A&P 1 Aranda Exam 3 (UTA) Study
Guide with Complete Solutions Latest
Updated 2024/2025
Absolute Refractory Period - Correct Answer period associated with the opening of the Na+ channels
until they begin to reset to their original resting state. (Neuron can NOT respond to another stimulus)
relative refractory period - Correct Answer follows the absolute refractory period, most Na+ channels
have returned to their resting state, some K+ channels are still open, and repolarization is occurring.
(Requires exceptionally strong stimulus to open channels)
A neuron will not respond to a second stimulus of equal strength to the first stimulus to which it has
already responded because - Correct Answer because the neuron is in the relative refractory period.
Group A fibers - Correct Answer Largest diameter, are mostly somatic and sensory fibers serving the
skin, skeletal muscles, and joints. Thicc myelin sheaths and conduct at speeds up to 150 m/s
Group B Fibers - Correct Answer Intermediate diameter, lightly myelinated fibers
Transmit at 15 m/s
Group C Fibers - Correct Answer Smallest diameter, unmyelinated ANS fibers
Transmit at 1 m/s
Excessive potassium efflux as a result of relatively slower closure of the potassium gates corresponds
to what part of an action potential curve? - Correct Answer The hyperpolarization phase of an action
potential
Which of the following could cause a graded depolarization?
A. K+ leaving the cell through leakage (nongated) channels
B. Na+ entering the cell through chemically gated channels
C. K+ leaving the cell through voltage-gated channels
, D. Na+ entering the cell through voltage-gated channels - Correct Answer B. Na+ entering the cell
through chemically gated channels
FEEDBACK: Depolarizing graded potentials are small deviations in voltage across the membrane that
make the membrane potential more negative. The diffusion of Na+ into the cell through chemically
gated channels would make the inside of the cell less negative. In other words, the influx of Na+
causes a depolarizing graded potential.
The sodium-potassium ion pump will __________. - Correct Answer pump three sodium (Na+) ions
out of the cell for every two ions of potassium (K+) it brings into the cell (3 Na+ in, 2 K+ out)
How would an increased extracellular K+ concentration affect K+ diffusion at leakage (nongated)
channels and the membrane potential? - Correct Answer A decrease in the electrochemical gradient
would reduce K+ leak so cells would be less negative (more depolarized).
FEEDBACK: Potassium ions normally diffuse out of the cell along their concentration gradient from
higher intracellular concentration to lower extracellular concentration. K+ flowing out of the cell
causes the cell to become more negative inside. If extracellular K+ is increased, the concentration
gradient across the membrane is decreased and therefore K+ is less likely to leave the cell. The
retention of positively charged ions within the cell would depolarize the membrane.
What could have resulted from an increase in extracellular K+ - Correct Answer Depolarizing graded
potential
The resting membrane potential of neurons is determined by __________. - Correct Answer the
distribution, across the cell membrane, of large anionic cytoplasmic proteins, Na+, K+, and Cl-
Which of the following describes acetylcholine? - Correct Answer Excites skeletal muscle
In a chemical synapse, which of the following best describes the role of calcium ions? - Correct
Answer Calcium ions trigger exocytosis of neurotransmitter.
Which of the following represents a hyperpolarizing change in membrane potential called an
inhibitory postsynaptic potential (IPSP)? - Correct Answer The postsynaptic membrane becomes
more permeable to potassium and chloride.
Guide with Complete Solutions Latest
Updated 2024/2025
Absolute Refractory Period - Correct Answer period associated with the opening of the Na+ channels
until they begin to reset to their original resting state. (Neuron can NOT respond to another stimulus)
relative refractory period - Correct Answer follows the absolute refractory period, most Na+ channels
have returned to their resting state, some K+ channels are still open, and repolarization is occurring.
(Requires exceptionally strong stimulus to open channels)
A neuron will not respond to a second stimulus of equal strength to the first stimulus to which it has
already responded because - Correct Answer because the neuron is in the relative refractory period.
Group A fibers - Correct Answer Largest diameter, are mostly somatic and sensory fibers serving the
skin, skeletal muscles, and joints. Thicc myelin sheaths and conduct at speeds up to 150 m/s
Group B Fibers - Correct Answer Intermediate diameter, lightly myelinated fibers
Transmit at 15 m/s
Group C Fibers - Correct Answer Smallest diameter, unmyelinated ANS fibers
Transmit at 1 m/s
Excessive potassium efflux as a result of relatively slower closure of the potassium gates corresponds
to what part of an action potential curve? - Correct Answer The hyperpolarization phase of an action
potential
Which of the following could cause a graded depolarization?
A. K+ leaving the cell through leakage (nongated) channels
B. Na+ entering the cell through chemically gated channels
C. K+ leaving the cell through voltage-gated channels
, D. Na+ entering the cell through voltage-gated channels - Correct Answer B. Na+ entering the cell
through chemically gated channels
FEEDBACK: Depolarizing graded potentials are small deviations in voltage across the membrane that
make the membrane potential more negative. The diffusion of Na+ into the cell through chemically
gated channels would make the inside of the cell less negative. In other words, the influx of Na+
causes a depolarizing graded potential.
The sodium-potassium ion pump will __________. - Correct Answer pump three sodium (Na+) ions
out of the cell for every two ions of potassium (K+) it brings into the cell (3 Na+ in, 2 K+ out)
How would an increased extracellular K+ concentration affect K+ diffusion at leakage (nongated)
channels and the membrane potential? - Correct Answer A decrease in the electrochemical gradient
would reduce K+ leak so cells would be less negative (more depolarized).
FEEDBACK: Potassium ions normally diffuse out of the cell along their concentration gradient from
higher intracellular concentration to lower extracellular concentration. K+ flowing out of the cell
causes the cell to become more negative inside. If extracellular K+ is increased, the concentration
gradient across the membrane is decreased and therefore K+ is less likely to leave the cell. The
retention of positively charged ions within the cell would depolarize the membrane.
What could have resulted from an increase in extracellular K+ - Correct Answer Depolarizing graded
potential
The resting membrane potential of neurons is determined by __________. - Correct Answer the
distribution, across the cell membrane, of large anionic cytoplasmic proteins, Na+, K+, and Cl-
Which of the following describes acetylcholine? - Correct Answer Excites skeletal muscle
In a chemical synapse, which of the following best describes the role of calcium ions? - Correct
Answer Calcium ions trigger exocytosis of neurotransmitter.
Which of the following represents a hyperpolarizing change in membrane potential called an
inhibitory postsynaptic potential (IPSP)? - Correct Answer The postsynaptic membrane becomes
more permeable to potassium and chloride.
