Question 1

Acetylcholinesterase removes ACh from receptors.

Accepted Answer

A) True 
 B)False

Question 2

Energy sources available to form ATP in muscle fibers in the absence of oxygen include

Accepted Answer

A)  creatine phosphate 
B)  chemiosmosis 
C)  glycolysis 
D)  creatine phosphate and glycolysis 
E)  chemiosmosis and glycolysis 
A)  creatine phosphate 
B)  chemiosmosis 
C)  glycolysis 
D)  creatine phosphate and glycolysis 
E)  chemiosmosis and glycolysis

Question 3

More tension is developed during twitch summation than during a single twitch because the duration of elevated cytosolic Ca2+ concentration increases during summation, thus increasing the availability of cross-bridge binding sites.

Accepted Answer

A) True 
 B)False

Question 4

Muscle tension

Accepted Answer

A)  is created during muscle contraction as the tension generated by the contractile elements is transmitted via the connective tissue and tendons to the bones 
B)  is the force exerted on a muscle by the weight of an object 
C)  is greater than the load during an isometric contraction 
D)  all of these 
E)  none of these 
A)  is created during muscle contraction as the tension generated by the contractile elements is transmitted via the connective tissue and tendons to the bones 
B)  is the force exerted on a muscle by the weight of an object 
C)  is greater than the load during an isometric contraction 
D)  all of these 
E)  none of these

Question 5

During coactivation

Accepted Answer

A)  All of the muscle fibers in a skeletal muscle are activated simultaneously. 
B)  The gamma motor-neuron and alpha motor-neuron systems to a skeletal muscle are activated simultaneously. 
C)  All of the cross bridges within a single skeletal muscle are activated simultaneously. 
D)  The primary (annulospiral) and secondary (flower-spray) endings within a muscle spindle are activated simultaneously. 
E)  None of these. 
A)  All of the muscle fibers in a skeletal muscle are activated simultaneously. 
B)  The gamma motor-neuron and alpha motor-neuron systems to a skeletal muscle are activated simultaneously. 
C)  All of the cross bridges within a single skeletal muscle are activated simultaneously. 
D)  The primary (annulospiral) and secondary (flower-spray) endings within a muscle spindle are activated simultaneously. 
E)  None of these.

Question 6

The shorter a muscle fiber is before the onset of a contraction, the greater the force that can be developed upon the subsequent contraction because the thin filaments are already partially slid inward.

Accepted Answer

A) True 
 B)False

Question 7

Single-unit smooth muscle

Accepted Answer

A)  contains an abundance of gap junctions and forms functional syncytia 
B)  is self-excitable 
C)  is found in the walls of the digestive, reproductive, and urinary tracts and small blood vessels 
D)  all of these 
E)  contains an abundance of gap junctions and forms functional syncytia and is self-excitable 
A)  contains an abundance of gap junctions and forms functional syncytia 
B)  is self-excitable 
C)  is found in the walls of the digestive, reproductive, and urinary tracts and small blood vessels 
D)  all of these 
E)  contains an abundance of gap junctions and forms functional syncytia and is self-excitable

Question 8

The corticospinal system controls fine, discrete, voluntary body movements.

Accepted Answer

A) True 
 B)False

Question 9

Complete each of the following statments.
____________________ ions function as the intracellular signal for contraction.

Accepted Answer

The answer of Complete each of the following statments.
____________________ ions...

Question 10

Cross bridges

Accepted Answer

A)  bind to actin during muscle contraction 
B)  consist of tropomyosin heads 
C)  are globular heads made of myosin 
D)  do not bend during muscle contraction 
E)  bind to actin during muscle contraction and are globular heads made of myosin 
A)  bind to actin during muscle contraction 
B)  consist of tropomyosin heads 
C)  are globular heads made of myosin 
D)  do not bend during muscle contraction 
E)  bind to actin during muscle contraction and are globular heads made of myosin

Question 11

Cross bridges have actin binding sites that are normally covered by troponin and tropomyosin except during excitation-contraction coupling.

Accepted Answer

A) True 
 B)False

Question 12

The I band of the sarcomere is characterized by

Accepted Answer

A)  overlapping thin and thick filaments 
B)  only the presence of thick filaments 
C)  the presence of thin filaments and actin 
D)  a dark coloration 
E)  the presence of thin filaments, actin, and a dark coloration 
A)  overlapping thin and thick filaments 
B)  only the presence of thick filaments 
C)  the presence of thin filaments and actin 
D)  a dark coloration 
E)  the presence of thin filaments, actin, and a dark coloration

Question 13

The origin of a muscle is its

Accepted Answer

A)  main, thickest part 
B)  middle, thinner part 
C)  movable end of attachment 
D)  source of development in the fetus 
E)  stationary end of attachment 
A)  main, thickest part 
B)  middle, thinner part 
C)  movable end of attachment 
D)  source of development in the fetus 
E)  stationary end of attachment

Question 14

Complete each of the following statments.
The only energy source that can be used directly by the contractile machinery of a muscle fiber is ____________________.

Accepted Answer

The answer of Complete each of the following statments.
The only...

