Chapter 7 Quiz, Part 1

An action potential generates local currents that tend to _________ the membrane immediately adjacent to the action potential. A) depolarize B) repolarize C) hyperpolarize D) stabilize E) neutralize

A) depolarize

In the neuromuscular junction, acetylcholine... A) diffuses across the synaptic cleft and binds to Ach receptors on the postsynaptic muscle fiber B) is actively transported across the synaptic cleft and binds to Ach receptors on the postsynaptic muscle fiber C) diffuses across the synaptic cleft and causes Ca+ to diffuse into the postsynaptic muscle fiber D) diffuses across the synaptic cleft and causes Na+ to diffuse out of the postsynaptic muscle fiber E) is actively transported across the synaptic cleft and causes Ca+ to diffuse into the postsynaptic muscle fiber

A) diffuses across the synaptic cleft and binds to Ach receptors on the postsynaptic muscle fiber

When threshold is reached in a neuron, depolarization occurs withing the same amplitude of potential change. This is known as A) the All-or-None Law B) cable properties of axons C) a graded response D) salutatory conduction

A) the All-or-None Law

Acetylcholine has which effect on the postsynaptic neuron? A) Ligand-gated Ca+ channels open and Ca+ diffuses in B) Ligand-gated Na+ channels open and Na+ diffuses in C) Terminal vessels migrate to the plasma membrane D) Voltage-gated Ca+ channels open and Ca+ diffuses in E) Voltage-gated Na+ channels open and Na+ diffuses in

B) Ligand-gated Na+ channels open and Na+ diffuses in

During depolarization, which of the following statements about voltage-gated ion channels is TRUE? A) K+ gates open before Na+ gates B) Na+ gates open before K+ gates C) Na+ and K+ gates open at the same time D) Na+ gates open while K+ gates remain closed E) K+ gates open while Na+ gates remain closed

B) Na+ gates open before K+ gates

The neurotransmitter in the neuromuscular junction... A) causes ligand gated Ca+ channels in the muscle fiber to increase their permeability to Ca+, which depolarizes the postsynaptic membrane B) causes ligand gated Na+ channels in the muscle fiber to increase their permeability to Na+, which depolarizes the postsynaptic membrane C) increases the Ca+ permeability of the presynaptic membrane D) increases the Na+ permeability of the presynaptic membrane E) depolarizes the presynaptic membrane by increasing the permeability of Na+

B) causes ligand gated Na+ channels in the muscle fiber to increase their permeability to Na+, which depolarizes the membrane

What structures are involved in electrical synapses? A) tight junctions B) gap junctions C) desmosomes D) microvilli

B) gap junctions

The period of time when a membrane cannot respond to another stimulus, no matter how strong, is the A) relative refractory period B) All-or-None period C) absolute refractory period D) after-potential period

C) absolute refractory period

The neurotransmitter at the neuromuscular junction is A) dopamine B) adrenaline C) acetylcholine D) histamine E) serotonin

C) acetylcholine

Action potentials arriving at a presynaptic terminal cause A) release of neurotransmitter B) calcium ion channels to close C) calcium ion channels to open D) breakdown of acetylcholine

C) calcium ion channels to open

An action potential ______________ . A) causes the neuron cell membrane to become unable to alter its charge B) causes the outside of the neuron cell membrane to become positively charged in reference to the inside C) causes the inside of the neuron cell membrane to become positively charged in reference to the outside D) causes the inside of the neuron cell membrane to become negatively charged in reference to the outside E) causes the inside of the neuron cell membrane to become neutrally charged in reference to the outside

C) causes the inside of the neuron cell membrane to become positively charged in reference to the outside

What type of cells produce the myelin sheath in the central nervous system (CNS)? A) Schwann cells B) microglia C) oligodendrocytes D) astrocytes

C) oligodendrocytes

Which of the following statements about the resting membrane potential is TRUE? A) the exterior of the cell has a net negative charge and the interior has a net positive charge B) the exterior of the cell has a net negative charge and the interior is neutral C) the exterior of the cell has a net positive charge and the interior has a net negative charge D) the exterior of the cell has a net positive charge and the interior is neutral E) the exterior of the cell is neutral and the interior has a net negative charge

