Upgrade to remove ads
Only $35.99/year

BIOL 3320 Exam 3

Terms in this set (80)

Do you think testosterone directly act
upon the central nervous system to
masculinize it?
No
Why aren't female mammals masculinized?
Perinatal estradiol (E2) level is very low,
Alpha-fetoprotein in the blood plasma prevents circulating E2 from reaching the estrogen receptors in female brains.
If you inject aromatase inhibitor to a
male rat perinatally, the brain of the rat
in adulthood will be
Feminized
Stimulation of birth canal during parturition in sheep
results in oxytocin release in the brain. Accordingly,
cesarean section performed on a sheep results in a
mother without any oxytocin. Does this sheep show
maternal behavior?
No
Which of the following effects of hormone
is activational?
Injection of testosterone in a male rat
castrated in adulthood elicits male-typical
reproductive behavior
If you treat newly hatched female
songbirds with estradiol, the brain of
the bird will be
Masculinized
The masculinization effect of estradiol in the
previous question is called
Organizational effect
Elevated levels of testosterone in male songbirds activate
singing behavior. If you castrate a male bird in adulthood,
will the bird sing normal songs?
No
Castrating a male songbird in the summer
_________ and injection of testosterone into
the castrated males ___________.
Abolishes singing, reinstate
singing
Castrating a male garter snake _________
and injection of testosterone into the
castrated
males ___________.
None of the above.
Stimulate courtship behavior,
abolish courtship behavior
Abolish courthip behavior, reinstate
courtship behavior
In whiptail lizards, injection of progesterone agonist,
R5020 results in __________, whereas
administration of progesterone antagonist, RU486
results in ___________.
Male behavior, lack of
male behavior
Central infusion of AVP into male prairie voles
facilitate pair-bond formation, but the same
treatment applied to male montane voles
does not. What differs between the two
species?
The AVP receptors differ in
distribution
What is the cellular mechanisms underlying
species-specific distribution of AVP receptors
in the CNS?
Regulatory region of AVP
receptor genes
What does perinatal exposure to
environmental estrogen do to the brain of
female mammals?
Masculinize
If you inject aromatase inhibitor to a male rat
perinatally, the brain of the rat in adulthood will be
_______. This effect of hormone is called
________.
Feminized, organizational
True or false: Garter snakes, whiptail lizards,
and naked mole rats are all example of
testosterone not playing a role in activating
male-specific mating behavior.
True
Central infusion of arginine vasopressin (AVP)
facilitated pair-bond formation in male prairie
(monogamous) males but not in male montane
(promiscuous) voles. Based on these results, the
researchers hypothesized that
The difference in the
species reside in the
receptor expressions
What happens to the amplitude of action potential
when you inject progressively larger current into a
neuron?
The amplitude of the action
potential does not change
Does action potential travel in both direction along
the axon?
No, Because of refractory period, a patch of membrane that fired action potential cannot be reactivated again.
Locations of a neuron where synaptic inputs
are received are called _______, and the
location where action potentials are
generated is called _______.
Dendrites, axon hillock
You are obtaining intracellular recordings from a
pair of neurons. Depolarizing neuron 1 resulted in
depolarization of the the neuron 2. This led you to
suspect that neurons 1 and 2 are synaptically
connected. When you hyperpolarize the neuron 1,
the neuron 2 also hyperpolarized. The synapses
between the two neurons are
Electrical
One of the passive membrane properties that
affect the synaptic integration of neuron is time
constant. There are two neurons with the same
threshold and input resistance, but neuron 1 has a
shorter time constant than neuron 2. When you
inject a suprathreshold step current of the same
amplitude to these neurons, which one spikes
first?
Neuron 1
Action potential generated by the axon hillock
propagates towards the axon terminals, but
do not return back in retrograde direction.
The reason for the unidirectional propagation
of action potential is
Refractory period
For a given neuron, the equilibrium potential
of Na+ is +60mV and the resting membrane
potential is -100mV. What happens to Na+
ions when all the Na+ channels of the cell
membrane open?
Na+ flows into the cell
For a given neuron, the equilibrium potential of
Na+ is +60mV and the resting membrane potential
is -100mV. When all the Na+ channels of the cell
membrane open and Na+ flow into the cell, what
happens to the membrane potential of the neuron?