Question 15

Twitch summation

Accepted Answer

A)  results from increases in cytosolic calcium levels 
B)  pumping of calcium into the sarcoplasmic reticulum 
C)  can be enhanced by allowing a cell to completely relax 
D)  rarely results in tetany 
E)  none of these 
A)  results from increases in cytosolic calcium levels 
B)  pumping of calcium into the sarcoplasmic reticulum 
C)  can be enhanced by allowing a cell to completely relax 
D)  rarely results in tetany 
E)  none of these

Question 16

____ is not required for contraction of smooth muscle fibers.

Accepted Answer

A)  Calcium 
B)  Calmodulin 
C)  Phosphate 
D)  ATP 
E)  Troponin 
A)  Calcium 
B)  Calmodulin 
C)  Phosphate 
D)  ATP 
E)  Troponin

Question 17

Complete each of the following statments.
____________________ proteins function as calcium-release channels in the muscle cell.

Accepted Answer

The answer of Complete each of the following statments.
____________________ proteins...

Question 18

Muscle fibers develop tension by

Accepted Answer

A)  contraction of sarcomeres 
B)  shortening 
C)  the pushing of myosin by actin 
D)  contraction of sarcomeres and shortening 
E)  none of these 
A)  contraction of sarcomeres 
B)  shortening 
C)  the pushing of myosin by actin 
D)  contraction of sarcomeres and shortening 
E)  none of these

Question 19

Twitch summation

Accepted Answer

A)  is a means by which gradation of muscle contraction may be accomplished 
B)  results from the additional release of Ca2+ within the cytosol of muscle fibers 
C)  results from increasing the frequency at which motor units are firing within a muscle 
D)  is a means by which gradation of muscle contraction may be accomplished and results from increasing the frequency at which motor units are firing within a muscle 
E)  all of these 
A)  is a means by which gradation of muscle contraction may be accomplished 
B)  results from the additional release of Ca2+ within the cytosol of muscle fibers 
C)  results from increasing the frequency at which motor units are firing within a muscle 
D)  is a means by which gradation of muscle contraction may be accomplished and results from increasing the frequency at which motor units are firing within a muscle 
E)  all of these

Question 20

Foot proteins

Accepted Answer

A)  span the gap between a lateral sac of the sarcoplasmic reticulum and the adjacent T tubule 
B)  are believed to serve as Ca2+ channels 
C)  bind to and pull the thin filaments inward toward the A band's center during muscle contraction 
D)  span the gap between a lateral sac of the sarcoplasmic reticulum and the adjacent T tubule, and are believed to serve as Ca2+ channels 
E)  none of these 
A)  span the gap between a lateral sac of the sarcoplasmic reticulum and the adjacent T tubule 
B)  are believed to serve as Ca2+ channels 
C)  bind to and pull the thin filaments inward toward the A band's center during muscle contraction 
D)  span the gap between a lateral sac of the sarcoplasmic reticulum and the adjacent T tubule, and are believed to serve as Ca2+ channels 
E)  none of these

Exam 8: A--Muscle Physiology

Acetylcholinesterase removes ACh from receptors.

Energy sources available to form ATP in muscle fibers in the absence of oxygen include

More tension is developed during twitch summation than during a single twitch because the duration of elevated cytosolic Ca2+ concentration increases during summation, thus increasing the availability of cross-bridge binding sites.

Muscle tension

During coactivation

The shorter a muscle fiber is before the onset of a contraction, the greater the force that can be developed upon the subsequent contraction because the thin filaments are already partially slid inward.

Single-unit smooth muscle

The corticospinal system controls fine, discrete, voluntary body movements.

Complete each of the following statments. ____________________ ions function as the intracellular signal for contraction.

Cross bridges

Cross bridges have actin binding sites that are normally covered by troponin and tropomyosin except during excitation-contraction coupling.

The I band of the sarcomere is characterized by

The origin of a muscle is its

Complete each of the following statments. The only energy source that can be used directly by the contractile machinery of a muscle fiber is ____________________.

Twitch summation

____ is not required for contraction of smooth muscle fibers.

Complete each of the following statments. ____________________ proteins function as calcium-release channels in the muscle cell.

Muscle fibers develop tension by

Twitch summation

Foot proteins

Introduction to Physiology and Homeostasis

Cell Physiology

The Plasma Membrane and Membrane Potential

Principles of Neural and Hormonal Communication

A--The Central Nervous System

B--The Central Nervous System

A--The Peripheral Nervous System: Afferent Division; Special Senses

B--The Peripheral Nervous System: Afferent Division; Special Senses

The Peripheral Nervous System: Efferent Division

B--Muscle Physiology

A--Cardiac Physiology

B--Cardiac Physiology

The Blood Vessels and Blood Pressure

The Blood

Body Defenses

A--The Respiratory System

B--The Respiratory System

A--The Urinary System

B--The Urinary System

A--Fluid and Acid-Base Balance

B--Fluid and Acid-Base Balance

A--The Digestive System

B--The Digestive System

Energy Balance and Temperature Regulation

A--Principles of Endocrinology: the Central Endocrine Glands

B--Principles of Endocrinology: the Central Endocrine Glands

A--The Peripheral Endocrine Glands

B--The Peripheral Endocrine Glands

A--The Reproductive System

B--The Reproductive System

Filters

More tension is developed during twitch summation than during a single twitch because the duration of elevated cytosolic Ca²⁺ concentration increases during summation, thus increasing the availability of cross-bridge binding sites.