Question 1

Explain in mechanistic terms why the action potential can travel a great distance along an axon without degrading.

Accepted Answer

The same mechanism that is responsible f

Question 2

Compared to neural signaling, endocrine signaling is

Accepted Answer

A)  faster and broadcast more discretely. 
B)  faster and broadcast more widely. 
C)  slower and broadcast more widely. 
D)  slower and broadcast more discretely. 
A)  faster and broadcast more discretely. 
B)  faster and broadcast more widely. 
C)  slower and broadcast more widely. 
D)  slower and broadcast more discretely.

Question 3

The absolute refractory period of the action potential is best explained by

Accepted Answer

A)  inactivated voltage-gated sodium channels. 
B)  closed voltage-gated sodium channels. 
C)  open slow calcium channels. 
D)  inactivated voltage-gated potassium channels. 
A)  inactivated voltage-gated sodium channels. 
B)  closed voltage-gated sodium channels. 
C)  open slow calcium channels. 
D)  inactivated voltage-gated potassium channels.

Question 4

Refer to the figure shown.
  How would the trace on the right look if the neuron was soaking in tetraethylammonium (TEA)?

Accepted Answer

A)  The inward ionic current would disappear. 
B)  The outward ionic current would disappear. 
C)  The trace would look exactly like the trace in the left panel. 
D)  The outward ionic current would be amplified. 
A)  The inward ionic current would disappear. 
B)  The outward ionic current would disappear. 
C)  The trace would look exactly like the trace in the left panel. 
D)  The outward ionic current would be amplified.

Question 5

Suppose there is a small patch of membrane from a mammalian muscle fiber, with a small volume of adjacent cytoplasm and extracellular fluid. Assume that the membrane is most permeable to K+. There are 110,000 cations and 110,000 anions in each fluid compartment. In the center of the cell

Accepted Answer

A)  there would be a slight negative charge. 
B)  there would be a strong negative charge. 
C)  the overall charge neutrality would be maintained independently of the membrane potential. 
D)  there would be a slight positive charge. 
A)  there would be a slight negative charge. 
B)  there would be a strong negative charge. 
C)  the overall charge neutrality would be maintained independently of the membrane potential. 
D)  there would be a slight positive charge.

Question 6

According to the Nernst equation, which change will depolarize Vm, the membrane potential?

Accepted Answer

A)  A decrease in temperature 
B)  An increase in the valence of the ion species involved 
C)  A decrease in the concentration of anions inside the membrane 
D)  A decrease in the electromotive force of the ion 
A)  A decrease in temperature 
B)  An increase in the valence of the ion species involved 
C)  A decrease in the concentration of anions inside the membrane 
D)  A decrease in the electromotive force of the ion

Question 7

The separation of positive and negative charges constitutes

Accepted Answer

A)  resistance. 
B)  an electric current. 
C)  a voltage. 
D)  capacitance. 
A)  resistance. 
B)  an electric current. 
C)  a voltage. 
D)  capacitance.

Question 8

Refer to the figure shown.
  How many separate current pulses cause the membrane potential to reach the threshold?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  5 
A)  1 
B)  2 
C)  3 
D)  5

Question 9

Suppose there is a small patch of membrane from a mammalian muscle fiber, with a small volume of adjacent cytoplasm and extracellular fluid. Assume that the membrane is most permeable to K+. There are 110,000 cations and 110,000 anions in each fluid compartment. The membrane potential results from

Accepted Answer

A)  only six pairs of ions sitting on the membrane. 
B)  the thousands of ions sitting on the membrane. 
C)  the overall difference intra- and extra cellular ion concentrations in the volume of cell. 
D)  movement of ions across the cell membrane. 
A)  only six pairs of ions sitting on the membrane. 
B)  the thousands of ions sitting on the membrane. 
C)  the overall difference intra- and extra cellular ion concentrations in the volume of cell. 
D)  movement of ions across the cell membrane.

