Interactive Lecture Quiz

1
Interactive Lecture Quiz 4 on Chapter 8
Neurophysiology

• Spring, 2008
• By Patricia L. Mansfield, Ph.D.
• Directions. Take this quiz using your powerpoint
  viewer to test yourself and to get immediate
  feedback on your answer choice.
• I obtained some animations or videos from
  internet classes or from your textbook author to
  demonstrate the important principles covered in
  this quiz.

2
Lets review some of the facts you learned when
you studied the Transmembrane Potential and add
a few facts to this knowledge base.

• The selective permeability of the cell membrane
  controls the concentration of positive and
  negative ions in the ICF and ECF.
• Some sodium ions diffuse into the cell through
  leaky channels some potassium diffuses out of
  the cell through channels that are always open.
• The sodium-potassium pump maintains a balance
  between the ICF and ECF concentrations of sodium
  and potassium such that
• SodiumICF lt SodiumECF and PotassiumICF
  gt PotassiumECF.
• This membrane system pumps 3 sodium ions out of
  the cell for every 2 potassium ions pumped into
  the cell.
• Anions trapped inside cells explain the negative
  value of the resting membrane potential.
• The resting membrane potential is most
  sensitive to changes in the potassium ion
  concentration outside the cell.
• In excitable cells, the membrane potential
  shifts away from the resting value depending
  upon the level of stimulation of the cell.
• One very important mechanism for this change is
  that closed, gated channels open under certain
  conditions when a signal molecule is present
  and more ions move into the cell.

3
Apply the facts in the first slide to neurons.

• Potassium channels are both gated and ungated in
  neurons.
• Sodium channels are always gated and rarely
  leaky.
• Gated channels open only when the cell is
  stimulated.
• -70mV is a normal resting membrane potential for
  many CNS neurons. However, this value can vary
  from 60mV to 90mV depending upon the
  characteristics of the particular neuron being
  studied.

3
4
1. Children who could not move their muscles
could feelpain. Which part of the nervous system
has been damaged?a. afferent axons b. efferent
axons c. brain d. sympathetic

• Afferent axons
• Conduct an action potential when a receptor acts
  as a transducer
• Carry sensory information into the CNS
• Efferent axons
• Conduct an action potential when a signal
  molecule is released from another CNS neuron
• Carry motor information to an effector, for
  example skeletal muscle

Identify the afferent and efferent sides of this
reflex arc http//ext.sac.edu/faculty_staff/mansf
ield_patricia/Animations/reflex_arc.html
5
2. Sodium ions enter a neuron during an action
potential. Which type of feedback is demonstrated
in this response?a. negative b.positive c.
neither

• Physical Factors behind the Action Potential
• http//psych.hanover.edu/krantz/neural/actionpoten
  tial.html
• Uncovering misconceptions about the resting
  membrane potential by Dee Silverthorn, 2002
• http//advan.physiology.org/cgi/content/full/26/2/
  69

6
3. Most synapses are classified as _____.a.
electrical b. chemical c. multimodal
d. continuous
6
7
Synapse Mechanism Signal (Neurotransmitter)
Receptor Binding
Figure 8-20 Events at the synapse
8
4. Saltatory conduction occurs in _____.a.
astrocytes b. microglia c. myelinated
axons d. unmyelinated axons
9
5. What is (directly) responsible for the ion
movement that creates an action potential?a.
voltage-gated ion channels b. chemically-gated
ion channelsc. ungated channels d.
mechanically-gated ion channels

• This CNS multipolar neuron has chemically-regulate
  d gates on its dendrites and cell body--1, 3,
  and 4.The voltage-regulated gates on the axon
  hillock are indicated by 2. This is the area
  responsible for generating the action potential.

10
6. How does an action potential (AP) differ from
an EPSP (excitatory postsynaptic potential)?a.
During an AP, the membrane potential becomes more
positive.b. During an AP, sodium ions move into
the cell.c. An AP is an all-or-none event.d. An
AP is an electrical signal.
11
Silverthorn, Figure 8-7 Graded potentials
decrease in strength as they spread out from the
point of origin
12
Silverthorn, Figure 8-9 The action potential
13
Silverthorn, Figure 8-10 Model of the
voltage-gated channel Na
14
6. How does an action potential (AP) differ from
an EPSP (excitatory postsynaptic potential)?a.
During an AP, the membrane potential becomes more
positive.b. During an AP, sodium ions move into
the cell.c. An AP is an all-or-none event.d. An
AP is an electrical signal.

• Neuron 1 has a resting membrane potential of
  -70mV and a threshold of -50mV.
• A threshold stimulus is a stimulus that moves the
  membrane potential _____ .
• If I apply a stimulus that moves the membrane
  potential 40mV, I will get an ____ as soon as
  the membrane potential reaches ____ .
• If I apply a stimulus that moves the membrane
  potential 10mV, I will get an ____ , but no ____

15
7. Which of the following is a gas? a. CCKl b.
aspartate c. nitric oxide d. serotonin

• Review the list of the major neurotranmitters of
  the NS in your syllabus
• Know the key facts concerning their biosynthetic
  pathways, mechanism for degradation, and
  pharmacology

16
8. Which ion will hyperpolarize the membrane when
it moves into a neuron?a. Na b. K c.
Cl- d. GABA
17
Neurocrines
Table 8-4-2 Major Neurocrines
18
9. When can a greater than normal stimulus
(suprathreshold stimulus) trigger an AP?a.
during the absolute refractory periodb. when the
neuron is at restc. during the relative
refractory period d. a and c e. b and c

• Neuron 1 has a resting membrane potential of
  -70mV and a threshold of -50mV.
• A threshold stimulus is a stimulus that moves the
  membrane potential _____ .
• If I apply a stimulus that moves the membrane
  potential 40mV, I will get an ____ as soon as
  the membrane potential reaches ____ .
• If I apply a stimulus that moves the membrane
  potential 10mV, I will get an ____ , but no ____
  .

19
10. Which of the following is an inhibitory
neurotransmitter?a. aspartate b. glutamate
c. ACh d. GABA
20
11. What event will the application of an
inhibitory neurotransmitter trigger?a. AP
b. EPSP c. IPSP d. influx of Na ions

• Neuron 2 has a resting membrane potential of
  -70mV, a threshold of -50mV and a membrane
  potential of -80mV after a hyperpolarizing
  stimulus was delivered.
• If I apply a threshold stimulus under these
  conditions, I will get an _____ , but no ____
  because the positive change of ____ caused by the
  threshold stimulus is not sufficient to bring the
  membrane potential to -50mV.
• I need a stimulus sufficient to produce a ____
  change in the membrane potential to get an action
  potential.

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Answers

• 1. B
• 2. B
• 3. B
• 4. C
• 5. A
• 6. C
• 7. C
• 8. C
• 9. E
• 10. D
• 11. C