1
Bio 207 Exam 2 Questions with Answers (100% Correct
Answers)
What is meant by the term "resting membrane potential"? How is it
maintained? Answer: Resting membrane potential is when the
equilibrium potential of a Na+/K+ pump is between -65 and -85. (-
90mV for K+, +60mV for Na+)
It is maintained by the Na+/K+ pump but is generated by the unequal
distribution of ions.
Resting membrane potential is close to the equilibrium potential of
which ion (EK+ or ENa+)? Answer: It is much closer to the K+
equilibrium (-90mV) because the membrane is more permeable to K+
What is the role of Na+/K+ pump in maintaining membrane potential?
What is the role of fixed anions? Answer: The pumps actively bring in
K+, which passes easily through the membrane and makes the cell
interior negative
Negative anions inside the cell attract cations outside the cell
Name the six types of glial cells Answer: Schwann cells
© 2025 All rights reserved
,2
Astrocytes
Microglia
Oligodendrocyte
Ependymal
Satellite cells
What are the functions of Schwann cells in nerve conduction and nerve
regeneration following injury? Answer: Schwann cells form myelin
sheaths around peripheral axons. Myelinated axons conduct impulses
more rapidly.
When part of a PNS nerve is severed, the Schwann cell survives and
forms a regeneration tube. The tube releases chemicals that attract
growing axon and guides regrowing axon to synaptic site.
What are the functions of oligodendrocytes? Answer: They produce
myelin sheaths around axons in the CNS. One oligodendrocyte sends
extensions to several axons.
What are the functions of astrocytes? Answer: Take up K+ from the
extracellular environment to maintain ionic environment for neurons.
© 2025 All rights reserved
, 3
Take up extra neurotransmitters released from axon endings; The
chemicals are recycled. Help form the blood-brain barrier by producing
tight junctions in brain capillaries. End-feet around capillaries take up
glucose from blood for use by neurons to make ATP.
Describe ion gating in axons Answer: Changes in membrane potential
are controlled by changes in the flow of ions through ion channels.
K+ has two types of channels:
Not gated (always open); sometimes called "leaky" K+ channels
Voltage-gated K+ channels; open when a particular membrane
potential is reached
Na+ has only voltage-gated channels that are closed at rest.
The membrane is less permeable to Na+ at rest.
What happens during action potential? Answer: When membrane
potential is depolarized to -55mV, gates open that let in Na+. Na+
passes through the membrane and the membrane potential therefore
gets closer to the sodium potential. At +30mV, the sodium gates close
and the potassium ones open to release K+. Repolarization gets the
© 2025 All rights reserved
Bio 207 Exam 2 Questions with Answers (100% Correct
Answers)
What is meant by the term "resting membrane potential"? How is it
maintained? Answer: Resting membrane potential is when the
equilibrium potential of a Na+/K+ pump is between -65 and -85. (-
90mV for K+, +60mV for Na+)
It is maintained by the Na+/K+ pump but is generated by the unequal
distribution of ions.
Resting membrane potential is close to the equilibrium potential of
which ion (EK+ or ENa+)? Answer: It is much closer to the K+
equilibrium (-90mV) because the membrane is more permeable to K+
What is the role of Na+/K+ pump in maintaining membrane potential?
What is the role of fixed anions? Answer: The pumps actively bring in
K+, which passes easily through the membrane and makes the cell
interior negative
Negative anions inside the cell attract cations outside the cell
Name the six types of glial cells Answer: Schwann cells
© 2025 All rights reserved
,2
Astrocytes
Microglia
Oligodendrocyte
Ependymal
Satellite cells
What are the functions of Schwann cells in nerve conduction and nerve
regeneration following injury? Answer: Schwann cells form myelin
sheaths around peripheral axons. Myelinated axons conduct impulses
more rapidly.
When part of a PNS nerve is severed, the Schwann cell survives and
forms a regeneration tube. The tube releases chemicals that attract
growing axon and guides regrowing axon to synaptic site.
What are the functions of oligodendrocytes? Answer: They produce
myelin sheaths around axons in the CNS. One oligodendrocyte sends
extensions to several axons.
What are the functions of astrocytes? Answer: Take up K+ from the
extracellular environment to maintain ionic environment for neurons.
© 2025 All rights reserved
, 3
Take up extra neurotransmitters released from axon endings; The
chemicals are recycled. Help form the blood-brain barrier by producing
tight junctions in brain capillaries. End-feet around capillaries take up
glucose from blood for use by neurons to make ATP.
Describe ion gating in axons Answer: Changes in membrane potential
are controlled by changes in the flow of ions through ion channels.
K+ has two types of channels:
Not gated (always open); sometimes called "leaky" K+ channels
Voltage-gated K+ channels; open when a particular membrane
potential is reached
Na+ has only voltage-gated channels that are closed at rest.
The membrane is less permeable to Na+ at rest.
What happens during action potential? Answer: When membrane
potential is depolarized to -55mV, gates open that let in Na+. Na+
passes through the membrane and the membrane potential therefore
gets closer to the sodium potential. At +30mV, the sodium gates close
and the potassium ones open to release K+. Repolarization gets the
© 2025 All rights reserved
