Human Anatomy and Physiology II
Exam 1, Version 6 - Feb. 17, 1997
Dr. Chabot
Multiple Choice (@2 points): Circle the letter of the one best answer. GOOD LUCK!
Answer only 30 out of 33! The first 30 answered will be graded.
1. At rest, approximately what percent of our oxygen intake is consumed by the brain?
A. 5%
B. 10%
C. 20%
D. 50%
2. When an action potential passes over the surface of a synaptic knob, the contents of vesicles are released in response to the presence of
A. calcium ions
B. sodium ions
C. neurotransmitters
D. neuropeptides
3. Assume that an axon is artificially stimulated about halfway along its length. Which of the following will occur?
A. Negative organic (Pr-) ions move out of the cytoplasm to the outside of the axon.
B. The impulse may travel in both directions.
C. Sodium ions cross the membrane out of the cytoplasm; potassium ions move across the membrane into the cytoplasm of the axon.
D. The impulse will travel in only one direction because of absolute and relative refractory.
4. Where would you look in the spinal cord for the cell bodies of motor neurons?
A. ventral gray horn
B. lateral gray horn
C. white matter
D. dorsal root ganglion
5. A nerve cell membrane may become repolarized from a depolarized state as a result of
A. the flow of K out of the cell
B. the flow of Na into the cell
C. the relative ease with which potassium ions diffuse through membranes
D. totally preventing sodium ions from passing through the membrane
6. Oligodendrocytes function to
A. nourish the cell bodies of sensory neurons
B. nourish the cell bodies of motor neurons
C. insulate axons in the CNS
D. insulate axons in th peripheral nervous system
7. Neurotransmitters are produced and packaged in the ________ of neurons.
A. axon
B. synapse
C. mitochondria
D. cell body
8. The units used to measure the resting potential of a nerve fiber are
A. watts
B. millivolts
C. millimeters
D. calories
9. Action potentials:
I. can be summed.
II. vary in size.
III. are conducted decrementally (decrease in amplitude with distance).
IV. usually last much longer than graded potentials.
A. I and III only
B. II and IV only
C. I, II, and III only
D. none of the above
10. When an inhibitory neurotransmitter combines with a receptor site on a postsynaptic membrane an:
A. influx (inward flow) of potassium ions occurs.
B. influx of sodium ions occurs.
C. efflux of sodium ions occurs.
D. efflux (outward flow) of potassium ions occurs.
11. The medulla oblongata serves all the following functions except:
A. regulates respiratory functions
B. regulates heart rate
C. regulates liver functions
D. regulates the diameter of arterioles
12. If a series of post synaptic potentials that sum is great enough to surpass the threshold level at the axon hillock, the strength of the action potential generated will be:
A. zero.
B. proportional to the strength of the post synaptic potentials.
C. inversely proportional to the strength of the post synaptic potentials.
D. the same, no matter what the strength of the post synaptic potentials
13. Depolarization of the neuronal membrane may be produced by any factor that:
A. increases the membrane's permeability to sodium ions.
B. decreases the membrane's permeability to sodium ions.
C. stimulates the sodium-potassium pump.
D. increases the membrane's permeability to potassium ions.
14. The ventral root of each spinal nerve:
I. carries sensory information from peripheral receptors.
II. contains the processes (axons/dendrites) of nerve cells located in ganglia.
III. contains motor neuron cell bodies.
A. I only
B. II only
C. III only
D. none of the above
15. Two neurons X and Y have excitatory input onto neuron Z. The terminal of neuron X is located 4.5 µm from the axon hillock of neuron Z, while the terminal of neuron Y is located 3.0 µm from the hillock. If, at different times, both X and Y stimulate neuron Z at the same rate and cause the same amount of post-synaptic depolarization at the terminals:
A. Neuron X will have a lesser chance of causing neuron Z to fire
B. Neuron Y will have a lesser chance of causing neuron Z to fire
C. They will both cause neuron Z to fire since action potentials are all-or-none
D. They both have an equal chance to cause neuron Z to fire.
16. In the crossed extensor reflex initiated on the right side, the motor neurons of the right biceps will:
A. not be affected
B. be stimulated by excitatory neurons
C. be inhibited by inhibitory neurons
D. be inhibited by neurons of the medulla oblongata
17. If a neuron is stimulated past threshold and the response lacks any sign of a late outward current, the neuron has probably been treated with:
