Neuropeptides

Amino acids

Bioamines

Glycoproteins

Amino acids

A cholinergic synapse uses which of the following as its neurotransmitter?

Acetylcholine

Endorphin

Norepinephrine

Serotonin

Acetylcholine

Starting with a signal reaching the distal end of the presynaptic axon, indicate the correct order of events that occur during transmission at a cholinergic excitatory synapse.

1. Opening of calcium gates in synaptic knob as nerve signal arrives

2. Exocytosis of ACh; diffusion across synaptic cleft

3. Binding of ACh to receptors on postsynaptic neuron

4. Opening of sodium gates on post-synaptic membrane allowing influx of sodium

5. Depolarization