Question 1

Which condition contributes to the length‒tension relationship observed in skeletal muscle?

Accepted Answer

A)  When sarcomere lengths are long, thin filaments overlap. 
B)  When sarcomere lengths are long, thick and thin filaments do not overlap optimally. 
C)  When sarcomere lengths are short, thick and thin filaments do not overlap fully. 
D)  When sarcomere lengths are short, the elastic elements in the muscle are not fully stretched. 
A)  When sarcomere lengths are long, thin filaments overlap. 
B)  When sarcomere lengths are long, thick and thin filaments do not overlap optimally. 
C)  When sarcomere lengths are short, thick and thin filaments do not overlap fully. 
D)  When sarcomere lengths are short, the elastic elements in the muscle are not fully stretched. B

Question 2

Fast oxidative glycolytic fibers in skeletal muscle are used

Accepted Answer

A)  only for motions requiring maximum power output, such as jumping. 
B)  constantly, for postural activities such as standing and sitting. 
C)  intermittently, for activities requiring more force output than the fast glycolytic fibers alone can produce. 
D)  intermittently, for activities requiring more force output than the slow oxidative fibers alone can produce. 
A)  only for motions requiring maximum power output, such as jumping. 
B)  constantly, for postural activities such as standing and sitting. 
C)  intermittently, for activities requiring more force output than the fast glycolytic fibers alone can produce. 
D)  intermittently, for activities requiring more force output than the slow oxidative fibers alone can produce. D

Question 3

The force that a particular vertebrate skeletal muscle produces can be altered by a change in the

Accepted Answer

A)  size of the action potentials in motor neurons. 
B)  number of motor units recruited. 
C)  amount of calcium released in response to each action potential. 
D)  proportion of myofibrils activated per muscle fiber. 
A)  size of the action potentials in motor neurons. 
B)  number of motor units recruited. 
C)  amount of calcium released in response to each action potential. 
D)  proportion of myofibrils activated per muscle fiber. B

Question 4

What happens when Ca2+ increases in the cytoplasm of a striated muscle cell?

Accepted Answer

A)  Myosin-binding sites on actin are exposed, allowing a single cross-bridge cycle to occur. 
B)  Myosin-binding sites on actin are exposed, allowing cross-bridge cycles to occur until Ca2+ drops again. 
C)  Actin-binding sites on myosin are exposed, allowing a single cross-bridge cycle to occur. 
D)  Actin-binding sites on myosin are exposed, allowing cross-bridge cycles to occur until Ca2+ drops again. 
A)  Myosin-binding sites on actin are exposed, allowing a single cross-bridge cycle to occur. 
B)  Myosin-binding sites on actin are exposed, allowing cross-bridge cycles to occur until Ca2+ drops again. 
C)  Actin-binding sites on myosin are exposed, allowing a single cross-bridge cycle to occur. 
D)  Actin-binding sites on myosin are exposed, allowing cross-bridge cycles to occur until Ca2+ drops again.

Question 5

Refer to the figure shown.
  In the figure, which panel represents the power stroke?

Accepted Answer

A)  I 
B)  IV 
C)  V 
D)  VI 
A)  I 
B)  IV 
C)  V 
D)  VI

Question 6

Nervous signaling to smooth muscle cells

Accepted Answer

A)  is always inhibitory. 
B)  can be excitatory or inhibitory. 
C)  is all-or-nothing. 
D)  can regulate frequency, but not force, of contraction. 
A)  is always inhibitory. 
B)  can be excitatory or inhibitory. 
C)  is all-or-nothing. 
D)  can regulate frequency, but not force, of contraction.

Question 7

Cross-bridges generate force in a skeletal muscle cell any time

Accepted Answer

A)  the muscle is shortened. 
B)  there is an action potential in a motor neuron. 
C)  Ca2+ levels in the cytoplasm are high. 
D)  ATP levels are high enough. 
A)  the muscle is shortened. 
B)  there is an action potential in a motor neuron. 
C)  Ca2+ levels in the cytoplasm are high. 
D)  ATP levels are high enough.

