Chapter 2

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What is the correct sequence of structures encountered by neural information as it travels along a neuron?

dendrites to soma to axon to terminal buttons

dendrites to soma to terminal buttons to axon

soma to axon to dendrites to terminal buttons

terminal buttons to axon to soma to dendrites

Microtubules are slender tubes that

carry information from the cell body to the terminal button.

transport substances within the cell.

resemble tree branches and receive incoming messages.

wrap around portions of the axon.

Which of the following are the least similar in their functions?

lysosomes and mitochondria

axons and dendrites

chromosomes and genes

nucleolus and ribosomes

Which of these alternatives does not provide support to neurons?

oligodendrocyte

astrocyte

node of Ranvier

glia

When nerves in the PNS are damaged, Schwann cells

produce scar tissue.

secrete enzymes that stimulate neurons to divide.

form cylinders to guide the new axon sprouts.

manufacture extra myelin.

Fewer substances enter or leave the brain across the blood-brain barrier in the _____ because the walls of the capillaries _____.

PNS; have gaps

PNS; do not have gaps

CNS; have gaps

CNS; do not have gaps

When the transmitter substance is released at a particular synapse, two possible effects occur:

sympathetic or parasympathetic.

electrical or chemical.

positive or negative.

excitatory or inhibitory.

If the membrane of an axon receives a sufficiently large depolarization, the resulting rapid reversal of charge is called a(n)

threshold of excitation.

membrane potential.

action potential.

resting potential shift.

The membrane potential is the result of two forces:

diffusion and electrostatic pressure.

hyperpolarization and depolarization.

equilibrium and inertia.

the resting potential and the threshold of excitation.

Sodium-potassium transporters keep the intracellular concentration of

Na+ low.

K+ low.

Na+ high.

Cl- high.

All of the following are true about conduction of an action potential in a myelinated axon except:

The transmission follows the all-or-none law.

Conduction of the message under the myelin segment is via passive cable properties.

Saltatory transmission is more energy efficient but slower than transmission in unmyelinated axons.

Action potentials occur only at the nodes of Ranvier.

Saltatory conduction is advantageous because

it is unaffected by diseases that damage myelin.

it permits myelinated axons to transmit action potentials almost as fast as unmyelinated axons.

nodes of Ranvier are bypassed.

less energy is required to operate the sodium-potassium transporters.

Which of the following statements is not true of chemical involved in communication?

Most neuromodulators are composed of peptides.

Hormones travel in the bloodstream and affect distant receptors.

Pheromones are chemical that are released by endocrine glands.

Ligands that activate receptors can be found in the body, in nature, and in the laboratory.

Select the correct statement about the synapse.

Cisternae are involved in production of large synaptic vesicles.

Small vesicles typically contain neuropeptides.

Mitochondria play a role in the repackaging of transmitters into vesicles.

Most vesicles congregate near the part of the presynaptic membrane called the release zone.

Synaptic vesicles are produced in the __________ and are transported to the __________.

cytoplasm; dendrites

soma; terminal buttons

dendrites; release zone

synapse; extracellular fluid

What ion plays a crucial role in propelling synaptic vesicles toward the presynaptic membrane?

Na+

Cl-

Ca2+

K-

The membrane of synaptic vesicles is recycled by

being incorporated into the membrane of the terminal button, after which small buds pinch off into the cytoplasm.

being incorporated into the membrane of the terminal button, after which it subdivides into replicas of itself.

resealing their membranes and spontaneously reproducing transmitter substance.

fusing with mitochondria, which provide energy to regenerate.

Postsynaptic receptors bind with molecules of transmitter substance and

transport them to synaptic vesicles.

open neurotransmitter-dependent ion channels.

release them during an EPSP or IPSP.

deactivate them through reuptake.

The acetylcholine receptor studied in the electric ray

is a metabotropic receptor.

opens potassium channels when stimulated.

is linked to a G protein that activates an enzyme in the membrane.

opens ion channels directly when stimulated.

All of the following are true about metabotropic receptors except:

When stimulated, they require the cell to expend energy.

They are found on the postsynaptic membrane but not the presynaptic membrane.

They open ion channels indirectly via activation of second messengers.

They are located in close proximity to G proteins.

During an EPSP

Na+ enters the cell.

K+ enters the cell.

Na+ leaves the cell.

Cl- leaves the cell.

At most synapses, postsynaptic potentials are terminated by

reuptake.

enzymatic deactivation.

ionic flow.

phagocytosis.

A neuron's own transmitter substance, detected by its autoreceptors,

initiates changes in the local membrane potential.

opens the gates of neurotransmitter- dependent ion channels.

facilitates the synthesis of other transmitter substances.

regulates internal processes.

Peptides

stimulate metabotropic receptors that alter the activity of the cell's nucleus.

are small fat-soluble molecules.

include hormones secreted by the sex glands and the adrenals.

are synthesized from cholesterol.