CH.8 part 2

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

A. The axon would be unable to generate action potentials.

IPSPs (inhibitory postsynaptic potentials) A. are local hyperpolarizations. B. increase membrane permeability to sodium ions. C. block the efflux of calcium ions. C. block the efflux of potassium ions. D. are local depolarizations.

A. are local hyperpolarizations.

How would a chemical that prevents the opening of voltage-regulated Na+ channels affect the function of a neuron? A. neuron will only be capable of producing graded potentials action potentials will lack a repolarization phase B. neuron will automatically and repeatedly produce graded potentials C. neuron will depolarize more rapidly D. neuron will only be able to hyperpolarize

A. neuron will only be capable of producing graded potentials action potentials will lack a repolarization phase

The following are the main steps in the generation of an action potential.1. Sodium channels are inactivated.2. Voltage-gated potassium channels open and potassium moves out of the cell, initiating repolarization.3. Sodium channels regain their normal properties.4. A graded depolarization brings an area of an excitable membrane to threshold.5. A temporary hyperpolarization occurs.6. Sodium channel activation occurs.7. Sodium ions enter the cell and depolarization occurs. The proper sequence of these events is A. 6, 7, 4, 1, 2, 3, 5. B. 4, 6, 7, 1, 2, 3, 5. C. 2, 4, 6, 7, 1, 3, 5. D. 4, 2, 5, 6, 7, 3, 1. E. 4, 6, 7, 3, 2, 5, 1.

B. 4, 6, 7, 1, 2, 3, 5.

If acetylcholine (ACh) causes inhibition of a postsynaptic neuron, to what type of membrane channel did the ACh bind? A. mechanically-regulated channel B. chemically-regulated potassium channel C. voltage-regulated calcium channel D. voltage-regulated sodium channel E. chemically-regulated sodium channel

B. chemically-regulated potassium channel

Graded potentials A. are often all-or-none. B. may be either a depolarization or a hyperpolarization. C. cause repolarization. D. produce an effect that spreads actively across the membrane surface. E. produce an effect that increases with distance from the point of stimulation.

B. may be either a depolarization or a hyperpolarization.

Rapid impulse conduction from "node" to "node" is called A. synaptic transmission. B. saltatory propagation. C. continuous propagation. D. divergent propagation. E. spatial propagation.

B. saltatory propagation.

Cholinergic synapses release the neurotransmitter A. GABA. B. adrenalin. C. acetylcholine. D. norepinephrine. E. serotonin.

C. acetylcholine.

Summation that results from the cumulative effect of multiple synapses at multiple places on the neuron is designated A. hyperpolarization. B. inhibition of the impulse. C. spatial summation. D. temporal summation. E. impulse transmission.

C. spatial summation.

The all-or-none principle states that A. only sensory stimuli can activate action potentials. B. only motor stimuli can activate action potentials. C. the greater the magnitude of the stimuli, the greater the magnitude of the action potential. D. all stimuli great enough to bring the membrane to threshold will produce identical action potentials. E. all stimuli will produce identical action potentials

D. all stimuli great enough to bring the membrane to threshold will produce identical action potentials.

The site in the neuron where EPSPs and IPSPs are integrated is the A. dendritic membrane. B. synaptic terminal. C. chemical synapse. D. axon hillock. E. electrical synapse.

D. axon hillock.

Presynaptic facilitation by serotonin is caused by A. increased extracellular concentration of potassium ion. B. increased extracellular concentration of sodium ion. C. blockage of calcium channels in the presynaptic membrane. D. calcium channels in the presynaptic membrane remaining open longer. D. temporal summation

D. calcium channels in the presynaptic membrane remaining open longer.

The ion that triggers the release of acetylcholine into the synaptic cleft is A. chloride. B. magnesium. C. sodium. D. calcium. E. potassium

D. calcium.

A threshold stimulus is the A. peak of an action potential. B. electrical current that crosses the synaptic cleft. C. hyperpolarization of an axon. D. depolarization necessary to cause an action potential. resting potential.

D. depolarization necessary to cause an action potential. resting potential.

Voltage-gated sodium channels have both an activation gate and a(n) ________ gate. A. repolarization B. swinging C. ion D. inactivation E. threshold

D. inactivation

When cholinergic receptors are stimulated, A. chloride ions enter the postsynaptic neuron. B. chloride ions leave the postsynaptic neuron. C. sodium ions leave the postsynaptic neuron. D. sodium ions enter the postsynaptic neuron. E. norepinephrine deactivates acetylcholine.

D. sodium ions enter the postsynaptic neuron.

The effect that a neurotransmitter has on the postsynaptic membrane depends on A. the characteristics of the receptors. B. the frequency of neurotransmitter release. C. the nature of the neurotransmitter. D. the quantity of neurotransmitters released. E. All of the answers are correct.

E. All of the answers are correct.

EPSPs (excitatory postsynaptic potentials) occur when A. chloride ions enter a cell. B. more potassium ions than usual leak out of a cell. C. more calcium ions than usual leak out of a cell. D. hyperpolarizations occur. E. extra sodium ions enter a cell.

E. extra sodium ions enter a cell.

The same ________ can have different effects depending on the properties of the ________. A. receptor; neurotransmitter B. hormone; neurotransmitter C. substrate; receptor D. propagation; neurotransmitter E. neurotransmitter; receptor

E. neurotransmitter; receptor

Adrenergic synapses release the neurotransmitter A. dopamine. B. GABA. C. serotonin. D. acetylcholine. E. norepinephrine.

E. norepinephrine.