NEURON II ( j.ang)

Bogdan Koczanowski Ph.D.

1. Bundles of axons in the spinal cord are called

a) nuclei.
b) tracts.
c) centers.
d) ganglia.
e) nerves.
2. Most neurons lack centrioles. This observation explains

a) the ability of neurons to produce an axoplasmic flow.
b) why neurons grow such long axons.
c) the conducting ability of neurons.
d) why neurons cannot regenerate.
e) the ability of neurons to communicate with each other.
3. Each of the following is an example of a neuroeffector junction, except the junction between a neuron and a(n)

a) neuron.
b) skeletal muscle.
c) exocrine gland.
d) endocrine gland.
e) smooth muscle.
4. How does blocking the ability for retrograde flow in an axon affect the activity of a neuron?

a) The neuron is unable to produce neurotransmitters.
b) The soma is unable to export products to the synaptic knobs.
c) The neuron is unable to depolarize when stimulated.
d) The neuron is unable to produce action potentials.
e) The soma is unable to respond to changes in the distal end of the axon.
5. Many medications introduced into the blood stream cannot directly affect the neurons of the CNS because

a) oligodendrocytes form a continuous myelin sheath around the axons.
b) the neurolemma is impermeable to all types of molecules.
c) the lining of the capillaries in the CNS forms a blood-brain barrier.
d) the ependymal cells restrict the flow of interstitial fluid between the capillaries and the neurons.
e) Glial cells (like the astrocytes) form a physical barrier between the blood vessels and the neuron's membrane..
6. Damage to large numbers of oligodendrocytes in the CNS would result in

a) loss of the structural framework of the brain.
b) decreased speed of action potential conduction.
c) a breakdown of the blood-brain barrier.
d) decreased production of cerebrospinal fluid.
e) inability to produce scar tissue at the site of an injury.
7. Damage to ependymal cells would affect the

a) transport of neurotransmitters within axons.
b) formation of myelin sheaths.
c) repair of axons.
d) formation of ganglia.
e) formation of cerebrospinal fluid.
8. Changes in transmembrane potentials

a) can open chemically regulated channels.
b) can only produce an action potential.
c) can open voltage regulated channels.
d) can only produce a local potential.
e) cannot alter the resting membrane potential.
9. Graded potentials

a) produce an effect that spreads actively across the membrane surface.
b) involve repolarization.
c) produce an effect that increases with distance from the point of stimulation.
d) are all-or-none.
e) may involve either depolarization or hyperpolarization.
10. If the axolemma becomes more permeable to potassium ion

a) it will take a stimulus of larger magnitude to initiate an action potential.
b) the membrane will depolarize more rapidly.
c) the membrane will become hypopolarized.
d) the inside of the membrane will become more positively charged.
e) the hyperpolarization at the end of the action potential will not occur.
11. If the sodium-potassium pumps in the cell membrane fail to function, all of the following occur, except:

a) The membrane will lose its capacity to generate action potentials.
b) The neuron will lose its ability to regenerate.
c) The intracellular concentration of sodium ions will increase.
d) The inside of the membrane will have a resting potential that is more positive than normal.
e) The extracellular concentration of potassium ions will increase.
12. How would the absolute refractory period be affected if voltage-regulated sodium channels failed to become inactivated?

a) It would be the same.
b) It would be shorter.
c) It would be longer.
13. In which of the following would the rate of impulse conduction be the ?

a) a myelinated fiber
b) a nonmyelinated fiber
14. In which of the following would the rate of impulse conduction be the ?

a) a nonmyelinated fiber 25 cm long
b) a nonmyelinated fiber 2 microns in diameter
c) a myelinated fiber 20 microns in diameter
d) a nonmyelinated fiber 20 microns in diameter
e) a myelinated fiber 2 microns in diameter
15. When cholinergic receptors are stimulated

a) sodium ions leave the postsynaptic neuron.
b) chloride ions enter the postsynaptic neuron.
c) potassium ions leave the postsynaptic neuron.
d) potassium ions enter the postsynaptic neuron.
e) sodium ions enter the postsynaptic neuron.
16. If the presynaptic membrane of a motor neuron suddenly became permeable to calcium ion

a) no neurotransmitter would be released.
b) the motor end plate would be stimulated.
c) the motor end plate would be inhibited.
d) the neuron would fatigue.
e) the neuron would not be able to stimulate the muscle.
17. Presynaptic facilitation occurs when

a) calcium channels in the presynaptic membrane are inhibited.
b) calcium channels in the presynaptic membrane remain open longer.
c) temporal summation occurs.
d) extracellular concentration of sodium increases.
e) extracellular concentration of potassium increases.
18. Which type of membrane channels are found at label 1?



