MIDTERM EXAM Introduction to Neuroscience – Bio 3411 1999 1 ...

1
Name: _____________________________________
MIDTERM EXAM
Introduction to Neuroscience – Bio 3411
1999
1) 12 Points: Some answers are used more than once. (There are 12 correct answers; -1 for
each answer over 12.)
_____ a.
_____ b.
_____ c.
_____ d.
_____ e.
_____ f.
_____ g.
_____ h.
point furthest from E Ca
point closest to E K
the driving force on Na + is greatest.
the electrical gradient for Na + is outward.
the electrical gradient for K + is inward.
point closest to the reversal potential for Ach-activated channels.
point furthest from the reversal potential for Ca ++ channels.
the sodium current is equal and opposite to the potassium current
One Point Each Question/One Answer Only for Each Question
2) During the undershoot of the action potential:
a. All sodium channels are in the inactivated conformation.
b. The action potential threshold is unchanged from resting membrane conditions.
c. Potassium conductance is higher than at rest.
d. The sodium/potassium ATPase repolarizes the membrane.
e. The membrane potential approaches E Na

2
Midterm Exam
Introduction to Neuroscience – Bio 3411 (1999)
Name: _____________________________________
3) Which of the following is unimportant in establishing the membrane resting potential
a. The bulk concentrations of all impermeant ions.
b. The equilibrium potential for all permeable ions.
c. The intracellular concentration of potassium ion.
d. Membrane leak channels.
e. The sodium-potassium ATPase.
f. All of the above.
4) Using patch clamp technique:
a. Different channels can be distinguished according to their single channel
conductance.
b. Different channels can be distinguished according to their mean open time.
c. Different channels can be distinguished according to their inactivation properties.
d. Different channels can be distinguished according to their reversal potentials.
e. All of the above.
f. A, B & C only
5) The condition of Hyperkalemic Periodic Paralysis is a genetic disease caused by a
mutation in a voltage-gated sodium channel. However, it resembles “Hyperkalemia” a
condition where the bulk concentration of extracellular potassium is too high. Which of the
following is true:
1. The membrane resting potential in affected cells is too positive.
2. The condition could result from some sodium channels open at resting potentials.
3. A similar condition could result from a mutation that affects leak (K+ selective) channels.
4. All of the above.
5. 1 & 2 above.
6) Long QT syndrome shows a pattern of dominant inheritance because:
A. The mutant potassium channel gene suppresses the genetic expression of the cardiac sodium
channel.
B. Mutant potassium channel subunits form heteromultimers with wild-type subunits.
C. The mutant potassium channel gene shows dominant epistasis.
D. The mutant potassium channel shortens the duration of the cardiac action potential.
E. None of the above.

3
Midterm Exam
Introduction to Neuroscience – Bio 3411 (1999)
Name: _____________________________________
7) Answer: True or False: 1 pt. Each
_____ Energy is stored in a nerve cell axon and used to propagate the action potential.
_____ Both an extension cord and a nerve cell axon can conduct an electric current
“passively,” but the axon carries the passive current over a greater distances.
_____ At threshold, I NA and I K are equal and opposite, but the driving force for Na + is
greater than for K + .
_____ The length constant of a myelinated axon never exceeds the internode distance.
_____ Activation of ionotropic receptors will not result in a change of membrane
potential at the reversal potential for the channel.
_____ The speed of the action potential depends on the length constant of the axon.
_____ The lowering of total capacitance by myelin is a major energy conserving feature
of the Squid giant axon.
_____ Short term learning and memory probably involves the growth of new dendritic
circuitry
8) Fill in each blank with A, B, or C.
Synaptic Transmission: A. Ionotropic, B. Metabotropic, C. Electrical
____01._blocked by α-bungarotoxin
____02._fastest
____03._uses a second messenger system
____04._large dense core vesicles
____05._termination of action by peptidase
____06._dopamine
____07._glycine
____08._affected by Prosaic
____09._gap junctions
____10._neurotransmitter encoded by gene
____11._direct neurotransmitter binding to channel
____12._used at C-fiber presynaptic terminals in pain sensation
____13._seven transmembrane receptor protein
____14._gaba

4
Midterm Exam
Introduction to Neuroscience – Bio 3411 (1999)
Name: _____________________________________
9) Which four answers are applicable to the diagram: ____; ____; ____;____
A. facilitation
B. presynaptic facilitation
C. depression
D. spatial summation
E. temporal summation
F. long term potentiation
G. IPSPs
H. EPSP’s
I. Electrical synaptic transmission.
J. Passive potential
10) Two factors important in transferring short-term memory into long-term memory are
___________ and ___________ (fit single word answers in blanks).
11) Finish this SINGLE sentence using only the available space: The mechanism of voltagegating
of the sodium channel is essential for the propagation of the action potential because it
____________________________________________________________________. (2 pts)
12) Neurons and epidermal cells derive from which germ band of an
embryo_____________.
13) Neurons within the neural tube are born in the ventricular layer. Once born, neuronal
precusors (circle two answers):
a) migrate radially, then laterally.
b) migrate laterally, then radially.
c) do not migrate.
d) follow Bergman glia.
e) remain undifferentiated ectoderm