Question 1

Which of the following statements about a compound action potential recording is not true?

Accepted Answer

A) Each peak represents a group of axons of similar conduction velocity. 
B) Each peak represents a group of axons of similar diameter. 
C) The magnitude of each peak reflects the number of axons in that category. 
D) The magnitude of a peak is negatively correlated with axonal conduction velocity. 
E) The profiles of peaks are characteristic of and different for different peripheral nerves. 
A) Each peak represents a group of axons of similar conduction velocity. 
B) Each peak represents a group of axons of similar diameter. 
C) The magnitude of each peak reflects the number of axons in that category. 
D) The magnitude of a peak is negatively correlated with axonal conduction velocity. 
E) The profiles of peaks are characteristic of and different for different peripheral nerves. D

Question 2

Myelination increases AP conduction velocity by:

Accepted Answer

A) Increasing the axonal diameter. 
B) Increasing membrane capacitance. 
C) Limiting voltage-gated K+ channels to the nodes. 
D) Decreasing the membrane resistance. 
E) Increasing the length constant and decreasing the membrane capacitance between the nodes. 
A) Increasing the axonal diameter. 
B) Increasing membrane capacitance. 
C) Limiting voltage-gated K+ channels to the nodes. 
D) Decreasing the membrane resistance. 
E) Increasing the length constant and decreasing the membrane capacitance between the nodes. E

Question 3

Which of the following events is common to all types of sensory receptors?

Accepted Answer

A) The generation of a receptor potential. 
B) The generation of an action potential. 
C) The binding of a stimulus to a receptor. 
D) The binding of a stimulus to a membrane channel. 
E) Membrane depolarization. 
A) The generation of a receptor potential. 
B) The generation of an action potential. 
C) The binding of a stimulus to a receptor. 
D) The binding of a stimulus to a membrane channel. 
E) Membrane depolarization. A

Question 4

At the threshold for generating an action potential:

Accepted Answer

A) The membrane is at the K+ equilibrium potential. 
B) The conductances for Na+ and K+ are equal. 
C) There is a rapid opening of voltage-gated Na+ channels. 
D) K+ conductance is maximal. 
E) The transmembrane voltage is zero. 
A) The membrane is at the K+ equilibrium potential. 
B) The conductances for Na+ and K+ are equal. 
C) There is a rapid opening of voltage-gated Na+ channels. 
D) K+ conductance is maximal. 
E) The transmembrane voltage is zero.

Question 5

Which of the following stimulus parameters is not encoded in the pattern of action potentials in a sensory axon?

Accepted Answer

A) Threshold 
B) Frequency 
C) Modality 
D) Duration 
E) Intensity 
A) Threshold 
B) Frequency 
C) Modality 
D) Duration 
E) Intensity

Question 6

The axon membrane responds to an intracellular injection of a subthreshold positive current with:

Accepted Answer

A) Transient depolarization only in the region where the current is injected. 
B) Maintained depolarization until negative current is injected. 
C) Maximal depolarization locally and attenuated depolarization along the axon. 
D) Immediately opening K+ channels to maintain resting potential. 
E) Firing an action potential. 
A) Transient depolarization only in the region where the current is injected. 
B) Maintained depolarization until negative current is injected. 
C) Maximal depolarization locally and attenuated depolarization along the axon. 
D) Immediately opening K+ channels to maintain resting potential. 
E) Firing an action potential.

Question 7

The length constant of an unmyelinated axon increases as the diameter of the axon increases.This is primarily a result of:

Accepted Answer

A) Increasing membrane capacitance. 
B) Decreasing membrane capacitance. 
C) Increasing membrane resistance. 
D) Decreasing membrane resistance. 
E) Decreasing axoplasmic resistance. 
A) Increasing membrane capacitance. 
B) Decreasing membrane capacitance. 
C) Increasing membrane resistance. 
D) Decreasing membrane resistance. 
E) Decreasing axoplasmic resistance.

Question 8

The afterhyperpolarization that follows the action potential:

Accepted Answer

A) Results primarily from to the inactivation of voltage-gated Na+ channels. 
B) Makes it easier to trigger another action potential. 
C) Is the main cause of the relative refractory period. 
D) Makes it impossible to fire another action potential. 
E) Is the consequence of continuing K+ influx. 
A) Results primarily from to the inactivation of voltage-gated Na+ channels. 
B) Makes it easier to trigger another action potential. 
C) Is the main cause of the relative refractory period. 
D) Makes it impossible to fire another action potential. 
E) Is the consequence of continuing K+ influx.

