Question 1

In smooth muscle cells, Ca²⁺ binds to ________ which activates the enzyme ________ to phosphorylate myosin and increase force.

Accepted Answer

calmodulin

Question 2

Sketch and label a relaxed sarcomere, then draw the same sarcomere in a contracted state.The myofilaments may be represented as simple lines.

Accepted Answer

Sketch should resemb

Question 3

Define and explain the difference between isotonic, isometric and eccentric contractions and give an example of a specific movement for each.What is the role of series elastic elements in muscle contraction?

Accepted Answer

Isotonic means same tension, that is, a

Question 4

A change in smooth muscle cell tension in the absence of a change in electrical potential of the cells is described as a(n)

Accepted Answer

A)  pacemaker potential. 
B)  slow wave potential. 
C)  pharmacomechanical coupling. 
D)  electromechanical coupling. 
A)  pacemaker potential. 
B)  slow wave potential. 
C)  pharmacomechanical coupling. 
D)  electromechanical coupling.

Question 5

Which of the following is NOT a property of single-unit smooth muscles?

Accepted Answer

A)  All smooth muscle cells are connected by gap junctions. 
B)  Their contraction occurs in a coordinated manner. 
C)  Electrical responses travel directly between cells. 
D)  Only a proportion of the smooth muscle cells receive autonomic nervous input. 
E)  Each cell functions independent of its neighbor. 
A)  All smooth muscle cells are connected by gap junctions. 
B)  Their contraction occurs in a coordinated manner. 
C)  Electrical responses travel directly between cells. 
D)  Only a proportion of the smooth muscle cells receive autonomic nervous input. 
E)  Each cell functions independent of its neighbor.

Question 6

The graph below was generated by students in a physiology lab.The top trace (myogram)shows contraction force, the bottom (EMG)shows the electrical stimulus.On the graph, label a muscle twitch.What property of muscle is being tested here? What caused the increase in force (and subsequent decrease)?

Accepted Answer

The clearest single twitches are the fir

Question 7

Relative to skeletal muscle, smooth muscle

Accepted Answer

A)  only uses less energy to generate a given amount of force. 
B)  only can sustain contractile force without fatigue. 
C)  only uses calcium from the sarcoplasmic reticulum and extracellular space. 
D)  uses less energy to generate a given amount of force and can sustain contractile force without fatigue. 
E)  uses less energy to generate a given amount of force, can sustain contractile force without fatigue and uses calcium from the sarcoplasmic reticulum and extracellular space. 
A)  only uses less energy to generate a given amount of force. 
B)  only can sustain contractile force without fatigue. 
C)  only uses calcium from the sarcoplasmic reticulum and extracellular space. 
D)  uses less energy to generate a given amount of force and can sustain contractile force without fatigue. 
E)  uses less energy to generate a given amount of force, can sustain contractile force without fatigue and uses calcium from the sarcoplasmic reticulum and extracellular space.

Question 8

As a muscle cell undergoes an eccentric contraction, sarcomere length will ________ as the length of the A band ________.

Accepted Answer

increase,

Question 9

When a skeletal muscle cell contracts and the muscle shortens,

Accepted Answer

A)  myosin heads generate a single power stroke. 
B)  the position of an actin molecule relative to a myosin molecule does not change. 
C)  some myosin heads are forming crossbridges as others are releasing them. 
D)  the actin ATPase allows the actin molecule to swivel. 
E)  the actin molecule swivels during the power stroke. 
A)  myosin heads generate a single power stroke. 
B)  the position of an actin molecule relative to a myosin molecule does not change. 
C)  some myosin heads are forming crossbridges as others are releasing them. 
D)  the actin ATPase allows the actin molecule to swivel. 
E)  the actin molecule swivels during the power stroke.

Question 10

The heavy chain of myosin contains two important regions: the first acts as ________ to convert energy into movement whereas the second binds to ________.

Accepted Answer

The answer of The heavy chain of myosin contains two...

Question 11

The binding of acetylcholine to its receptor at the neuromuscular junction causes the opening of a

Accepted Answer

A)  Na⁺ channel. 
B)  channel for both Na⁺ and K⁺. 
C)  calcium channel. 
D)  ryanodine receptor. 
A)  Na⁺ channel. 
B)  channel for both Na⁺ and K⁺. 
C)  calcium channel. 
D)  ryanodine receptor.

Question 12

Describe the process of relaxation of a skeletal muscle fiber.

Accepted Answer

Relaxation is an active process, resulti

Question 13

After death, when metabolism stops, in which step of the contractile cycle must skeletal muscles remain?

Accepted Answer

A)  It depends on what part of the contractile cycle they were in at the time of death. 
B)  the power stoke phase 
C)  the rigor state 
D)  a weak binding state 
A)  It depends on what part of the contractile cycle they were in at the time of death. 
B)  the power stoke phase 
C)  the rigor state 
D)  a weak binding state

Question 14

Sketch a graph of the length-tension relationship in a contracting skeletal muscle, and explain its shape in terms of events in the sarcomere.