Depolarizes
For a given neuron, the equilibrium potential
of K+ is -100mV and the resting membrane
potential is also -100mV. What happens
when all the K+ channels of the cell
membrane open?
There is no net movement
of K+
The resting membrane potential of most neurons
are between -40 and -80mV. Equilibrium potential
of Ca+ is about +140mV. When Ca+ channels of a
neuron opens, the membrane potential will be
Depolarized
Membrane potential of a neuron typically reaches +20mV
during action potential, but not much more. Why do we
not see more depolarized membrane potential (such as
+100mV) at the peak of an action potential?
Because equilibrium potential of Na+ is around +20mV
When membrane potential of a neuron is
depolarized, Na+ current flows into the neuron
quickly, but after reaching a peak, the Na+ current
amplitude decreases over the next few
milliseconds. Which of the molecular events
explain the decrease in the current?
Inactivation of voltage-
gated Na+ channels
After a neuron spike an action potential, there
is a period of time during which an excitability
of neuron is either abolished or reduced
(refractory period). Which of the molecular
events explain the refractory period of a
neuron?
Inactivation of
voltage-gated Na+
channels
The graph below shows the K+ currents of a
neuron mediated by voltage-gated K+
channels when the neuron is depolarized to
+20mV at time zero. Does the channel
inactivate?
No
If the voltage-gated K+ channels do not inactivate.
How does the channels close at the end of the
action potential?
Because the membrane potential repolarizes as K+ flows out of
the neuron
Two ways to increase the conduction velocity
of action potentials along axons are to
________, and to ___________.
Increase the axon diameter,
myelinate axons
The resting membrane potential of a neuron can
be calculated using Goldman-Hodgkin-Katz
equation. Based on the equation, the resting
membrane potential
Depends on permeability of ions
Depends on intracellular and
extracellular concentration of ions
True or false: For a given neuron, the equilibrium
potential of Na+ is +20mV and the resting
membrane potential is -100mV. When this neuron
was repetitively stimulated, the neuron spiked a
train of action potentials. The peak of the action
potentials recorded was +40mV. (Assume that
Ca2+ does not contribute to the generation of
action potential in this neuron).
False
After opening, voltage-gated Na+ channels
inactivate. Which of the following behavior of
neurons can be explained by the inactivation of
voltage-gated Na+ channels ?
Repolarization of the membrane
potential during action potential
Refractory period
There are a variety of ion channels expressed by
neurons with different gating mechanisms. Name
the type of channels that account for the resting
membrane potentials, action potentials, and post-
synaptic potentials.
Non-gated open channels, voltage-
gated channels, ligand-gated channels
What determines whether a postsynaptic
neuron exhibit IPSP or EPSP?
The type of receptors
expressed by the
postsynaptic neuron
You are recording the membrane potential of a
postsynaptic neuron with a resting membrane
potential of -60mV. The equilibrium potential of
Na+ is +20mV. When ligand-gated Na+ channels
of the post-synaptic membrane open, Na+ ions
_______ the cell, and the membrane potential
_________. This is called _______.
Flow into, depolarizes, EPSP
You are recording the membrane potential of a
post-synaptic neuron with a resting membrane
potential of -60mV. The equlibirum potential of Cl-
is -80mV. When ligand-gated Cl- channels of the
postsynaptic membrane open, Cl- ions _______
the cell, and the membrane potential _________.
This is called _______.
Flow into, hyperpolarizes, IPSP
Scientists discovered that the type of voltage-gated Ca2+
channels (VGCC) found in the presynaptic terminals of the frog
neuromuscular junction is the N-type channel. You are doing an
experiment to record the frog muscle tension in response to
motor nerve stimulation
in vitro. When you apply antagonist for
N-type VGCC to this preparation and stimulate the motor nerve,
you will observe
No tension develops in
response to motor nerve
stimulation
Are all sensory receptor cells neurons?
No
1. For a given chemical synapse, the presynaptic
neuron releases GABA and the postsynaptic
neuron expresses GABA A receptors, ionotropic
receptors that pass Cl- when open. The resting
membrane potential of the postsynaptic neuron is -
70mV and the equilibrium potential of Cl- is -80mV.
