Nervous System & Muscle Quiz
- 1.Which of the following does not form part of the thin filaments of a muscle cell?
- A.
Actin
- B.
Troponin
- C.
Tropomyosin
- D.
Myosin
- E.
Calcium-binding site
- 2.During the contraction of a vertebrate skeletal muscle fiber, calcium ions
- A.
Break the cross-bridges as a cofactor in the hydrolysis of ATP.
- B.
Bind to the troponin complex, which leads to the exposure of the myosin-binding sites.
- C.
Transmit the action potential across the neuromuscular junction.
- D.
Spread the action potential through the T tubules.
- E.
Reestablish the polarization of the plasma membrane following an action potential.
- 3.Which of the following is the correct sequence that occurs during the excitation and contraction of a muscle cell? 1. Tropomyosin shifts and unblocks the cross-bridge binding sites. 2. Calcium is released and binds to the troponin complex. 3. T tubules depolarize the sarcoplasmic reticulum. 4. The thin filaments are ratcheted across the thick filaments by the heads of the myosin molecules using energy from ATP. 5. An action potential in a motor neuron causes the axon to release acetylcholine, which depolarizes the muscle cell membrane.
- A.
1, 2, 3, 4, 5
- B.
2, 1, 3, 5, 4
- C.
2, 3, 4, 1, 5
- D.
5, 3, 1, 2, 4
- E.
5, 3, 2, 1, 4
- 4.The general functions of the nervous system include which of the following? I. integration II. motor output III. sensory input
- A.
I only
- B.
II only
- C.
III only
- D.
I and II only
- E.
I, II, and III
- 5.Most of the neurons in the human brain are
- A.
Sensory neurons.
- B.
Motor neurons.
- C.
Interneurons.
- D.
Auditory neurons.
- E.
Olfactory neurons.
- 6.Most of the organelles in a neuron are located in the
- A.
Dendritic region.
- B.
Axon hillock.
- C.
Axon.
- D.
Cell body.
- E.
Axon terminals.
- 7.For a neuron with an initial membrane potential at -70 mV, an increase in the movement of potassium ions out of that neuron's cytoplasm would result in
- A.
Depolarization of the neuron.
- B.
Hyperpolarization of the neuron.
- C.
The replacement of potassium ions with sodium ions.
- D.
The replacement of potassium ions with calcium ions.
- E.
The neuron switching on its sodium-potassium pump to restore the initial conditions.
- 8.The operation of the sodium-potassium pump moves
- A.
Sodium and potassium ions into the cell.
- B.
Sodium and potassium ions out of the cell.
- C.
Sodium ions into the cell and potassium ions out of the cell.
- D.
Sodium ions out of the cell and potassium ions into the cell.
- E.
Sodium and potassium ions into the mitochondria.
- 9.Action potentials move along axons
- A.
More slowly in axons of large than in small diameter.
- B.
By the direct action of acetylcholine on the axon membrane.
- C.
By activating the sodium-potassium pump at each point along the axon membrane.
- D.
More rapidly in myelinated than in non-myelinated axons.
- E.
By reversing the concentration gradients for sodium and potassium ions.
- 10.A toxin that binds specifically to voltage-gated sodium channels in axons would be expected to
- A.
Prevent the hyperpolarization phase of the action potential.
- B.
Prevent the depolarization phase of the action potential.
- C.
Prevent graded potentials.
- D.
Increase the release of neurotransmitter molecules.
- E.
Have most of its effects on the dendritic region of a neuron.
- 11.Action potentials are normally carried in only one direction: from the axon hillock toward the axon terminals. If you experimentally depolarize the middle of the axon to threshold, using an electronic probe, then
- A.
No action potential will be initiated.
- B.
An action potential will be initiated and proceed only in the normal direction toward the axon terminal.
- C.
An action potential will be initiated and proceed only back toward the axon hillock.
- D.
Two action potentials will be initiated, one going toward the axon terminal and one going back toward the hillock.
- E.
An action potential will be initiated, but it will die out before it reaches the axon terminal.
- 12.Saltatory conduction is a term applied to conduction of impulses
- A.
Across electrical synapses.
- B.
An action potential that skips the axon hillock in moving from the dendritic region to the axon terminal.
- C.
Rapid movement of an action potential reverberating back and forth along a neuron.
- D.
Jumping from one neuron to an adjacent neuron.
- E.
Jumping from one node of Ranvier to the next in a myelinated neuron.
- 13.The steps below refer to various stages in transmission at a chemical synapse: 1. Neurotransmitter binds with receptors associated with the postsynaptic membrane. 2. Calcium ions rush into neuron's cytoplasm. 3. An action potential depolarizes the membrane of the axon terminal. 4. The ligand-gated ion channels open. 5. The synaptic vesicles release neurotransmitter into the synaptic cleft. Which sequence of events is correct?
- A.
1 → 2 → 3 → 4 → 5
- B.
2 → 3 → 5 → 4 → 1
- C.
3 → 2 → 5 → 1 → 4
- D.
4 → 3 → 1 → 2 → 5
- E.
5 → 1 → 2 → 4 → 3
- 14.The activity of acetylcholine in a synapse is terminated by
- A.
Its active transport across the presynaptic membrane.
- B.
Its diffusion across the presynaptic membrane.
- C.
Its active transport across the postsynaptic membrane.
- D.
Its diffusion across the postsynaptic membrane.
- E.
Its degradation by a hydrolytic enzyme on the postsynaptic membrane.
- 15.Neurotransmitters categorized as inhibitory would be expected to
- A.
Act independently of their receptor proteins.
- B.
Close potassium channels.
- C.
Open sodium channels.
- D.
Close chloride channels.
- E.
Hyperpolarize the membrane.
- 16.When several EPSPs arrive at the axon hillock from different dendritic locations, depolarizing the postsynaptic cell to threshold for an action potential, this is an example of
- A.
Temporal summation.
- B.
Spatial summation.
- C.
Tetanus.
- D.
The refractory state.
- E.
An action potential with an abnormally high peak of depolarization.
- 17.When several IPSPs arrive at the axon hillock rapidly in sequence from a single dendritic location, hyperpolarizing the postsynaptic cell more and more and thus preventing an action potential, this is an example of
- A.
Temporal summation.
- B.
Spatial summation.
- C.
Tetanus.
- D.
The refractory state.
- E.
An action potential with an abnormally high peak of depolarization.
- 18.What happens when a neuron's membrane depolarizes?
- A.
There is a net diffusion of Na+ out of the cell.
- B.
The equilibrium potential for K+ becomes more positive.
- C.
The neuron's membrane voltage becomes more positive.
- D.
The neuron becomes less likely to generate an action potential.
- E.
The inside of the cell becomes more negative relative to the outside.
- 19.Why are action potentials usually conducted in only one direction along an axon?
- A.
The nodes of Ranvier can conduct potentials in only one direction.
- B.
The brief refractory period prevents reopening of voltage-gated Na+ channels.
- C.
The axon hillock has a higher membrane potential than the terminals of the axon.
- D.
Ions can flow along the axon in only one direction.
- E.
Voltage-gated channels for both Na+ and K+ open in only one direction.
- 20.Where are neurotransmitter receptors located?
- A.
On the nuclear membrane
- B.
At nodes of Ranvier
- C.
On the postsynaptic membrane
- D.
On the membranes of synaptic vesicles
- E.
In the myelin sheath