Accepted Answer

Sketch should resemble Figure 12.16 in t

Question 15

Define and explain the differences between slow wave potentials and pacemaker potentials in smooth muscle cells.

Accepted Answer

Slow wave potential describes the cyclic

Question 16

In comparison to skeletal muscle, smooth muscle cells function over a ________ range of muscle lengths and exhibit a speed of contraction that is ________ than skeletal muscle.

Accepted Answer

The answer of In comparison to skeletal muscle, smooth muscle...

Question 17

Match the structures with the accurate description.
-a bundle of adjacent muscle cells

Accepted Answer

A) muscle fiber 
B) fascicle 
C) sarcolemma 
D) myofibril 
E) t-tubules 
A) muscle fiber 
B) fascicle 
C) sarcolemma 
D) myofibril 
E) t-tubules

Question 18

Outline and explain the cellular event that affects the force generated by smooth muscle cells.What are the initiating events, and how do these events affect force production by the smooth muscle cell? How can this process be activated without changes in membrane potential?

Accepted Answer

See Figure 12.26 in the chapter. Describ

Question 19

Asynchronous activation of motor units is important because it functions to ________.

Accepted Answer

The answer of Asynchronous activation of motor units is important...

Question 20

Which of the following is a characteristic of slow-twitch oxidative skeletal muscle fibers?

Accepted Answer

A)  long contraction duration only 
B)  few mitochondria only 
C)  high capillary density only 
D)  long contraction duration and high capillary density 
E)  long contraction duration, few mitochondria, and high capillary density 
A)  long contraction duration only 
B)  few mitochondria only 
C)  high capillary density only 
D)  long contraction duration and high capillary density 
E)  long contraction duration, few mitochondria, and high capillary density

Exam 12: Muscles

In smooth muscle cells, Ca²⁺ binds to ________ which activates the enzyme ________ to phosphorylate myosin and increase force.

Sketch and label a relaxed sarcomere, then draw the same sarcomere in a contracted state.The myofilaments may be represented as simple lines.

Define and explain the difference between isotonic, isometric and eccentric contractions and give an example of a specific movement for each.What is the role of series elastic elements in muscle contraction?

A change in smooth muscle cell tension in the absence of a change in electrical potential of the cells is described as a(n)

Which of the following is NOT a property of single-unit smooth muscles?

The graph below was generated by students in a physiology lab.The top trace (myogram)shows contraction force, the bottom (EMG)shows the electrical stimulus.On the graph, label a muscle twitch.What property of muscle is being tested here? What caused the increase in force (and subsequent decrease)?

Relative to skeletal muscle, smooth muscle

As a muscle cell undergoes an eccentric contraction, sarcomere length will ________ as the length of the A band ________.

When a skeletal muscle cell contracts and the muscle shortens,

The heavy chain of myosin contains two important regions: the first acts as ________ to convert energy into movement whereas the second binds to ________.

The binding of acetylcholine to its receptor at the neuromuscular junction causes the opening of a

Describe the process of relaxation of a skeletal muscle fiber.

After death, when metabolism stops, in which step of the contractile cycle must skeletal muscles remain?

Sketch a graph of the length-tension relationship in a contracting skeletal muscle, and explain its shape in terms of events in the sarcomere.

Define and explain the differences between slow wave potentials and pacemaker potentials in smooth muscle cells.

In comparison to skeletal muscle, smooth muscle cells function over a ________ range of muscle lengths and exhibit a speed of contraction that is ________ than skeletal muscle.

Match the structures with the accurate description. -a bundle of adjacent muscle cells

Outline and explain the cellular event that affects the force generated by smooth muscle cells.What are the initiating events, and how do these events affect force production by the smooth muscle cell? How can this process be activated without changes in membrane potential?

Asynchronous activation of motor units is important because it functions to ________.

Which of the following is a characteristic of slow-twitch oxidative skeletal muscle fibers?

Introduction to Physiology

Molecular Interactions

Compartmentation: Cells and Tissues

Energy and Cellular Metabolism

Membrane Dynamics

Communication, Integration, and Homeostasis

Introduction to the Endocrine System

Neurons: Cellular and Network Properties

The Central Nervous System

Sensory Physiology

Efferent Division: Autonomic and Somatic Motor Control

Integrative Physiology I: Control of Body Movement

Cardiovascular Physiology

Blood Flow and the Control of Blood Pressure

Blood

Mechanics of Breathing

Gas Exchange and Transport

The Kidneys

Integrative Physiology II: Fluid and Electrolyte Balance

The Digestive System

Metabolism and Energy Balance

Endocrine Control of Growth and Metabolism

The Immune System

Integrative Physiology III: Exercise

Reproduction and Development

Filters

In smooth muscle cells, Ca²⁺ binds to which activates the enzyme to phosphorylate myosin and increase force.

As a muscle cell undergoes an eccentric contraction, sarcomere length will as the length of the A band .

The heavy chain of myosin contains two important regions: the first acts as to convert energy into movement whereas the second binds to .

In comparison to skeletal muscle, smooth muscle cells function over a range of muscle lengths and exhibit a speed of contraction that is than skeletal muscle.