CBN Exam II Questions And 100% Correct Answers
The resting membrane potential is closer to the equilibrium potential for _______ than the
equilibrium potential for ________. This is because ________________. - ANSWER
potassium ; sodium ; at rest the membrane has mostly potassium channels open
If you were given an ion and all you knew about this ion was that its concentration inside
the cell is higher than outside the cell, and it's a positively charged ion. Could you make
any predictions regarding the equilibrium potential of that ion? ANSWER The
equilibrium potential will be negative
Consider a neuron where the intracellular fluid contains 100 mM of potassium and the
extra-cellular fluid contains 1 mM of potassium. If cell membrane is only permeable to
potassium ions, what would be voltage across this membrane? [assume the system is at
equilibrium and at body temperature; log 100 = 2, log 10 =1; log 1 = 0; log 0.1 = -1; log
0.01 = -2]- ANSWER -124 mV
A voltage-gated sodium channel: - ANSWER has four helical transmembrane regions
that have positive charged amino acids acting as the voltage sensor
How do action potentials differ from passively conducted electrical signals such as
EPSPs? - ANSWER Action potentials are signals of fixed size and duration; passively
conducted signals are not a fixed size and duration.
What is the role of voltage-gated potassium channels in the action potential? - ANSWER
Voltage-gated potassium channels help to restore a negative membrane potential after
the peak of the action potential.
What are some similarities and differences between leak channels and voltagegated
potassium channels? - ANSWER Leak channels and voltagegated potassium channels
are both permeable to potassium ions.
, Based on the model of voltage-gated sodium channels, during the end of a depolarizing
voltage pulse prolonged to -40 mV or above, there is no current through the channel
because ________________. - ANSWER a globular part of the channel is blocking the pore.
How long does an action potential last from the start of the rising phase to the end of the
falling phase? - ANSWER 1 millisecond
Human brain is a variation of common structures found in ____ - ANSWER many
mammalian brains
Cortical tissue - ANSWER allows for higher human function like thinking and planning
describe the rat brain - ANSWER large portion of the brain is taken up by visual; most of
the corext taken up by sensory things such as seeing and hearing
Name the lobes of the human cerebrum from left to right - ANSWER Frontal lobe; Central
sulcus; parietal lobe; occipital lobe; temporal lobe (underneath)
Cerebrum - ANSWER largest part of the brain; divided into two hemispheres; divided
into different lobes
Central sulcus - ANSWER groove that divides parietal and frontal lobe
Gyrus - ANSWER bump where cortex comes out
Occipital lobe - ANSWER near cerebellum
Temporal lobe - ANSWER near ears on either side
This is what would be produced: Left cerebral hemisphere receives____ information
from the______side of the body and controls movement of the ______side of the body. -
ANSWER sensory; right; right
The resting membrane potential is closer to the equilibrium potential for _______ than the
equilibrium potential for ________. This is because ________________. - ANSWER
potassium ; sodium ; at rest the membrane has mostly potassium channels open
If you were given an ion and all you knew about this ion was that its concentration inside
the cell is higher than outside the cell, and it's a positively charged ion. Could you make
any predictions regarding the equilibrium potential of that ion? ANSWER The
equilibrium potential will be negative
Consider a neuron where the intracellular fluid contains 100 mM of potassium and the
extra-cellular fluid contains 1 mM of potassium. If cell membrane is only permeable to
potassium ions, what would be voltage across this membrane? [assume the system is at
equilibrium and at body temperature; log 100 = 2, log 10 =1; log 1 = 0; log 0.1 = -1; log
0.01 = -2]- ANSWER -124 mV
A voltage-gated sodium channel: - ANSWER has four helical transmembrane regions
that have positive charged amino acids acting as the voltage sensor
How do action potentials differ from passively conducted electrical signals such as
EPSPs? - ANSWER Action potentials are signals of fixed size and duration; passively
conducted signals are not a fixed size and duration.
What is the role of voltage-gated potassium channels in the action potential? - ANSWER
Voltage-gated potassium channels help to restore a negative membrane potential after
the peak of the action potential.
What are some similarities and differences between leak channels and voltagegated
potassium channels? - ANSWER Leak channels and voltagegated potassium channels
are both permeable to potassium ions.
, Based on the model of voltage-gated sodium channels, during the end of a depolarizing
voltage pulse prolonged to -40 mV or above, there is no current through the channel
because ________________. - ANSWER a globular part of the channel is blocking the pore.
How long does an action potential last from the start of the rising phase to the end of the
falling phase? - ANSWER 1 millisecond
Human brain is a variation of common structures found in ____ - ANSWER many
mammalian brains
Cortical tissue - ANSWER allows for higher human function like thinking and planning
describe the rat brain - ANSWER large portion of the brain is taken up by visual; most of
the corext taken up by sensory things such as seeing and hearing
Name the lobes of the human cerebrum from left to right - ANSWER Frontal lobe; Central
sulcus; parietal lobe; occipital lobe; temporal lobe (underneath)
Cerebrum - ANSWER largest part of the brain; divided into two hemispheres; divided
into different lobes
Central sulcus - ANSWER groove that divides parietal and frontal lobe
Gyrus - ANSWER bump where cortex comes out
Occipital lobe - ANSWER near cerebellum
Temporal lobe - ANSWER near ears on either side
This is what would be produced: Left cerebral hemisphere receives____ information
from the______side of the body and controls movement of the ______side of the body. -
ANSWER sensory; right; right