Question 9

Which of the following is responsible for the repolarization of the membrane after the peak of the action potential?

Accepted Answer

A) The membrane potential reaches the Na+ equilibrium potential. 
B) The voltage-gated Na+ channels begin to inactivate. 
C) The slowly opening voltage-gated K+ channels allow K+ to enter. 
D) The influx of Na+ and the outflow of K+ are equal. 
E) There is no longer a gradient to drive K+ out of the cell. 
A) The membrane potential reaches the Na+ equilibrium potential. 
B) The voltage-gated Na+ channels begin to inactivate. 
C) The slowly opening voltage-gated K+ channels allow K+ to enter. 
D) The influx of Na+ and the outflow of K+ are equal. 
E) There is no longer a gradient to drive K+ out of the cell.

Question 10

Which of the following is not a true statement about the conduction of action potentials (APs)in axons?

Accepted Answer

A) The inward Na+ current of an AP generates an AP in the neighboring node of a myelinated axon. 
B) All APs in a given axon typically are identical in magnitude and duration. 
C) An action potential experimentally generated by a depolarization in the middle of an axon is conducted in only one direction from the site of initiation. 
D) The velocity of AP conduction is positively correlated with axon diameter. 
E) The frequency of APs is limited by the length of the refractory period. 
A) The inward Na+ current of an AP generates an AP in the neighboring node of a myelinated axon. 
B) All APs in a given axon typically are identical in magnitude and duration. 
C) An action potential experimentally generated by a depolarization in the middle of an axon is conducted in only one direction from the site of initiation. 
D) The velocity of AP conduction is positively correlated with axon diameter. 
E) The frequency of APs is limited by the length of the refractory period.

Exam 5: Generation and Conduction of Action Potentials

Which of the following statements about a compound action potential recording is not true?

Myelination increases AP conduction velocity by:

Which of the following events is common to all types of sensory receptors?

At the threshold for generating an action potential:

Which of the following stimulus parameters is not encoded in the pattern of action potentials in a sensory axon?

The axon membrane responds to an intracellular injection of a subthreshold positive current with:

The length constant of an unmyelinated axon increases as the diameter of the axon increases.This is primarily a result of:

The afterhyperpolarization that follows the action potential:

Which of the following is responsible for the repolarization of the membrane after the peak of the action potential?

Which of the following is not a true statement about the conduction of action potentials (APs)in axons?

Principles of Cell Function

Homeostasis of Body Fluids

Signal Transduction, membrane Receptors, second Messengers, and Regulation of Gene Expression

The Nervous System: Introduction to Cells and Systems

Synaptic Transmission

The Somatosensory System

The Special Senses

Organization of Motor Function

Higher Functions of the Nervous System

The Autonomic Nervous System and Its Central Control

Skeletal Muscle Physiology

Cardiac Muscle

Smooth Muscle

Overview of Circulation

Elements of Cardiac Function

Properties of the Vasculature

Regulation of the Heart and Vasculature

Integrated Control of the Cardiovascular System

Structure and Function of the Respiratory System

Static Lung and Chest Wall Mechanics

Dynamic Lung and Chest Wall Mechanics

Ventilation

Oxygen and Carbon Dioxide Transport

Control of Respiration

Non-Physiologic Functions of the Lung: Host Defense and Metabolism

Functional Anatomy and General Principles of Regulation in the Gastrointestinal Tract

The Cephalic, oral, and Esophageal Phases of the Integrated Response to a Meal

The Gastric Phase of the Integrated Response to a Meal

The Small Intestinal Phase of the Integrated Response to a Meal

The Colonic Phase of the Integrated Response to a Meal

Transport and Metabolic Functions of the Liver

Elements of Renal Function

Solute and Water Transport Along the Nephron: Tubular Function

Control of Body Fluid Osmolality and Volume

Potassium, calcium, and Phosphate Homeostasis

Role of the Kidneys in the Regulation of Acid-Base Balance

Introduction to the Endocrine System

Hormonal Regulation of Energy Metabolism

Hormonal Regulation of Calcium and Phosphate Metabolism

The Hypothalamus and Pituitary Gland

The Thyroid Gland

The Adrenal Glands

The Male and Female Reproductive Systems

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