Question 10

For a hormone to elicit a specific response from a cell, the cell must possess

Accepted Answer

A)  a synapse. 
B)  a cell body. 
C)  dendrites specific to the hormone. 
D)  receptor proteins specific to the hormone. 
A)  a synapse. 
B)  a cell body. 
C)  dendrites specific to the hormone. 
D)  receptor proteins specific to the hormone.

Question 11

_______ prevents bidirectional propagation of action potentials.

Accepted Answer

A)  The inactivation of Na+ channels 
B)  A decrease in membrane resistance 
C)  Myelination 
D)  The K+ channel 
A)  The inactivation of Na+ channels 
B)  A decrease in membrane resistance 
C)  Myelination 
D)  The K+ channel

Question 12

Refer to the figure shown.
  Which statement offers the best explanation for the difference between the middle panel and the lower panel?

Accepted Answer

A)  The membrane in the lower panel is producing a lower current. 
B)  There is a lower resistance in the lower panel at the point where voltage is measured. 
C)  There is a greater capacitance in the lower panel at the point where voltage is measured. 
D)  The membrane voltage measured in the lower panel is farther away from the current pulse. 
A)  The membrane in the lower panel is producing a lower current. 
B)  There is a lower resistance in the lower panel at the point where voltage is measured. 
C)  There is a greater capacitance in the lower panel at the point where voltage is measured. 
D)  The membrane voltage measured in the lower panel is farther away from the current pulse.

Question 13

Refer to the figure shown.
  In the figure, the _______ decreases with distance.

Accepted Answer

A)  graded potential 
B)  action potential 
C)  membrane current 
D)  membrane capacitance 
A)  graded potential 
B)  action potential 
C)  membrane current 
D)  membrane capacitance

Question 14

Which structure is most responsible for the all-or-none property of the action potential?

Accepted Answer

A)  Myelin 
B)  Voltage-gated K+ channels 
C)  Voltage-gated Na+ channels 
D)  Leakage of K+ channels 
A)  Myelin 
B)  Voltage-gated K+ channels 
C)  Voltage-gated Na+ channels 
D)  Leakage of K+ channels

Question 15

Refer to the figure shown.
  Which technique was used to collect the data shown in the figure?

Accepted Answer

A)  Patch-clamp 
B)  Hodgkin clamp 
C)  Current-clamp 
D)  Voltage-clamp 
A)  Patch-clamp 
B)  Hodgkin clamp 
C)  Current-clamp 
D)  Voltage-clamp

Question 16

Which statement regarding the structure of the voltage-gated Na+ channels is false?

Accepted Answer

A)  P loops mediate ion selectivity. 
B)  It has four domains with extensive sequence homology. 
C)  The channel protein changes its primary structure in response to membrane depolarization. 
D)  A cytoplasmic loop is thought to inactivate the channel by blocking the opening. 
A)  P loops mediate ion selectivity. 
B)  It has four domains with extensive sequence homology. 
C)  The channel protein changes its primary structure in response to membrane depolarization. 
D)  A cytoplasmic loop is thought to inactivate the channel by blocking the opening.

Question 17

Refer to the figure shown.
  Why do the channels at II on the figure stay open longer than those at I?

Accepted Answer

A)  Channels at I are responding to a depolarization, whereas channels at II are responding to a hyperpolarization. 
B)  The depolarization is a faster event compared to the repolarization. 
C)  Channels at I are less sensitive to voltage compared to channels at II. 
D)  Channels at I become inactivated, whereas channels at II close due to membrane voltage. 
A)  Channels at I are responding to a depolarization, whereas channels at II are responding to a hyperpolarization. 
B)  The depolarization is a faster event compared to the repolarization. 
C)  Channels at I are less sensitive to voltage compared to channels at II. 
D)  Channels at I become inactivated, whereas channels at II close due to membrane voltage.

Question 18

Which statement about the startle response of the cockroach is true?