Question 8

Explain why muscles such as rattlesnake tail-shaker muscles, which are capable of very fast activation and relaxation, tend to produce lower forces than other skeletal muscles.

Accepted Answer

Muscles that contract and relax very rap

Question 9

The elastic component of the gastrocnemius

Accepted Answer

A)  is composed of the epimysium, perimysium, and endomysium surrounding the muscle. 
B)  is composed of actin and myosin proteins within the muscle cells. 
C)  must be fully stretched before the gastrocnemius can exert any external force. 
D)  must be fully stretched in order for the muscle to exert maximum tetanic force. 
A)  is composed of the epimysium, perimysium, and endomysium surrounding the muscle. 
B)  is composed of actin and myosin proteins within the muscle cells. 
C)  must be fully stretched before the gastrocnemius can exert any external force. 
D)  must be fully stretched in order for the muscle to exert maximum tetanic force.

Question 10

During an isotonic muscle twitch, the presence of elastic elements causes the latent period to be _______ than during an isometric twitch, and the peak force transmitted through the tendon to be _______.

Accepted Answer

A)  shorter; lower 
B)  shorter; higher 
C)  longer; higher 
D)  longer; lower 
A)  shorter; lower 
B)  shorter; higher 
C)  longer; higher 
D)  longer; lower

Question 11

For contraction to occur in smooth muscle,

Accepted Answer

A)  myosin light chains must be phosphorylated. 
B)  myosin light-chain kinase must be phosphorylated. 
C)  calcium must bind to troponin C. 
D)  DHPR must interact physically with ryanodine receptor calcium channels. 
A)  myosin light chains must be phosphorylated. 
B)  myosin light-chain kinase must be phosphorylated. 
C)  calcium must bind to troponin C. 
D)  DHPR must interact physically with ryanodine receptor calcium channels.

Question 12

When the cell membrane of a vertebrate skeletal muscle is depolarized, ryanodine receptors change configuration and permit passage of Ca2+

Accepted Answer

A)  passively, from the extracellular fluid to the cytoplasm. 
B)  passively, from the sarcoplasmic reticulum to the cytoplasm. 
C)  actively, from the extracellular fluid to the cytoplasm. 
D)  actively, from the sarcoplasmic reticulum to the cytoplasm. 
A)  passively, from the extracellular fluid to the cytoplasm. 
B)  passively, from the sarcoplasmic reticulum to the cytoplasm. 
C)  actively, from the extracellular fluid to the cytoplasm. 
D)  actively, from the sarcoplasmic reticulum to the cytoplasm.

Question 13

Refer to the figure shown.
  What is the best explanation for the release of the dots at area II?

Accepted Answer

A)  DHPR actively pumping 
B)  DHPR changes conformation due to depolarization 
C)  RyR channel actively pumping 
D)  RyR changes conformation due to depolarization 
A)  DHPR actively pumping 
B)  DHPR changes conformation due to depolarization 
C)  RyR channel actively pumping 
D)  RyR changes conformation due to depolarization

Question 14

Refer to the figure shown.
  What state of muscle activity does this figure represent?

Accepted Answer

A)  Fully contracted 
B)  Somewhat contracted 
C)  Fully relaxed 
D)  Tetany 
A)  Fully contracted 
B)  Somewhat contracted 
C)  Fully relaxed 
D)  Tetany

Question 15

Briefly explain why fast glycolytic muscle fibers fatigue more rapidly than slow-twitch muscle fibers.

Accepted Answer

Fast glycolytic muscle fibers use ATP mu

Question 16

A striated muscle fiber is made up of many parallel _______, each containing a series of _______.