When the presynaptic neuron fires action potential,
the postsynaptic neuron show
IPSP
2. For the previous question, what happens
to the postsynaptic neuron when you elicit an
action potential from the presynaptic neuron
in the presence antagonist for voltage-gated
Ca2+ channels?
There will be no
postsynaptic potential.
3. You are recording the membrane potential of a
postsynaptic neuron innervated
by two presynaptic neurons
A and B. When you stimulate presynaptic neuron A, you
recorded EPSP from the postsynaptic neuron. When you
stimulate both A and B simultaneously, however, there was
no postsynaptic potenti
al recorded. This is because neuron B
makes _______ synaptic connection with the postsynaptic
neuron. This phenomenon is called __________.
Inhibitory, spatial summation
How are external stimuli converted into
changes in membrane potential by the
receptor cells?
External stimuli activate the
receptor proteins that
change the ionic
conductances across the
membrane
The figure below shows receptive fields of
somatosensory neurons in humans. Which of
the following statements is correct?
Small receptive fields
permit high spatial
resolution
How are the quality of signals (i.e., color or pitch of
sound) encoded by the receptor cells?
1) Population coding
2) Labeled-line coding
Why is ATPase activity enhanced when
the Ca2+ concentration is increased?
Because ATPase activity of myosin
depends on the binding of myosin to actin,
which is facilitated by the high levels of
Ca2+
In the figure below, why is there no
tension in the presence of ATP and in
the absence of Ca2+?
Because myosin cannot bind to actin
Why is the tension maintained in the absence of
ATP and Ca2+?
Because myosin cannot be
dissociated from actin
Sensory receptor cells express sensory
receptor molecules that convert cellular
events to neuronal signal. This process is
called
Sensory transduction
True or false? Threshold detection refers to
the stimulus amplitude that elicits action
potential from the sensory receptor cells.
False
True or false? In a sensory system that uses
population coding such as in the olfactory
system, each receptor cell responds to
multiple qualities of the sense.
True
When you observe sarcomeres during
muscle contraction, ______ and ______
shorten but _____ remains the same.
I band, H zone, A band
Rigor mortis is a condition in which skeletal
muscles temporarily remain in a rigid state of
contraction due to the absence of ATP, occurs
a few hours after death. Which of the
following steps is blocked by the absence of
ATP?
Detachment of myosin
from actin
What are the similarities and differences of postsynaptic
neurons and sensory receptor cells?
see notes
In response to an action potential generated by a muscle fiber,
Ca2+ binds to troponin that facilitates muscle contraction. However
, intracellular concentration of Ca2+ of muscle fibers at the resting state is very low. Where does Ca2+ come from in response to action
potential?
Intracellular store
Calcium pumps in on the sarcoplasmic reticulum (SR) actively
transport Ca2+ into SR from the myoplasm against the concentration
gradient. Ca2+ concentration gradient inside of SR and myoplasm
are determined by
The concentration of free
Ca2+ inside and outside
of SR.
In excitation-contraction coupling:
The muscle action potential
propagates down the
transverse tubule
True or false: Dihydropyridine receptors
expressed by the T-tubule are voltage-gated
Ca2+ channels. Extracellular Ca2+ that enters
through the channels in response to action
potential initiates muscle contraction.
False
We studied two examples of fast twitch
muscles. Fish sonic mucles and insect
flight muscles can generate fast twitch
by ________ and by ________,
respectively.
Having a short Ca2+ transients in
myoplasm, decoupling Ca2+ transients
with force generation
When a plug is placed in your right ear
and a sound is broadcasted from the
coordinate (0,0), you will report that the
sound originates from
Your left
Does a space-specific neuron in ICX respond to a
tone of sound delivered only to one ear?
No, ICX neurons only respond when sound
is delivered to both ears.
Which of the following combination of
ITD and ILD correspond to a sound
originating from the coordinate (0, 0)?
ITD = 0msec, ILD = 0 dB
Which of the following combination of
ITD and ILD correspond to a sound
originating from the coordinate (30R,+30)?