Accepted Answer

A)  Vibrations of hairs generate nerve impulses in sensory neurons. 
B)  Sound waves or air currents synapse with the filiform hairs. 
C)  Sensory neurons synapse with and excite the dorsal hollow spinal cord. 
D)  At the metathoracic ganglion, the interneurons synaptically inhibit leg motor neurons. 
A)  Vibrations of hairs generate nerve impulses in sensory neurons. 
B)  Sound waves or air currents synapse with the filiform hairs. 
C)  Sensory neurons synapse with and excite the dorsal hollow spinal cord. 
D)  At the metathoracic ganglion, the interneurons synaptically inhibit leg motor neurons.

Question 19

Compare and contrast the techniques of patch clamping and voltage clamping.

Accepted Answer

Both patch clamping and voltage clamping

Exam 12: Neurons

Explain in mechanistic terms why the action potential can travel a great distance along an axon without degrading.

Compared to neural signaling, endocrine signaling is

The absolute refractory period of the action potential is best explained by

Refer to the figure shown. How would the trace on the right look if the neuron was soaking in tetraethylammonium (TEA)?

Suppose there is a small patch of membrane from a mammalian muscle fiber, with a small volume of adjacent cytoplasm and extracellular fluid. Assume that the membrane is most permeable to K+. There are 110,000 cations and 110,000 anions in each fluid compartment. In the center of the cell

According to the Nernst equation, which change will depolarize Vm, the membrane potential?

The separation of positive and negative charges constitutes

Refer to the figure shown. How many separate current pulses cause the membrane potential to reach the threshold?

Suppose there is a small patch of membrane from a mammalian muscle fiber, with a small volume of adjacent cytoplasm and extracellular fluid. Assume that the membrane is most permeable to K+. There are 110,000 cations and 110,000 anions in each fluid compartment. The membrane potential results from

For a hormone to elicit a specific response from a cell, the cell must possess

_______ prevents bidirectional propagation of action potentials.

Refer to the figure shown. Which statement offers the best explanation for the difference between the middle panel and the lower panel?

Refer to the figure shown. In the figure, the _______ decreases with distance.

Which structure is most responsible for the all-or-none property of the action potential?

Refer to the figure shown. Which technique was used to collect the data shown in the figure?

Which statement regarding the structure of the voltage-gated Na+ channels is false?

Refer to the figure shown. Why do the channels at II on the figure stay open longer than those at I?

Which statement about the startle response of the cockroach is true?

Compare and contrast the techniques of patch clamping and voltage clamping.

Animals and Environments: Function on the Ecological Stage

Molecules and Cells in Animal Physiology

Genomics, Proteomics, and Related Approaches to Physiology

Physiological Development and Epigenetics

Transport of Solutes and Water

Nutrition, Feeding, and Digestion

Energy Metabolism

Aerobic and Anaerobic Forms of Metabolism

The Energetics of Aerobic Activity

Thermal Relations

Food, Energy, and Temperature at Work: The Lives of Mammals in Frigid Places

Synapses

Sensory Processes

Nervous System Organization and Biological Clocks

Endocrine and Neuroendocrine Physiology

Reproduction

Integrating Systems at Work: Animal Navigation

Control of Movement

Muscle

Movement and Muscle at Work: Plasticity in Response to Use and Disuse

Introduction to Oxygen and Carbon Dioxide in Physiology

External Respiration: the Physiology of Breathing

Transport of Oxygen and Carbon Dioxide in Body Fluids With an Introduction to Acid- Base Physiology

Circulation

Oxygen, Carbon Dioxide, and Internal Transport at Work: Diving by Marine Mammals

Water and Salt Physiology: Introduction and Mechanisms

Kidneys and Excretion With Notes on Nitrogen Excretion

Water, Salts, and Excretion at Work: Mammals of Deserts and Dry Savannas

Water and Salt Physiology of Animals in Their Environments

Filters

Suppose there is a small patch of membrane from a mammalian muscle fiber, with a small volume of adjacent cytoplasm and extracellular fluid. Assume that the membrane is most permeable to K⁺. There are 110,000 cations and 110,000 anions in each fluid compartment. In the center of the cell

According to the Nernst equation, which change will depolarize V_m, the membrane potential?

Which statement regarding the structure of the voltage-gated Na⁺ channels is false?