C) the exterior of the cell has a net positive charge and the interior has a net negative charge

An inhibitory postsynaptic potential (IPSP)... A) will make the membrane potential of a neuron's inner cell membrane more positive B) will make the membrane potential of a neuron's outer cell membrane more positive C) will make the membrane potential of a neuron's inner cell membrane more negative D) will make the membrane potential of a neuron's outer cell membrane more negative E) will lower the membrane threshold potential of a neuron

C) will make the membrane potential of a neuron's inner cell membrane more negative

Hyperpolarization that leads to postsynaptic inhibition is a/an A) NMDA B) LTP C) EPSP D) IPSP

D) IPSP

Depolarization of the postsynaptic membrane by an excitatory postsynaptic potential (EPSP) causes _______________. A) the neurons inner cell membrane potential increases B) sodium ions diffuse through the neuron's intracellular fluid of the internode C) repolarization of the neurons inner cell membrane occurs D) the sodium channels open and sodium ions pour into the intracellular fluid E) the potassium channels open and potassium ions pour into the extracellular fluid

D) the sodium channels open and sodium ions pour into the intracellular fluid

Which type of neuroglial cell supports the metabolic needs of the blood-brain barrier? A) oligodendrocytes B) Schwann cells C) microglia D) ependymal cells E) astrocytes

E) astrocytes

Action potentials travel faster on thin, myelinated axons than on thick, myelinated axons. True or False?

False

IPSPs always open K+ channels. True or False?

False

If demyelination occurs, why don't action potentials occur at regions of the axon that were previously myelinated?

These regions lack the appropriate concentration of voltage-gated potassium channels.

If the postsynaptic membrane potential reaches threshold level, an action potential will be produced. True or False?

True

Nicotinic receptors are also ion channels. True or False?

True

The Na+/K+ pump is involved in establishing the resting membrane potential. True or False?

True

The area between the presynaptic nerve cell and the postsynaptic muscle cell is termed the synaptic cleft. True or False?

True

Threshold is the minimum current required for the cell membrane to generate an action potential. True or False?

True

The voltage-gated Na+ channels _______ when the cell reaches +30 mV.

close

Demyelinating diseases cause a(n) ______________ in the conduction velocity of action potentials.

decrease

Action potentials occur ____ _____ __________________ _________ _____ _____ __________ .

in the unmyelinated regions of an axon

When voltage-gated sodium channels are open, sodium flows _________ the neuron making the inside of the cell more _____________

into; positive

The muscarinic ACh receptors are formed from only a single subunit and do not contain _____ ________ like the ___________ ACh receptors. Rather, binding of ACh to the muscarinic receptor activates a complex of proteins in the cell membrane known as ___-_________, because their activity is influenced by GDP and GTP, guanosine nucleotides. There are 3 G-protein subunits: alpha, beta, and gamma. Binding of ACh causes the _______ subunit to dissociate from the other two, which form the _____ _______ complex. Either the alpha subunit or the ______ _________ complex then diffuses through the membrane until it binds to an ion channel and causes it to open or close. Word Bank: G-proteins; alpha; alpha-beta; beta, gamma; nicotinic; ion channels

ion channels nicotinic G-proteins alpha beta, gamma beta, gamma

When K+ diffuses out of the cell, the cell becomes _______ depolarized.

less

When Na+ diffuses into the cell, the cell becomes ________ depolarized.

more

K+ diffusing out of the cell has a ___________ feedback effect on the initial depolarization.

negative

The voltage-gated Na+ channels _______ when the cell membrane reaches threshold level as a result of a stimulus.

open

Na+ diffusing into the cell causes more Na+ gates to open, which is a ___________ feedback loop.

positive

The following information best describes the ___________ phase of an action potential. ~ a membrane potential reading of +10 mV ~ inactivated voltage-gated sodium channels ~ open voltage-gated potassium channels

repolarization