ITD = +60 usec (right leading left), ILD = +10dB
(right louder than left)
A sound was perceived by an owl, and
its ITD was -60 usec (left leading right),
and ILD was -10dB (left louder than
right). From which quadrant did the
sound originate?
Lower left
Neurons A through E shown below are
coincidence detectors. When a sound entered
the auditory neural network below, neuron A
responded to the sound the most. The sound
must have
Originated from the left of the subject
Which of the following combination of ITD
and ILD correspond to a sound originating
from the coordinate (30L, -30)?
ITD = -60usec (leftleading right), ILD =-10dB (left louder than right)
True or false? Each space-specific
neuron in the external nucleus of the
inferior colliculus (ICX) of an owl
responds to a combination of an ITD
and ILD that corresponds to a unique
address in space.
True
Which of the following statements
about ITD encoding is correct?
ITD is coded by a delay line and a coincidence detector neuron
Time codes are converted into space code by space-specific neurons
Which of the following statements is
correct?
A.
When a pair of prism is placed on a
young (<200 days old) owl, the ITD
responsiveness of the space-
specific
neurons become shifted after 6 weeks.
B.
When a pair of prism is placed on a
young (<200 days old) owl,
new axonal
projections grow from ICC to ICX.
C.
When a pair of prism is placed on a
older owl (>200 days old), they also
grow new axonal projections from ICC
to ICX.
D.
A and B
E.
A, B, and C
A and B
Mechanosensory
neurons from which
region of the body activate medial giant
interneuron (MGI) in crayfish?
Head
Which of the following statements
about the activation of LGI is correct?

A.
It receives sensory information
from the head region and project
it to the tail region
B.
It receives sensory information
from the head region and project
it to the tail region
C.
It receives sensory information
from the tail region and project it
to the head region
D.
It receives sensory information
from the tail region and project it
to the anterior abdomen
D
Giant interneurons and motoneurons
refer to
neurons with axons with a large diameter. Why
are escape response mediated by giant
interneurons and giant
motoneurons
with large
diameter axons?
Speed
The wiring diagram below shows the LGI circuit. When
mechanosensory
neurons are stimulated, the LGI
showed EPSPs shown below. Which one of the input to
the LGI neuron contribute to alpha and beta?
.
Both a and b contribute to
β and c contributes to α
How does the time constant affect
temporal summation?
Longer time constant
makes it easier to
summate
True or false: For a given postsynaptic neuron, the equilibrium potential of Cl- is
-100mV and the resting membrane potential is -80mV. When the neuron presynaptic to
the neuron in question was repetitively stimulated, GABA A receptors expressed by the
postsynaptic neurons were activated. GABA A receptors are ionotropic receptors that
pass Cl- when open. The peak amplitude of the inhibitory postsynaptic potential (IPSP)
reached -110mV due to temporal summation.
False. Cl- equilibrium potential is -100mV, so even with temporal summation, IPSP does
not become more hyperpolarized than -100mV
For a given neuron, the equilibrium potential of Ca2+ is +40mV and the resting
membrane potential is -100mV. In response to synaptic stimulation, voltage-gated Ca2+
channels expressed by the neuron opened. In this case, what happens to the Ca2+ and the
membrane potential of the neuron?
Ca2+ flows into the cell, and depolarize the membrane potential.
Nicotinic acetylcholine receptor is an ionotropic receptor that opens in response to
acetylcholine, and passes a combination of K+ and Na+ currents. A postsynaptic neuron
has a resting membrane potential of -70mV and the Na+ equilibrium potential of 0mV.
This postsynaptic neuron expresses nicotinic acetylcholine receptors. When the neuron
presynaptic to the postsynaptic neurons was stimulated (and release acetylcholine into
synaptic cleft), _______________ (species of ion) _______________ (net movement of
ion) and ______________ the membrane potential. This change in membrane potential
is called ___________.
a. Na+, flows out of, depolarize, IPSP
b. K+, flows out of, hyperpolarize, IPSP
c. Na+, flows into, depolarize, EPSP
d. K+, flows into, depolarize, EPSP
e. Na+, flows into, depolarize, EPSP
E
Other sets by this creator