Download P531: Exam 1 Sample Question Set #2 A few words of advice (again

P531: Exam 1 Sample Question Set #2
A few words of advice (again):
A) Only attempt to answer these questions when you feel confident with the material. In other
words, use them as a assessment of your readiness. Don’t have the answers nearby.
B) Don’t use these questions as an estimate of what will be on the exam... anything from lecture
can be on the exam even if a question doesn’t appear on practice sets.
C) Give yourself a time limit. All of your exams (including the state-wide final exam) will average
about 1 minute per question. Use these practice questions to prepare for that pace.
D) Answer questions as we’ve discussed them in lecture.
E) Answer the question as it is written... period. Don’t add words and don’t ignore words.
1. The absolute refractory period after an action potential can be explained by
a. delayed opening of voltage-gated Cl- channels.
b. slow closing of voltage-gated K+ channels.
c. physical inactivation of voltage-gated Na+ channels.
d. a bias toward the equilibrium potential for K+.
e. Two of the above are correct.
2. The signal intensity of a single graded potential
a. will not change as it moves across the membrane.
b. is always lower than the action potential threshold.
c. is an all-or-none characteristic.
d. is always depolarizing.
e. Two of the above are correct.
3. If the membrane potential changes from -71 mV to -70 mV
a. it is being depolarized.
b. some potassium ion channels may have opened.
c. it has moved away from its membrane threshold.
d. summation of graded potentials must have occurred.
e. Two of the above are correct.
4. If a very intense excitatory stimulus occurs very close to the axon hillock
a. a larger than normal action potential will be fired.
b. multiple action potentials will be generated.
c. the relative refractory period will be interrupted.
d. action potentials will summate.
e. Two of the above are correct.
5. The relative refractory period of an action potential:
a. is a time when the neuron cannot be stimulated to fire an action potential.
b. comes before the absolute refractory period.
c. occurs when many Na+ channels are closed but ready and able to open.
d. last a little more than one second.
e. None of the above are correct.
6. The sum of the electrochemical diffusion for all ions at normal permeability levels is
a. the point at which a neuron is most depolarized.
b. also known as the resting membrane potential.
c. biased toward the equilibrium potential for sodium.
d. a theoretical point that doesn’t exist in normal neurons.
e. Two of the above are correct.
7. The concentration of sodium is greater in the extracellular fluid compared to the intracellular fluid.
If the membrane potential was equal to the equilibrium potential for sodium, the net direction of
the electrochemical driving force acting on sodium would
a. be inward.
b. be outward.
c. hyperpolarize the cell.
d. be neutral.
e. Two of the above are correct.
8. As a motor neuron increases its rate of activation the force generated by the motor unit will
increase because
a. the length of muscle fibers increases due to actin and myosin cross-bridging.
b. there is an incomplete relaxation of the sarcomere between action potentials.
c. the faster action potentials from the motor neuron activate more muscle fibers.
d. more ATP is released to allow more efficient myosin activity.
e. Ca2+ re-uptake is actively blocked to allow an increase in cross-bridging.
9. Comtan® is a catechol-O-methyl transferase (COMT) inhibitor. If prescribed to a patient with
Parkinson's disease you should expect to see
a. an increase in dopamine production.
b. a decreased rate of dopamine reuptake.
c. an increase in presynaptic dopamine levels.
d. a decrease in synaptic transmission.
e. Two of the above are correct.
10. When compared to the normal aging process, amyotrophic lateral sclerosis leads to a more rapid
loss motor neurons that innervate skeletal muscle fibers. Which of the following would you
expect to see in a patient with ALS?
a. An increase in the force production of remaining motor units.
b. An increase in maximum force production.
c. A decrease the innervation ratio of remaining motor units.
d. No change in the amount of divergence by motor neurons.
e. Two of the above are correct.
11. Which of the following will lead to the slowest depolarization of a neuron after neurotransmittter
release?
a. an ionotropic Na+ channel
b. a metabotropic Cl- channel
c. an ionotropic K+ channel
d. a metabotropic Ca2+ channel
e. an ionotropic Ca2+ channel
12. As an action potential is transmitted throughout a muscle fiber, the initial increase in sarcomeric
calcium concentration is the result of the
a. direct activation of voltage-gated calcium channels in the t-tubule.
b. indirect activation of voltage-gated Ca2+ channels in the t-tubule by DHP receptors.
c. interaction between DHP receptors and Ca2+ channels in the sarcoplasmic reticulum.
d. calcium-mediated calcium release from the sarcoplasmic reticulum.
e. actions of primary active transport of Ca2+ into the sarcoplasm.