A. oubain
B. TTX
C. TEA
D. pronase
18. Motor information travels down the spinal cord along the:
A. spinocerebellar tract
B. rubrospinal tract
C. fasiculus cuneatus or gracilis
D. none of the above
19. Action potentials are regenerative because:
A. they die out with distance travelled
B. there is a positive feedback loop that serves to keep it going along the axon
C. of the Na inactivation gate
D. all of the above
20. Sodium and potassium ion channel selectivity appears to be based on:
A. different charges on the ions
B. channel recognition factor
C. the fact that one is a salt
D. size and shape differences between channels
21. Masses of cell bodies and dendrites appear _____ in a fresh spinal cord or brain.
A. white
B. gray
C. brown
D. transparent
22. Absolute refractory refers to
A. an all or none action potential
B. the time after an action potential during which a neuron is less sensitive to stimulus
C. an amount of time during which the neuron is not sensitive to further stimulus
D. the fact that neurons are rapidly repolarized
23. Approximately 4 msec after a 'typical' axon is strongly depolarized:
A. all the K+ channels are closed.
B. the Na+ channels open.
C. the Na+ channels are inactivated.
D. the K+ channels are inactivated.
E. none of the above
24. During an action potential in a large axon
A. a small percentage of the total number of Na ions diffuse into the cell
B. a small percentage of the total number of K ions diffuse out of the cell
C. a large percentage of the total number of Na ions diffuse into the cell
D. a large percentage of the total number of K ions diffuse out of the cell
E. A and B only
F. C and D only
25. Which of the following is not true about an action potential in a nerve cell?
A. It is normally caused by a sudden increase in sodium-potassium pump activity.
B. It is associated with a sudden increase in sodium permeability (gates open) and a somewhat slower increase in potassium permeability (gates open).
C. It can occur in a neuron because of the unequal distribution of ions across the membrane.
D. It does not vary in amplitude with the strength of the stimulus used to trigger it.
26. Which of the following are ascending tracts in the spinal cord?
A. the cerbrospinal
B. the rubrospinal
C. the corticospinal
D. none of these
27. After an action potential, the nerve cell membrane re-develops a resting potential and
A. potassium channels in the membrane open and potassium ions diffuse outward
B. ion channels close and the membrane becomes more permeable to sodium and potassium
C. sodium channels in the membrane open and sodium ions diffuse inward
D. ion channels close and the membrane becomes less permeable to sodium and potassium
28. The withdrawel reflex involves:
A. a sensory neuron
B. an interneuron
C. a motor neuron
D. A and C only
E. all of the above
29. Neurons have different nutritional requirements than other cells in that they
A. require glucose as a source for producing ATP
B. require O2 for the breakdown of glucose
C. must aerobically respire
D. all of the above
E. none of the above
30. Ion pumps are important for which of the following?
A. long term maintenance of the resting potential
B. short term maintenance of the resting potential
C. long term maintenance of the action potential
D. short term maintenance of the action potential
31. At the neuromuscular junction which of the following is true?
A. Norepinephrine is released and is removed from the synapse by diffusion.
B. Norepinephrine is released and is removed from the synapse via reuptake.
C. Acetylcholine is released and is removed from the synapse via enzymatic breakdown.
D. Acetylcholine is released and is removed from the synapse via reuptake.
32. The effects that a neurotransmitter will have on the postsynaptic membrane is determined primarily by:
A. the chemical structure of the transmitter
B. the type of pre-synaptic cell
C. the types of enzymes located in the synapse
D. the structure of the post-synaptic receptor
33. Excitatrory post-synaptic potentials are produced when:
A. a neurotransmitter causes Na channels to open.
B. a neurotransmitter to be broken down
C. a neurotransmitter causes Na channels to close
D. a neurotransmitter causes K channels to open
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FILL-INS (@2 points):
Complete the following sentences with the most appropriate (one) word.
Choose 10 out of 12 only.
1. The difference in electrical charge between the inside and outside of a polarized nerve cell membrane is
called the _______________________ _________________________.
2. A(an) __________________ is the junction between the parts of two neurons.
3. The ____________________ root of a spinal nerve consists entirely of motor neuron axons.
4. There are approximately ________________________ pairs of spinal nerves.
5. A __________________ is a predictable, involuntary response to a stimulus.
6. Ascending motor information descends in the spinal cord in the _______________tract.
7. Proteins which allow ions to pass through membranes only after they are stimulated by chemical messengers are called ________________.
8. The nerve that passes medially and posterior to your elbow is the _________________.
9. The ionic basis for the resting and action potentials was first worked out in the __________ giant axon.
10. ______________ and _____________ were the scientists that did most of the pioneering work on APs and RPs back in the 1950s.
11. The cells that help to insulate axons in the central nervous system are ________________________.
12. Norepinephrine is removed from the synapse via _________________________________.
Essay/Short Answer (@ 10 pts). Answer only 2 of the following 3. The first 2 answered will be graded.
1) Draw and label a diagram showing a cross section through the spinal cord. Be sure to label at least two "tracts".
2) List the processes that occur durinmg synaptic transmission.
3) Draw and label a neuronal cell membrane and the inside and outside concentrations of important ions.