a) chemically-regulated Na+ and K+ channels
b) voltage-regulated Na+ and K+ channels
c) chemically-regulated Na+ and K+ channels and voltage-regulated Na+ and K+ channels
d) only Na+ and K+ leak channels
e) chemically-regulated Na+ and K+ channels and voltage-regulated Na+, K+, and Ca++ channels
19. Which type of membrane channels are found at label 2?

a) only Na+ and K+ leak channels
b) voltage-regulated Na+ and K+ channels
c) chemically-regulated Na+ and K+ channels and voltage-regulated Na+, K+, and Ca++ channels
d) chemically-regulated Na+ and K+ channels
e) chemically-regulated Na+ and K+ channels and voltage-regulated Na+ and K+ channels
20. Which type of membrane channels are found at label 4?

a) chemically-regulated Na+ and K+ channels and voltage-regulated Na+ and K+ channels
b) only Na+ and K+ leak channels
c) chemically-regulated Na+ and K+ channels and voltage-regulated Na+, K+, and Ca++ channels
d) voltage-regulated Na+ and K+ channels
e) chemically-regulated Na+ and K+ channels
21. Which areas of the neuron are capable of conducting an action potential?

a) 3 and 4
b) 3, 4, and 5
c) 1 and 2
d) 2 and 3
22. Identify the structure labeled "1".

a) axon
b) hillock
c) dendrite
d) soma
e) synaptic knob
23. Which area of the graph shows when voltage-regulated sodium channels open?



a) 4
b) 3
c) 1
d) 5
e) 2
24. Which area of the graph shows an increase in K+ permeability?

a) 1
b) 4
c) 3
d) 2
e) 5
25. Which area of the graph shows when chemically-regulated sodium channels are open?

a) 5
b) 1
c) 2
d) 4
e) 3
26. Which area of the graph shows when voltage-regulated potassium channels begin to close?

a) 4
b) 3
c) 2
d) 5
e) 1
27. What is occurring at the area labeled #5?

a) excess polarization of the axon has occurred
b) chemically-regulated K+ channels have opened
c) an inhibitory stimulus has occurred
d) sodium has been pumped out of the neuron
e) excess potassium has leaked out causing hyperpolarization
28. Tom's father suffers a stroke that leaves him partially paralyzed on his right sidWhat type of glial cell would you expect to find in increased numbers in the area of the brain that is affected by the stroke?

a) microglia
b) oligodendrocytes
c) astrocytes
d) satellite cells
e) ependymal cells
29. Tetrodotoxin is a toxin that blocks the chemically activated sodium channels from opening. What effect would this have on the function of neurons?

a) The toxin would not interfere with neuron function because the voltage-regulated sodium channels would still function.
b) Neurons would depolarize more rapidly.
c) Action potentials would lack a repolarization phase.
d) The absolute refractory period would be shorter than normal.
e) The neuron would be unable to propagate action potentials.
30. A molecule that interferes with the formation of cAMP would

a) prevent acetylcholine from stimulating a postsynaptic membrane.
b) cause spasms in muscles regulated by acetylcholine.
c) prevent norepinephrine from stimulating a postsynaptic membrane.
d) have no effect on an adrenergic synapse.
e) result in increased breakdown of norepinephrine.
31. In a condition known as hypocalcemia, the level of calcium ions in the blood and interstitial fluid is lower than normal. How would this condition affect the function of the nervous system?

a) Neurons would generate action potentials spontaneously.
b) Depolarizing events would occur more frequently at the postsynaptic membrane.
c) Potassium channels would fail to open.
d) Cholinergic synapses would be more active.
e) Less neurotransmitter would be released from a presynaptic membrane in response to an action potential.
This is more feedback!
This is the feedback!



Back to Top