13. When a person is performing a voluntary task that relies on the effective production of muscular
force, the biomechanics of that person's movement will often put the limbs to be used in a
position that leads to the
a. availability of space within the sarcomere for further shortening.
b. longest initial length of the sarcomeres within a muscle fiber.
c. greatest number of available sites for myosin-actin cross-bridging.
d. preferential use of eccentric contractions.
e. Two of the above are correct.
14. The mechanism of neurotransmitter removal in the neuromuscular junction is
a. enzymatic degradation.
b. secondary active transport into the presynaptic terminal.
c. diffusion out of the synaptic cleft.
d. facilitated diffusion into the post-synaptic terminal.
e. removal by glial cells.
15. Which of the following is always the same between skeletal and smooth muscle contraction?
a. An action potential initiates the contraction.
b. Contraction is calcium-dependent.
c. Actin-myosin separation is directly related to ATP attachment.
d. Troponin binds calcium to regulate actin binding sites
e. Two of the above are correct.
16. Succinylcholine is an acetylcholine agonist that resists enzymatic degradation. Due to its effect
on neuromuscular junction transmission, it makes sense for it to be used
a. as a muscle relaxant.
b. as a remedy for curare (ACh receptor antagonist) poisoning.
c. to enhance the control of muscle contraction in myasthenia gravis cases.
d. on people who have been exposed to organophosphates like sarin gas.
e. to decrease acetylcholine production.
17. An isometric contraction occurs when the muscle is being activated but no movement is
occurring. This kind of contraction is used to stabilize a joint. How would you characterize the
force produced by an isometric contraction?
a. Greater than a concentric contraction, but weaker than an eccentric contraction.
b. Weaker than either eccentric or concentric contractions.
c. Stronger than either eccentric or concentric contractions.
d. Stronger than a concentric contraction but equal to an eccentric contraction.
e. It's not possible to predict isometric force output.
18. Patients that rely on Botox (botulinum toxin) injections for cosmetic reduction of wrinkles must
continually pay for more injections to reduce the same wrinkles because eventually
a. the damaged post-synaptic receptors will be replaced.
b. neurotransmitter production will return to normal levels.
c. the concentration of toxin will decrease below a functional level.
d. vesicles will be able to dock with the presynaptic terminal.
e. new molecules of acetylcholinesterase will be made.
19. Malignant hyperthermia resulting from an allergic reaction to an anesthetic leads to violent
muscular contraction, increased body temperature and respiratory failure as a result of
a. massive acetylcholine release.
b. a sharp increase in extracellular [Ca2+].
c. excessive ryanodine receptor activation.
d. hyperexcitation due to cerebral seizure.
e. depolarizing inhibition.
20. Which of the following treatments would work best to alleviate symptoms of depression?
a. Block the receptors that bind GABA or glycine.
b. Inhibit the reuptake of serotonin from the synapse.
c. Prescription of a dopamine antagonist.
d. Engage the parasympathetic system with a cholinergic agonist.
e. None of the above would be effective.
21. When the phosphate leaves the myosin head
a. the myosin head pivots.
b. a cross-bridge is formed.
c. ATP is bound by myosin.
d. the myosin-actin bond is broken.
e. None of the above are correct.
22. ___________________ is NOT a specialization that enhances the communication between a motor
neuron and a muscle fiber.
a. The quantity of acetylcholine released
b. The number of ACh receptors
c. The use of SNAREs to release ACh
d. The amount of surface area in the synapse
e. Two of the above are correct answers.
23. Smooth muscle differs from skeletal muscle in the role played by
a. actin.
b. myosin.
c. tropomyosin.
d. troponin.
e. Two of the above are correct.
24. In a smooth muscle, ____________ will always lead to contraction.
a. increased MLC phosphatase activity
b. Ca2+ binding to troponin
c. ACh release from a neuron
d. calmodulin activation
e. Two of the above are correct.
25. Depolarizing inhibition could result from
a. the opening of ligand-gated potassium channels.
b. the persistent presence of too much neurotransmitter.
c. a voltage-gated sodium channel blocker.
d. an acetylcholinesterase blocker.
e. Two of the above are correct.