Accepted Answer

A)  fascicles; fibrils 
B)  myofibrils; sarcomeres 
C)  fascicles; Z discs 
D)  sarcomeres; myotomes 
A)  fascicles; fibrils 
B)  myofibrils; sarcomeres 
C)  fascicles; Z discs 
D)  sarcomeres; myotomes

Question 17

In skeletal muscle cells, cytoplasmic Ca2+ is bound by

Accepted Answer

A)  actin. 
B)  myosin. 
C)  troponin. 
D)  tropomyosin. 
A)  actin. 
B)  myosin. 
C)  troponin. 
D)  tropomyosin.

Question 18

Refer to the figure shown.
  What do the tiny dots at area I represent?

Accepted Answer

A)  Ca2+ 
B)  ATP 
C)  Phosphate 
D)  Na+ 
A)  Ca2+ 
B)  ATP 
C)  Phosphate 
D)  Na+

Question 19

In striated muscle, phosphate is released from the myosin head at the same instant that

Accepted Answer

A)  the myosin head binds to actin. 
B)  the myosin head releases from actin. 
C)  the myosin head returns to the cocked position. 
D)  the myosin head starts the power stroke. 
A)  the myosin head binds to actin. 
B)  the myosin head releases from actin. 
C)  the myosin head returns to the cocked position. 
D)  the myosin head starts the power stroke.

Question 20

Refer to the figure shown.
  What are the tiny dots at area III binding to?

Accepted Answer

A)  Ca2+ 
B)  ATP 
C)  actin 
D)  troponin 
A)  Ca2+ 
B)  ATP 
C)  actin 
D)  troponin

Exam 20: Muscle

Which condition contributes to the length‒tension relationship observed in skeletal muscle?

Fast oxidative glycolytic fibers in skeletal muscle are used

The force that a particular vertebrate skeletal muscle produces can be altered by a change in the

What happens when Ca2+ increases in the cytoplasm of a striated muscle cell?

Refer to the figure shown. In the figure, which panel represents the power stroke?

Nervous signaling to smooth muscle cells

Cross-bridges generate force in a skeletal muscle cell any time

Explain why muscles such as rattlesnake tail-shaker muscles, which are capable of very fast activation and relaxation, tend to produce lower forces than other skeletal muscles.

The elastic component of the gastrocnemius

During an isotonic muscle twitch, the presence of elastic elements causes the latent period to be _______ than during an isometric twitch, and the peak force transmitted through the tendon to be _______.

For contraction to occur in smooth muscle,

When the cell membrane of a vertebrate skeletal muscle is depolarized, ryanodine receptors change configuration and permit passage of Ca2+

Refer to the figure shown. What is the best explanation for the release of the dots at area II?

Refer to the figure shown. What state of muscle activity does this figure represent?

Briefly explain why fast glycolytic muscle fibers fatigue more rapidly than slow-twitch muscle fibers.

A striated muscle fiber is made up of many parallel _______, each containing a series of _______.

In skeletal muscle cells, cytoplasmic Ca2+ is bound by

Refer to the figure shown. What do the tiny dots at area I represent?

In striated muscle, phosphate is released from the myosin head at the same instant that

Refer to the figure shown. What are the tiny dots at area III binding to?

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

Neurons

Synapses

Sensory Processes

Nervous System Organization and Biological Clocks

Endocrine and Neuroendocrine Physiology

Reproduction

Integrating Systems at Work: Animal Navigation

Control of Movement

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

What happens when Ca²⁺ increases in the cytoplasm of a striated muscle cell?

During an isotonic muscle twitch, the presence of elastic elements causes the latent period to be _ than during an isometric twitch, and the peak force transmitted through the tendon to be _.

When the cell membrane of a vertebrate skeletal muscle is depolarized, ryanodine receptors change configuration and permit passage of Ca²⁺

A striated muscle fiber is made up of many parallel _, each containing a series of _.

In skeletal muscle cells, cytoplasmic Ca²⁺ is bound by